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|An American woodcock at Magee Marsh Wildlife Area, Oak Harbor, Ohio. Photo courtesy of Allan Clayborn.|
The American woodcock is native to the forested portions of eastern North America [70,167]. Breeding range of the American woodcock extends from Nova Scotia west to southern Manitoba and south through the eastern and central United States to northern Florida and eastern Texas. Breeding American woodcocks occur at low densities throughout the species' range [140,167] but are most abundant north of 40 °N latitude . Breeding bird densities are highest in Canada and states immediately adjacent to the Canadian border [46,107,167]. The American woodcock's winter range overlaps extensively with the southern portion of its breeding range, which extends from Maryland west to southern Missouri and south through the Atlantic coastal states to northern Florida and eastern Texas [38,46,70,107,107]. The winter distribution of the American woodcock is widespread, with highest densities occurring in 3 areas: eastern Texas to central Louisiana; the coastal plain of South Carolina; and the lower Delmarva Peninsula to eastern Virginia [26,107,159,167]. The American woodcock is casual or transient in parts of the western United States and Mexico [38,62]. Severity of winter weather, earthworm (Lumbriculida) distribution, availability of suitable forest habitats, and length of the growing season may dictate the geographic distribution of the American woodcock [70,167]. NatureServe provides a distributional map of the American woodcock.
Throughout its range, the American woodcock requires a mixture of openings, shrublands, and forests in uplands and lowlands in close proximity to one another. American woodcocks occur in diverse types of openings such as early-successional old fields reverting to forest, agricultural fields, pastures, wetlands, and clearcuts [70,152]. Shrublands include dense tickets of alder (Alnus spp.), willow (Salix spp.), and dogwood (Cornus spp.) . Forests include hardwood, mixed hardwood-conifer, and conifer forests in various stages of succession. In the North, American woodcocks typically occur in early to mid-successional 2nd- or 3rd-growth forests dominated by aspen (Populus spp.), birch (Betula spp.), oak (Quercus spp.), hickory (Carya spp.), and maple (Acer spp.). They also inhabit conifer forest dominated by spruce (Picea spp.), balsam fir (Abies balsamea), and pine (Pinus spp.) [38,62,70,125]. In the South, American woodcocks typically occur in mid- to late-successional bottomland hardwood forests, such as baldcypress-tupelo (Taxodium distichum-Nyssa spp.) swamps or elm-ash (Ulmus-Fraxinus spp.)-cottonwood forests. Loblolly pine (P. taeda), shortleaf pine (P. echinata), and longleaf pine (P. palustris) forests and mixed pine-hardwood forests also provide habitat for American woodcocks in the South [40,141].
Canadian Maritime Provinces: In Nova Scotia and New Brunswick, American woodcocks occurred in spruce-balsam fir, jack pine (P. banksiana), spruce-tamarack (Larix laricina), and spruce-jack pine forests and in bogs dominated by leatherleaf (Chamaedaphne calyculata), bog Labrador tea (Ledum groenlandicum), bog laurel (K. polifolia), and rhodora (Rhododendron canadense) [57,133,134]. In Terrebonne County, Quebec, American woodcocks occurred in pastures, wet meadows, upland forests dominated by yellow birch (Betula alleghaniensis), sugar maple (Acer saccharum), red maple (A. rubrum), American beech (Fagus grandifolia), eastern hemlock (Tsuga canadensis), and balsam fir, and in lowland areas dominated by alder and willow [179,180].
Maine: Many studies of American woodcock were conducted at the Moosehorn National Wildlife Refuge in northeastern Maine [32,35,95,96,104,106,107,132,147,148,149,150,153,168]. The refuge is located in "primary woodcock breeding range"  and has been managed for American woodcocks since the 1930s . Openings used by American woodcocks at the refuge included old fields, cultivated blueberry (Vaccinium spp.) fields, pastures, hayfields, and clearcuts. Forests included 2nd-growth stands of conifers (e.g., white (Picea glauca), red (P. rubens), and black spruce (P. mariana), balsam fir, eastern white (Pinus strobus) and red (P. resinosa) pine, and tamarack), hardwoods (e.g., paper birch (Betula papyrifera), gray birch (B. populifolia), red maple, quaking aspen (Populus tremuloides), and bigtooth aspen (Populus grandidentata)), and mixed hardwood-conifer stands. On moist sites and in some old fields, American woodcocks occurred in pure and mixed stands of speckled alder (Alnus rugosa) [35,96,107,132,148,149,151,153]. Mendall and Alduous  conducted a study at the Moosehorn National Wildlife Refuge and nearby areas in Maine and the Canadian Maritime Provinces. Five habitats were identified as being important to American woodcocks in this region: young (approximately 15-30 years old and under 25 feet (7.6 m) tall), 2nd-growth hardwood forest with gray birch, paper birch, quaking aspen, bigtooth aspen, red maple, alder, and willow; conifer forest dominated by either spruce (red, white, and/or black spruce) and balsam fir (in northern and eastern Maine) or eastern white and/or red pine and eastern hemlock (in central and southern Maine); mixed hardwood-conifer forest; shrubland characterized as "extremely thick growths of young hardwood trees or shrubs"; and openings such as agricultural fields and old fields. The authors reported that American beech-yellow birch and American beech-yellow birch-sugar maple habitats, "although very common throughout New England are seldom utilized by American woodcocks regardless of the age or density of the stand" . However, researchers reported American woodcocks in and on the edge of these forests in other parts of the species' range [30,54].
In Penobscot County, American woodcocks primarily used 2nd-growth hardwood forest dominated by gray birch, red maple, American elm (Ulmus americana), white ash (Fraxinus americana), and quaking aspen, and various types of openings, particularly old fields, pastures, and Christmas tree plantations [30,119]. Old fields (approximately 20-30 years since cultivation) were dominated by grasses (Poaceae) and hawkweed (Hieracium spp.) [84,85]. American woodcocks also occurred in speckled alder habitat with other, scattered hardwoods; mixed red maple-conifer forest; mixed-conifer forest with tamarack; eastern white pine forest; red pine forest; and a northern whitecedar (Thuja occidentalis) lowland [30,119,171]. Alder was the dominant understory shrub in all American woodcock habitats in this area [30,119].
New Hampshire: American woodcocks occurred in pitch pine/bear oak-dwarf chinkapin oak (Pinus rigida/Quercus ilicifolia-Q. prinoides) barrens of New Hampshire . American woodcocks were associated with edge habitats in sugar maple-yellow birch-American beech forest on the White Mountains National Forest .
Massachusetts: In 4 counties in central Massachusetts, American woodcocks occurred in alder thickets; red maple-aspen-birch forests; red pine and eastern white pine plantations; and blueberry and old fields [101,155]. Black locust (Robinia pseudoacacia) was the dominant woody species in diurnal habitats on Martha's Vineyard, and black highbush blueberry (Vaccinium atrococcum) was dominant on Nantucket Island .
New York: In the Happy Valley Wildlife Management Area in Oswego County, American woodcocks occurred in 2nd- and 3rd-growth hardwood, mixed hardwood-conifer and conifer forests, and old fields. Common hardwood trees included red maple, sugar maple, black cherry (Prunus serotina), American beech, ash, and aspen. Common conifers included Norway spruce (Picea abies), eastern hemlock, eastern white pine, and red pine. Old fields were dominated by grasses, sedges (Carex spp.), and/or mosses with scattered trees and shrubs, particularly spirea (Spiraea spp.). Shrub habitats included speckled alder, abandoned apple (Malus domestica) orchards, arrowwood (Viburnum dentatum) thickets, and dogwood thickets .
Michigan: In the upper peninsula, American woodcocks occurred in hardwood and mixed hardwood-conifer forests dominated by aspen, red maple, and paper birch; conifer forests dominated by balsam fir, black spruce, and tamarack; moist alder lowlands; and bog birch (Betula pumila)-leatherleaf-bog rosemary (Andromeda glaucophylla) bogs [3,29]. At Houghton Lake State Forest in the north-central lower peninsula [126,129], American woodcocks occurred in dense, young (<10-year-old, seedling-sized (<1 inch (2.54-cm) DBH) aspen forests, intermediate-aged (10- to 20-year-old, sapling-sized (1-5 inch (2.54-12.7 cm) DBH) aspen forests, mixed-hardwood forest dominated by pole-sized (5-9 inch (12.7-22.9 cm) DBH) aspen, oak, and maple, and pure alder forests . On High Island in northeastern Lake Michigan, American woodcocks occurred in old fields with staghorn sumac (Rhus typhina), pin cherry (Prunus pensylvanica), aspen, beaked hazelnut (Corylus cornuta), red-osier dogwood (Cornus sericea), willow, apple, paper birch, and sugar maple, and 2nd-growth hardwood forests and conifer forests with sugar maple, paper birch, aspen, red maple, and balsam fir . According to Beckwith , American woodcocks were absent from annual and biennial agricultural fields in Michigan but present in old fields in various stages of succession, including those dominated by perennial grasses, mixed perennial forbs and grasses, shrubs, and trees.
Wisconsin: In north-central Wisconsin, American woodcocks occurred in poorly drained northern hardwood forest dominated by red maple and well-drained northern hardwood forest dominated by sugar maple. American woodcocks also occurred in moist, lowland spruce-balsam fir and spruce-tamarack forests . Several studies in Sawyer, Price, and Lincoln counties in northern Wisconsin found American woodcocks were most common in young (<10 years old) aspen forest, followed by alder and northern hardwood forest, but were rare in conifer forest [45,46,53]. In Portage County, American woodcocks occurred in upland shrub, hardwood, conifer, hardwood-conifer, and alder forests. Dominant hardwoods in American woodcock habitats included quaking aspen, paper birch, red maple, northern red oak (Quercus rubra), and white oak (Q. alba) .
Minnesota: In Mille Lacs Wildlife Management Area in east-central Minnesota, American woodcocks occurred in upland hardwood forest dominated by aspen, red maple, and paper birch, upland conifer forest dominated by balsam fir and black spruce, and moist lowland areas dominated by alder, willow, and/or bur oak (Quercus macrocarpa) . In Carlton County, American woodcocks used upland hardwood and hardwood-conifer forests dominated by quaking and bigtooth aspen, paper birch, red maple, northern red oak, basswood (Tilia americana), sugar maple, and American elm; upland 2nd-growth (20- to 30-year old) red-white-jack pine forest; upland shrublands dominated by beaked hazelnut; lowland black spruce-balsam fir forest; northern whitecedar-yellow birch forest; lowland shrublands dominated by highbush cranberry (Viburnum trilobum), red-osier dogwood, and/or mountain maple (Acer spicatum); and riparian balsam poplar (Populus balsamifera) associations [110,173]. Old fields, particularly those adjacent to aspen forest, were frequently used .
Pennsylvania: Throughout Pennsylvania, American woodcocks occurred at sites dominated by alder (56%), apple (42%), hawthorn (Crataegus spp., 19%), silky dogwood (Cornus amomum, 19%), blackberry (Rubus spp., 19%), and/or willow (14%). Regional differences in the composition of various American woodcock habitats occurred, with alder more prevalent in American woodcock habitats in the central and northeastern regions and aspen more prevalent in the northwestern region, but overall, alder "stands out as the most important cover type" in Pennsylvania . In Huntingdon and Centre counties, American woodcocks occurred in pitch pine/bear oak-dwarf chinkapin oak barrens, aspen, scrub oak, alder (e.g., speckled and hazel alder (Alnus serrulata)), hawthorn-apple, mixed oak, gray dogwood (Cornus racemosa), and conifer forests, as well as old fields, agricultural fields, and pastures [49,51,63,71,72,93,97,108,116,158]. In Mercer and Lawrence counties, American woodcocks occurred in scrub-shrub palustrine wetlands and upland aspen stands. American woodcocks most commonly occurred in upland quaking aspen and hybrid poplar (eastern cottonwood × Lombardy poplar (Populus deltoides × P. nigra)) stands but also occurred in wetlands on 10- to 12-year-old reclaimed mine sites dominated by black alder (Alnus glutinosa) and quaking aspen and a wetland dominated by speckled alder, highbush cranberry, and arrowwood .
West Virginia: American woodcocks occurred in bottomland hardwood forests dominated by sycamore (Platanus occidentalis), silver maple (Acer saccharinum), and sweetgum (Liquidambar styraciflua) and old fields with Virginia pine (Pinus virginiana), sassafras (Sassafras albidum), common persimmon (Diospyros virginiana), and black locust .
Virginia: At the Virginia National Wildlife Refuge, American woodcocks occurred in agricultural fields and mixed pine-hardwood forests of loblolly pine, black cherry, and black locust, sweetgum-yellow-poplar (Liriodendron tulipifera) forest, and wax-myrtle (Myrica cerifera) shrublands [75,82].
Illinois: American woodcocks were "incidental visitors" in sugar maple-American elm/red elm (Ulmus fulva) forest in east-central Illinois . In Jasper County, American woodcocks nested in a field of little bluestem (Schizachyrium scoparium) .
Kentucky: At the Central Kentucky Wildlife Management Area, American woodcocks occurred in old fields dominated by tall goldenrod (Solidago altissima), white panicle aster (Symphyotrichum lanceolatum), tall fescue (Schedonorus arundinaceus), Allegheny blackberry (Rubus alleghaniensis), and white wood aster (Eurybia divaricata); agricultural fields of sunflower (Helianthus spp.), corn (Zea mays), or common wheat (Triticum aestivum); and forests dominated by hickory, sweetgum, American elm, green ash (Fraxinus pennsylvanica), and eastern redcedar (Juniperus virginiana). At the Clay Wildlife Management Area, American woodcocks occurred in bottomland hardwood forests dominated by silver maple, boxelder (Acer negundo), sycamore, and white ash; upland hardwood forests dominated by Shumard oak (Quercus shumardii), chinkapin oak (Q. muehlenbergii), and shagbark hickory (Carya ovata); and corn and hay fields .
Missouri: In Boone County, American woodcocks used pastures and old fields with shrubs and young trees, including smooth sumac (Rhus glabra), multiflora rose (Rosa multiflora), coralberry (Symphoricarpos orbiculatus), eastern redcedar, cherry (Prunus spp.), and common persimmon . At the Mingo National Wildlife Refuge American woodcocks occurred in fields with beggarticks (Bidens spp.), ragweed (Ambrosia spp.), and bluestem (Andropogon spp.) .
Using expert opinion and information available in literature as of 1982, Hamel and others  determined that the habitats of American woodcocks in the South Atlantic region were as follows:
|Habitats used by American woodcocks in Virginia, North Carolina, South Carolina, Georgia, and Florida |
|Habitat||Season of use||
|Southern mixed mesic hardwoods||Breeding||---||---||M||M|
|American beech-southern magnolia (Magnolia grandiflora)||Winter||M||M||S||S|
|Bay swamp-pocosin (black tupelo (Nyssa sylvatica), redbay (Persea borbonia), sweetbay (Magnolia virginiana), loblolly-bay (Gordonia lasianthus), fetterbush (Lyonia lucida), gallberry (Ilex spp.), and cyrilla (Cyrilla racemiflora))||Breeding||---||---||M||M|
|Pond pine (Pinus serotina) pocosin||Winter||---||M||M||M|
|Longleaf pine-slash pine (P. elliottii)||Winter||M||M||M||M|
|Oak-tupelo (black tupelo/sweetgum/water tupelo (Nyssa aquatica)-baldcypress)||Breeding||---||M||M||S|
|Live oak (Quercus virginiana) maritime||Winter||---||M||S||S|
|Bottomland elm-ash-eastern cottonwood/swamp cottonwood (P. heterophylla)||Breeding||---||---||S||O|
|Loblolly pine-shortleaf pine||Winter||M||M||M||M|
|Cove hardwoods (Yellow-poplar, basswood, sugar maple, yellow buckeye (Aesculus octandra), and white oak)||Breeding||---||---||M||M|
|Sugar maple-American beech-yellow birch||Breeding||---||---||M||M|
|Red spruce-Fraser fir (Abies fraseri)||Breeding||---||---||M||M|
|*O=optimal habitat where American woodcock is likely to occur in highest frequency and/or greatest numbers; S=suitable habitat; M=marginal habitat; --- unsuitable habitat.|
South Carolina: On the Francis Marion National Forest, American woodcocks occurred in loblolly and slash pine plantations, bottomland hardwood forests including sweetgum-Texas red oak (Quercus texana)-willow oak (Q. phellos) and baldcypress-water tupelo/swamp tupelo (Nyssa biflora) communities, and pine-hardwood forests [75,80,121,122].
Georgia: In Everett, American woodcocks occurred in 1- to 15-year-old loblolly and slash pine plantations, bottomland hardwood forest including sweetgum-Texas red oak/willow oak/overcup oak (Q. lyrata)-water hickory (Carya aquatica), sweetbay-swamp tupelo-red maple, and baldcypress-water tupelo communities, mature pine-hardwood forests, and shrublands dominated by blackberry, oak saplings, wax-myrtle, and broomsedge bluestem (Andropogon virginicus) [75,80,82]. In northeastern Georgia, American woodcocks occurred in 1- to 3-year-old seed-tree clearcuts, old fields, "heavily grazed" pastures, and harvested hayfields .
South-central and Gulf Coast:
Alabama: In Lee County, American woodcocks occurred in bottomland sweetgum-yellow-poplar-southern sugar maple (Acer barbatum)-water oak (Quercus nigra) forest and sweetgum/loblolly pine-shortleaf pine forest [60,61]. On the Conecuh National Forest, American woodcocks occurred in longleaf pine forests subjected to winter prescribed fire at 1- to 10-year return intervals [67,68].
Mississippi: In the Mississippi Delta region, American woodcocks commonly occurred in sapling-stage bottomland hardwood forests dominated by sugarberry (Celtis laevigata), boxelder, sycamore, sweetgum, eastern cottonwood, and oaks. American woodcocks also occurred in mature bottomland forest dominated by large (>13.8 inches (35 cm) DBH) eastern cottonwood and in early- to midsuccessional eastern cottonwood plantations .
Oklahoma: American woodcocks occurred in bottomland hardwood forests with oak (e.g., post oak (Quercus stellata), blackjack oak (Q. marilandica), and pin oak (Q. pagoda)); elm (e.g., American and winged elm (Ulmus alata)); bluestem (e.g., broomsedge bluestem, big bluestem (A. gerardii), and little bluestem); and greenbrier (Smilax spp.) . At the Oklahoma State University Ecology Preserve, American woodcocks occurred in tallgrass prairie with Scribner's rosette grass (Dichanthelium oligosanthes), indiangrass (Sorghastrum nutans), and big bluestem interspersed with broken tracts of brush and scrub oaks. They also occurred in bottomland hardwood forest dominated by chinkapin oak (Quercus muehlenbergii), American elm, red mulberry (Morus rubra), eastern redbud (Cercis canadensis), and greenbrier .
Louisiana: Throughout Louisiana, American woodcocks occurred in longleaf-slash pine, loblolly-shortleaf pine, longleaf pine, and oak-tupelo-baldcypress forests . In south-central Louisiana, American woodcocks occurred in dense blackberry and cane (Arundinaria gigantea) thickets in bottomland hardwood forests dominated by oak (e.g., water, willow, Texas red, and cherrybark oak (Quercus pagoda)), sugarberry, elm (e.g., American and planertree (Planera aquatica)), and boxelder . In central Louisiana, American woodcocks occurred in dense stands of blackberry, Alabama supplejack (Berchemia scandens), greenbrier, cane, spice bush (Lindera benzoin), rough-leaf dogwood (Cornus drummondii), and/or Devil's walking stick (Aralia spinosa) .Texas: In Nacogdoches County, American woodcocks occurred in early-successional lowland and upland loblolly-shortleaf pine plantations, lowland early-successional hardwood forest, and mature upland pine and mixed pine-hardwood forests [8,11,41,87]. Pine plantations included a 2-year-old clearcut planted to loblolly and shortleaf pine, a pole-sized mixed pine-hardwood forest, and a sawtimber-sized mixed pine-hardwood forest. Mixed pine-hardwood forests were dominated by shortleaf pine, loblolly pine, and sweetgum . Pine plantations where American woodcocks occurred had a hardwood understory . Old fields dominated by southern dewberry (Rubus trivialis), slender yellow woodsorrel (Oxalis dillenii), perennial ryegrass (Lolium perenne), and Bermuda grass (Cynodon dactylon) were also used .
Several articles frequently cited below are reviews [16,46,70,76,79,140,141,167,178]. These include a review by the American Ornithologist's Union that was published in 1994  and the US Fish and Wildlife Service's American Woodcock Management Plan, published in 1990 . Cade  developed a suitability index model for wintering American woodcock habitats and reviewed the life history and habitat use of American woodcocks. Roberts  reviewed the ecology of wintering American woodcocks as of 1993. Gregg  reviewed the life history and habitat use of American woodcock as of 1984 as they relate to populations in northern Wisconsin. Dessecker and McAuley  provided a review of American woodcock distribution and status as of 2001, focusing on the importance of early-successional habitats to the species. Reviews of American woodcock biology and habitat with a management focus were provided in these sources: [76,140]. Earthworms are a preferred food of American woodcocks, and several studies provided reviews of factors affecting earthworm activity and abundance as of the late 1970s: [135,136,137].LIFE HISTORY:
The American woodcock has an extensive period of migration. Commencement and progress of migration are influenced primarily by day length but also by individual physiology (e.g., body mass, molt, and reproductive state), weather, moon phase, season, and year [70,79,81]. Across the North, fall migration begins in September, and most birds move during October . Cold autumn fronts appear to prompt heavy flights south [46,70,86,148,155]. In warm years, heavy flights in Maine and Minnesota occurred as late as mid-November [70,107]. Food shortage caused by drought may delay molt and prevent body fat accumulation necessary for migration, delaying migration until individuals are physiologically ready to migrate [148,153]. However, in Wisconsin some American woodcocks began their fall migration in mid-October, when fat deposits were still relatively light . American woodcocks begin arriving in Alabama, Louisiana, and Texas in late October. Most American woodcocks are on winter ranges in mid-December to mid-January [16,64,70]. Dates of heavy flights vary yearly and are more irregular in fall than spring [70,79,107,155]. Severity of winter weather may dictate how far south American woodcocks winter, and length of the growing season may limit how far north they summer [40,141].
A late snowmelt may delay arrival of migrating American woodcocks at the breeding grounds [155,178]. American woodcocks may begin migratory movements from the southernmost range in January during warm years; most American woodcocks move north by mid-February. By mid-March to mid-April, American woodcocks are located across most of the northern breeding range [16,70]. Individuals present in the South after early March are probably breeding . The entire journey from wintering to breeding grounds takes about 4 to 6 weeks . Some researchers reported that juvenile American woodcocks began migration sooner than adults and adult males arrived before adult females [14,46], but other researchers found no age or gender differences in timing of migration .
A portion (up to 62%) of American woodcocks shows fidelity to winter range [14,70]. Fidelity to breeding range appears common [46,52,107,155]. Fidelity to specific sites—such as singing grounds [35,46,107,130,133,155] and nesting sites [32,46]—within and among years also appears common [19,30,35,46,85,119,130]. Homing tendencies may be greater among adults than among juveniles and greater among juvenile males than juvenile females , although Sheldon  found no evidence to support differences in fidelity among age and gender classes. Conversely, many American woodcocks disperse [46,107,148]. Most dispersal occurs during migration [46,148]. Based upon fewer than expected captures of 2nd-year American woodcocks banded the previous year as juveniles, some researchers suspected that juvenile male woodcocks dispersed widely during their 1st year and that older woodcocks were more likely to exhibit site fidelity [35,46].
American woodcocks migrate at night [70,107]. They travel at low altitudes . American woodcocks are usually solitary, but small and temporary aggregations may occur during migration, particularly during adverse weather [70,107,178]. When weather stalls migration, high densities of American woodcocks may congregate at seeps and other protected areas where the ground is not frozen . American woodcocks may congregate to feed whenever suitable foraging sites are limited due to dry soil, ground frost, snow cover, or patchy food supply [60,70,107]. Observations suggest that American woodcocks congregate for only a few days . American woodcocks congregate in high densities during migration in certain geographic areas of the eastern region (Cape May, New Jersey; Cape Charles, Virginia; Canaan Valley, West Virginia). No congregational areas are known in the central region [107,112,113,167].
Courtship and mating: American woodcock courtship displays and nesting span a 6-month period beginning in January in the South and extending into June in the North. The onset and extent of American woodcock breeding is influenced by temperature [70,141]. Male American woodcocks begin displaying on wintering grounds, sometimes as early as December when weather is warm [40,60,89], and continue displaying during spring migration and upon arrival on breeding grounds [46,178]. On the breeding grounds, time between first and last displays averaged 6 weeks , but the number of displaying males typically peaked during a 1- to 2-week period after arrival (e.g., [111,155]). Males in the North continue to display until most chicks are full grown [70,93].
Male American woodcocks perform courtship displays that attract females to their display sites, called singing grounds, where copulation occurs [107,155]. These reviews describe the courtship display of male American woodcocks, including elaborate flight pattern and vocalizations: [31,38,70,107,125,155,178]. Males move from diurnal habitats to the singing ground at dusk. They may remain there overnight or move to separate nocturnal habitats. At dawn, they move back to diurnal habitats .
American woodcock singing grounds are typically open or brushy areas in early-successional stages (see Singing grounds) [16,38,125,178]. Males usually use >1 singing ground but often use 1 singing ground more often than others [130,159]. An individual male may use the same singing grounds for many years . American woodcock males are territorial only at singing grounds and females are not territorial [70,107,155]. The male's territory consists of the area used for display and copulation [133,155]. Territories are defended via aggressive vocalizations and behavior . Females leave diurnal habitats at dusk and dawn to visit displaying males at singing grounds, often remaining in protective cover at the edge of the singing ground . A given female may visit multiple males per evening, and multiple females may visit a given male [105,159,173]. Wenstrom  reported that females did not return to singing grounds after nesting , whereas McAuley and others  reported that females visited males at singing grounds throughout the breeding cycle (i.e., from prenesting to brood rearing). Visitation was sporadic, however, and females visited singing grounds during only a small proportion (14%) of their crepuscular activity, often remaining in nest and brood cover at night .
Many male American woodcocks do not display [46,60,175]. Studies suggest that nondisplaying males may be subordinate to displaying males and may display after the dominant individuals are removed [35,155,175]. Subadult males become sexually active at the same time as adult males (see Reproduction and development), yet adults are more common on established singing grounds during the first part of the breeding season. This suggests that old males establish and maintain territories more successfully than young males, perhaps because old males arrive earlier and claim territories sooner or are better able to defend territories than young males [35,60,105,140,175]. For more information on this topic, see the review by Keppie and Whiting .
Reproduction and development: The American woodcock is one of the earliest breeders of all North American birds [46,104,140]. Nesting commences in early spring before vegetation greens [70,104,111]. It begins in late January and February in the South and in late April and May in the North . Peaks in nesting coincide with or occur shortly after peaks in the males' displays . Nesting typically peaks over 2 weeks [46,93,175]. Peak dates of hatching vary with latitude and weather [70,107,155].
Females lay an average of 4 eggs [46,70,93,107,178]. Eggs are incubated for 20 to 22 days [46,70,107,173,178]. Only females incubate the eggs and care for young [46,107]. They are extremely reluctant to flush from their nests. Disturbance may prompt nest desertion, particularly when clutches are incomplete and during the first few days of incubation [46,107,155]. Female American woodcocks do not rear more than one brood per nesting season [107,155]. However, they typically renest if a nest is unsuccessful [35,70,93,104,107].
All viable eggs within a nest hatch within 4 to 5 hours [70,107]. Young weigh about 10 to 15 grams at hatching . They are precocial and can leave the nest within a few hours of hatching [70,107]. Young grow rapidly [32,70,93]. The growth rate of female chicks (about 6 g/day) is higher than the growth rate of male chicks (about 5 g/day) [32,52]. At 2 days of age, young chicks may forage over 300 feet (90 m) from their natal nest  (see Broods). Two-week old chicks are fledged and able to take short flights [107,177]. Four- to 5-week-old chicks are about adult size and are strong flyers [70,155]. American woodcock broods break up soon after reaching adult size. Estimates of brood period length vary. Reviews state that broods break up about 4 to 8 weeks after hatching [46,79,155,173,177,178].
Juvenile American woodcocks molt soon after brood break-up, from March to August, depending upon latitude. At this time, 3 age classes can be identified: juveniles (hatching-year or immature), subadults (hatched in the preceding year), and adults (hatched before the preceding year). After molt, only juveniles and adults can be separated by age . The age and gender of American woodcocks can be determined by a combination of wing plumage characteristics, bill length, and body size [107,140,155]. Although there is some overlap, adult females tend to be larger and weigh more (5.6-8.5 ounces (160-240 g)) than adult males (4.4-6.7 ounces (125-190 g)) . For a review of methods to determine age and gender, see Roberts . American woodcocks are sexually mature by 10 to 12 months. Both genders breed in their first spring [70,104,155,178], although older individuals of both genders may breed earlier in the year (see Courtship and mating) .
Reproduction, growth, and survival of American woodcock eggs and young are influenced by weather, maternal age, and year [32,35,46]. At the Moosehorn National Wildlife Refuge, old (>2 years) females were apparently more successful in hatching a clutch than younger females , and growth rates were slower for chicks of young females than old females (P=0.013) . Old females had larger broods (3.5 chicks) on average than young females (2.9 chicks), but year effects were more important in determining brood size and chick survival than female age . No differences in survival until fledgling were evident between broods of old and young females .
Molt: Juvenile American woodcocks molt all feathers except primary and outer secondary wing feathers in their first summer, whereas adults molt all feathers. Molt may take several weeks to complete . Adult American woodcocks lose weight during molt (Owen and Krohn 1973 cited in ). Owen and Morgan  found that 3 adults increased diurnal activity during molt and speculated that adults may need to increase the amount of time feeding during molt to meet the energy requirements of feather replacement. The molt of juveniles, being incomplete, probably demands less energy than the molt of adults, but also appears to influence activity levels . Increased energy demands during molt may cause shifts in habitat use as well as activity (see Breeding-season diurnal habitats).
Life span and survival: Estimated mean life spans for American woodcocks in Wisconsin were 1.5 and 1.6 years for males and females, respectively . Blankenship  estimated an average life span of 0.9 year for American woodcocks of mixed ages and genders in Michigan. In Massachusetts, the average life expectancy of male American woodcocks reaching adulthood was 1.8 years (Sheldon 1956 cited in ). In Wisconsin, the oldest male was 8 years old, and the oldest female was 11.4 years old . Mendall and Aldous  reported that the maximum age of an American woodcock was 12.5 years based on banding returns conducted in Maine.
Throughout its range, American woodcock survival appears to be high during all life stages. Nesting and hatching success is high. At the Moosehorn National Wildlife Refuge, success of initial nests and renests was 50% and hatching success was 95%. Given a 50% nest success and a high probability of renesting, the authors estimated that 75% of nesting females may successfully hatch clutches in any given season . Gregg  speculated that because a high proportion of first nests are successful, renesting may play only a minor role in determining annual recruitment. High nesting success may help compensate for the American woodcock's small clutch size .
|Hatching (percentage of eggs in a nest successfully hatched) and nest (percentage of nests hatching at least 1 egg) success of American woodcocks|
|Location||Hatching success (infertility rate) (%)||Nest success (%)|
|Moosehorn National Wildlife Refuge, Maine||67 (2)||75 |
|Moosehorn National Wildlife Refuge, Maine||95||50 |
|High Island, Michigan||85||89 |
|Eastern Minnesota||65||86 |
|Portage County, Wisconsin||76 (10)||73 |
|Northern Wisconsin||61 (4)||47 |
American woodcock chick survival appears high during the brood period (from hatching until brood break-up) . Survival rates of chicks during the brood period was 89% in Portage County, Wisconsin , 59% to 90% at the Moosehorn National Wildlife Refuge [32,35,107], and 84% in northern Wisconsin . During the brooding period, chick mortality may be highest after fledging. In Alabama, 31% of chicks died, of which 91% died after fledging. The authors attributed the high mortality to increased activity and visibility, which may make them more vulnerable to predators and accidents. However, the authors could not discount the possibility of research methods lowering the apparent survivability of fledged chicks .
Typically, survival rates among age and gender classes are similar [77,77,80,83,95,96,102,120], although sample sizes are often small and the power to detect a difference is low in most studies. However, some researchers report that on average, females had higher survival rates than males and adults had higher survival rates than juveniles [25,34,155]. Longcore and others  found that survival rates of males and females were similar but that predation of males (48%) by raptors was higher than that of females (9%), whereas mammals killed females (45%) more frequently than males (15%). Researchers speculated that because displaying adult males are conspicuous, these males may be subject to higher predation rates during the breeding season than females or juveniles [35,155].
Longcore and others  estimated survival of adult male American woodcocks at the Moosehorn National Wildlife Refuge during the breeding period (1 April-15 June) for 3 consecutive years. Using data from this and other studies, the authors estimated survival for other periods of the annual cycle. Mean survival rate was lowest during the wintering period and highest during the postbreeding period .
|Survival estimates of adult male American woodcocks for different periods of the annual cycle. Estimates were derived from several studies throughout the American woodcock's range .|
|Spring migration (16 February-31 March)||0.881|
|Breeding (1 April-15 June)||0.789|
|Postbreeding (15 June-20 October)||0.923|
|Hunting and fall migration (21 October-14 December)||0.853|
|Wintering (15 December-15 February)||0.647|
In general, survival rates appear to be lower in winter than during other seasons [77,83,102,120]. As of this writing (2010), it is not clear why survival is lowest in winter. Reduced habitat quality on wintering grounds may contribute to lower survival in winter. American woodcocks often forage in exposed crop fields on wintering grounds (e.g., [19,40,160]) and may experience greater predation rates in these areas. However, it is not known whether American woodcock survival or reproduction differs by habitat . For more information, see Diseases and Sources of Mortality.
Population density: Reliable estimates of local American woodcock population densities are difficult to obtain . Common methods used in American woodcock studies do not produce equal proportions of American woodcocks in each age and gender class due to differences in behavior . These differences are confounded by daily and year-to-year variation in the number of American woodcocks detected by each method due to differences in moonlight, humidity, cloud cover, and precipitation [35,40,154]. Flush rates—usually calculated as the number of flushes per man-hour or dog-hour—and frequency of occurrence of sign, such as probe holes, feces, feathers, or nests, are common methods of determining local American woodcock population densities, but in some cases, flush counts and frequency of occurrence of sign yield different results [132,179], making interpretation of results difficult. Because American woodcocks may be scattered, concentrated, or absent in a given habitat depending on the time of year, the prevailing weather, or the condition of the habitat, Sheldon  compared American woodcock population densities to the "crests and troughs of ocean waves" and considered American woodcock density estimates to be "meaningless" and "unpredictable" because "there is no regularity in time and areas where birds gather". Furthermore, because American woodcock habitat often consists of disjunct "pockets" of cover within habitats, calculating density estimates within habitats or over a large area is generally not appropriate . For more information on local American woodcock population density estimates in different habitats, see Preferred Habitat.
Home range and movements:
Home range: The American woodcock's home range consists of separate diurnal and nocturnal "activity centers". American woodcocks move to and from these activity centers during crepuscular flights of varying length. Thus, total home range sizes are typically much larger than combined activity centers, which tend to be small. American woodcocks shift their use of diurnal and nocturnal areas periodically, varying use of an area from a few days to weeks  (see Preferred Habitat).
According to a review, male American woodcocks in the North typically have larger home ranges than females, and home range sizes are similar among age classes . At the Moosehorn National Wildlife Refuge, average home range sizes did not differ significantly by age or gender, although males (adults: 30 acres (74 ha); juveniles: 27 acres (67 ha)) tended to have larger home ranges than females (adults: 17 acres (42 ha); juveniles: 16 acres (40 ha)), regardless of age . However, in northern Wisconsin, adult female American woodcocks (56 acres (138 ha)) had substantially larger home ranges than adult males (16 acres (40 ha)), and juvenile females (30 acres (74 ha)) had larger home ranges than juvenile males (21 acres (52 ha)) . In Carlton County, Minnesota, male and female American woodcocks monitored for about 3 weeks during summer had similar home range sizes, which averaged 14.8 acres (6.0 ha). Within home ranges, average diurnal (0.25 acres (0.10 ha)) and nocturnal (<0.02 acres (0.01 ha)) activity centers were small . In Centre County, Pennsylvania, activity centers of male American woodcocks ranged from 0.12 to 2.42 acres (0.05-0.98 ha) and home ranges ranged from 0.7 to 423 acres (0.3-171 ha) .
In the South, home range sizes vary substantially among individuals. Five American woodcocks of mixed ages and genders wintering in Lee County, Alabama, had 27- to 52-acre (11-21 ha) home ranges and 3- to 7-acre (1-3 ha) activity centers . In a related Lee County study, 17 wintering American woodcocks of mixed ages and genders had home ranges from 16.1 to 60.0 acres (6.5-24.3 ha), diurnal areas ranging from 2.7 to 55.6 acres (1.1-22.5 ha), and activity centers (67% of all locations ) ranging from 1.0 to 14.1 acres (0.4-5.7 ha). Home ranges averaged 49.4 acres (20.0 ha) for adult females, 27.7 acres (11.2 ha) for adult males, 26.4 acres (10.7 ha) for juvenile females, and 41.8 acres (16.9 ha) for juvenile males .
At the Moosehorn National Wildlife Refuge, home range sizes were similar among age and gender classes, but the sizes of diurnal home ranges varied significantly among forest types (P=0.016), with larger diurnal home ranges in aspen forest (89 acres (36 ha)) than speckled alder (27 acres (12 ha)) and balsam fir (27 acres (11 ha)) forests. American woodcocks also had smaller diurnal home ranges in sapling (<10 cm DBH; 37 acres (15 ha)) stands than stands with larger trees (≥10 cm DBH; range: 37-91 acres (18-30 ha)) (P=0.050). The authors suggested that American woodcocks had smaller home ranges in balsam fir forest because more of this habitat was available in the sapling stage .
Movements: American woodcocks fly or walk between diurnal and nocturnal habitats at dusk and dawn [40,61,70,85,85,119,155,173]. During the day, they typically use forests and shrublands, using openings at night. However, some American woodcocks remain in forests and shrublands at night. Others move to openings but do not remain there the entire night (see Preferred Habitat). Whether an individual American woodcock makes crepuscular movements depends in part upon the individual's physiological condition. In Terrebonne County, Quebec, a significant peak in crepuscular flight activity of American woodcocks of mixed ages and genders was observed in late June and early July, which was followed by a significant decrease in flight activity until mid-September. The decline in flight activity coincided with molting (P<0.05 for all variables) . Owen and Krohn (1973 cited in ) also reported a decline in crepuscular flight activity in August, coincident with molting. The increased nutritional demands of feather growth during molt may cause a wane in crepuscular activity during late summer, and American woodcocks may remain in diurnal habitats at night to feed and/or conserve energy .
Daily movements also differ according to an individual's age and gender. Limited evidence suggests that adults may be more active during the breeding season than juveniles [30,119]. Other studies report that juveniles, particularly males, are more active than adults . In Penobscot County, Maine, juvenile American woodcocks moved from diurnal habitats to nocturnal habitats significantly earlier in the day than adults, and females preceded males (P<0.10 for all variables) . In a related study in Penobscot County, it was common (23% of observations) for juveniles to land on a field at night, remain for a few minutes, and then fly to a different location , although it was rare (4% of observations) for adults to exhibit this behavior . Similar behavior patterns were observed by Krohn  in the same area. In Carlton County, Minnesota, juvenile male and female American woodcocks tended to fly shorter distances from day to night cover but flew on more evenings than adult (>1-year-old) females . American woodcocks may search for sites with suitable microhabitat cover before settling for the night, which may require them to make several flights over an area or shift between habitats many times and do some searching on the ground .
Beginning and ending times of American woodcock crepuscular movements, including courtship activities, are related to sunset, sunrise, moon phase, and weather (temperature, wind speed, humidity, precipitation, and cloud cover). The relationships among these variables suggests that light intensity triggers initiation and culmination of these movements [9,40,60,85,107,119,155,180,180]. In northeastern Georgia, not all individuals moved between diurnal and nocturnal habitats, but when they did, movements made during the full and last-quarter moons were shorter than those made during the new and first-quarter moons (P=0.003), possibly to avoid predators during bright moon phases . Glasgow  also observed that fewer American woodcocks used fields during full moons. In Massachusetts, American woodcocks abandoned openings at night when it was windy, cold, or when the moon was bright . American woodcocks are more active and perform courtship displays for longer periods of time at dawn and dusk on warm, clear nights; adverse weather such as below freezing temperatures, high winds, heavy rain, and fog may result in shorter courtship periods or cessation of courtship activities [60,107,133,155].
American woodcocks typically move short distances between diurnal and nocturnal habitats, but long-distance travels are occasionally observed. In Nacogdoches County, Texas, maximum flight distances were 7,358 feet (2,243 m) by males and 5,692 (1,735 m) by females, but 84% of movements by both genders were <100 feet (30 m) . A review states that it is common for adult males to move farther than adult females and for juvenile males to move farther than juvenile females . However, in most studies mean movement distances among ages and genders were similar [7,8,147].
|Mean distances (m) moved by American woodcocks between diurnal and nocturnal habitats|
|Adult male||Adult female||Juvenile male||Juvenile female|
|Winter (December-February)||northeastern Georgia||311||275||625||179 |
|Fall & winter (November-April)||Nacogdoches County, Texas||393||319||no data||no data |
|Breeding (June-October)||Moosehorn National Wildlife Refuge, Maine, at dusk||387||510||560||359|
|Breeding (June-October)||Moosehorn National Wildlife Refuge, Maine, at dawn||254||293||544||417 |
|Breeding (June-September)||Penobscot County, Maine||
170 (both genders) 
332 (both genders) 
Predators: Predators may be the greatest single cause of nest losses and account for the most mortality of young and adult American woodcocks . American woodcock eggs, young, and adults are preyed upon by numerous predators. Eggs are consumed by domestic dogs (Canis familiaris) [97,107,178], striped skunks (Mephitis mephitis), spotted skunks (Spilogale putorius) , red squirrels (Tamiasciurus hudsonicus) [97,107], Virginia opossums (Didelphis virginiana) , crows (Corvus spp.) [46,178], and snakes (e.g., black snake (Coluber constrictor)) [70,97,107,178]. Young and adults are consumed by domestic cats (Felis catus) [70,97,107,178], domestic dogs , bobcats (Lynx rufus) , American minks (Mustela vison), northern raccoons , red foxes (Vulpes vulpes), and common gray foxes (Urocyon cinereoargenteus) [80,97,178]. Avian predators in particular may cause high mortality of young and adults . Avian predators include owls (e.g., great horned owl (Bubo virginianus), barred owl (Strix varia), and long-eared owl (Asio otis) [46,80,96,97,107,155,177,178]), hawks (e.g., sharp-shinned hawk (Accipiter velox) [96,97,107,177], goshawk (A. gentiles) [47,96,107,177], and Cooper's hawk (A. cooperii) [93,102]), peregrine falcons (Falco peregrinus), northern harriers (Circus cyaneus) ), bald eagles (Haliaeetus leucocephalus), and shrikes (Lanius spp.) [155,164].
Diseases and parasites: Mendall and Aldous  speculated that diseases and parasites are "probably of no practical importance". Sheldon  agreed, but noted the difficulty of documenting mortality due to these causes. Diseases such as reovirus, gregarine infection, and malaria have been reported rarely, and parasites such as tapeworms (e.g., Hymenolepis spp. and Anomotaenia spp.), roundworms (e.g., Filaroidae and Trichostrongtloidae), flukes (e.g., Strigeidae and Echinostomatidae), and lice (e.g., Mallophage) frequently occur on American woodcocks [9,107,178]. See the following for reviews of diseases and parasites affecting American woodcocks: [70,155].
Weather: Severe weather such as prolonged cold, wet weather, snowstorms, drought, and flooding may cause direct mortality of American woodcocks via exposure to the elements or cause indirect mortality by starvation or by limiting the availability of earthworms, thereby forcing individuals to travel farther in search of food or to feed in places where they are exposed to predators [35,40,46,107,153,155,168,178]. Many researchers report little or no evidence of American woodcock mortality due to weather [83,93,177]. Although weather-related mortalities are often difficult to detect [93,107,128], weather is considered a major contributor to mortality only when extreme [93,107].
Temperature and wind in combination affect the timing of spring and fall migration . Usually, American woodcocks can migrate before adverse conditions cause death. However, mortality may increase during fall migration if the molt is delayed and American woodcocks are unable to accumulate the necessary fat reserves for migration because of limited food resources . See Migration for more information.
Severe weather during the breeding period may be particularly detrimental to American woodcock survival because American woodcock energy requirements peak during this time [128,150]. Although evidence from Owen and Krohn (1973 cited in ) indicated that American woodcocks usually arrive at breeding grounds with enough energy reserves to endure short periods of inclement weather or food shortage, extended periods of unfavorable weather combined with increasing energy requirements for breeding may be deleterious [46,96,128,150]. Adverse weather (precipitation and high winds) may decrease the frequency and duration of singing male activity (see Movements), and snow cover during the breeding period may delay nesting and limit available nesting cover (see Nests) . Snowstorms during nesting may result in abandonment or increased predation of clutches [46,107]. Mortality of eggs may be caused by freezing temperatures . Nests may also be abandoned due to flooding . Chicks can die of exposure if temperatures remain low and are accompanied by precipitation for an extended period [35,46,150,178]. At the Moosehorn National Wildlife Refuge, chick production and total precipitation during brood-rearing were negatively correlated (r= -0.985, P<0.05) . Because chicks have few energy reserves from which to draw upon and require increasing amounts of earthworms to maintain their rapid growth, they may need a more consistent food supply and thus be more vulnerable to weather changes that affect earthworm availability . This is supported by observations of decreased juvenile survival during drought [35,153].
Many researchers reported that American woodcocks responded to adverse weather conditions by shifting habitats, diet, and/or foraging frequency [40,70,107,132,137,155,168,178]. American woodcocks cannot probe in hard, droughty or frozen soils. Extremely cold winter temperatures in the South caused soil to freeze and American woodcocks to move. Flooding on wintering grounds caused American woodcocks to relocate to drier, more exposed areas . Energy requirements of all ages and genders increase during molt , and use of nocturnal habitats by molting birds at the Moosehorn National Wildlife Refuge declined during drought, apparently because it was no longer energetically feasible for American woodcocks to make flights to and from nocturnal roosting areas . For more information, see Preferred Habitat. During periods of adverse weather, usable habitats may be few . The habitat components that are critical for survival during periods of adverse weather are not thoroughly understood , and information on American woodcock survival in different habitats under different types of weather is restricted to anecdotal evidence as of the this writing (2010). Shifts from the use of hardwood forest to conifer forest during a drought in Maine suggest the importance of conifer forest during drought . Seeps, riparian zones, and wetlands may also be important during cold weather  (see Migration).
Climate change: Because American woodcock reproduction and survival may be heavily influenced by extremes in local temperatures, precipitation, and snow depths, they are potentially affected by large-scale climatic fluctuations such as the El Niño Southern Oscillation and the North Atlantic Oscillation (review by ). Any decline in American woodcock populations caused by loss in habitat quality and quantity is likely accentuated by weather extremes . Because global climate change may lead to a higher frequency of extreme weather events (review by ), it is likely to negatively affect American woodcocks.
The geographic distribution of the American woodcock is, in part, limited by temperature and precipitation patterns [40,162]; thus, there is potential for the American woodcock to alter its distribution as a result of climate change. Thogmartin and others  speculated that the expansion in the distribution of breeding American woodcocks to the north and west, which was first noted in the late 1970s, may have been as much a response to changes in climate as to changes in forest management practices. For more information, see Status and threats.
Other sources of mortality: Roads and automobiles [9,46,95,107,155,178], fires , and hunting [97,102,107,178] contribute to American woodcock mortality. Nests are sometimes trampled by cattle (Bos taurus), but American woodcocks nest in pastures infrequently, so trampling is probably not substantial . American woodcocks fly at low altitudes , often just above the treetops or down flight lanes such as canals or woods roads , so they are particularly susceptible to flight obstructions such as power lines, buildings, and trees [9,46,86,95,97,107,177]. American woodcocks are susceptible to secondary poisoning when they eat invertebrates exposed to pesticides. Several studies provide information on pesticide residues found in American woodcocks and on pesticide-related mortality: [70,121,155,157,175].
Human disturbance may be detrimental to American woodcocks. Disturbing a female American woodcock at her nest may cause the female to abandon her nest (see Reproduction and development) [52,107,155]. Anecdotal information suggests that American woodcocks may alter their behavior after disturbance [14,30,40,85,118,130,154]. Frequent disturbance may increase vulnerability to predation or other sources of mortality .
Habitat loss and degradation may contribute to American woodcock mortality. A lack of appropriate vegetation cover may lead to increased predation. As the habitat area shrinks, American woodcocks may be forced into the best available habitats at higher densities, which may lead to increased predation, a strain on food resources, and possibly increased hunting pressure . For more information on this topic, see Status and threats.PREFERRED HABITAT:
American woodcocks tend to use 2 different habitats on a daily basis: nocturnal and diurnal habitats. In general, vegetation structure appears to be a better indicator of diurnal and nocturnal habitat use by American woodcocks than plant species composition [11,12,14,36,46,63,70,89,129]. However, plant species composition in some cases may be an indicator of suitable habitat . Diurnal habitats are typically forests or shrublands with complex vegetation structure and are principally used as foraging and resting sites by both genders and as nesting and brooding sites by females. American woodcocks prefer diurnal habitats with moderate sapling tree, shrub, and ground cover and scattered patches of bare soil and deciduous leaf litter. Extremely open and extremely dense habitats are avoided. Nocturnal habitats are sometimes the same as those used during the day but also include openings with scattered patches of woody vegetation. They are principally used for courtship, feeding, and resting (e.g., [16,40,46,70,93,97,158,167,173,179]).
Forests with moderate overstory, understory, and ground cover probably help American woodcocks evade predators because they provide hiding cover, restrict predator movement and use, or facilitate escape when detected . Very dense forest habitats may inhibit American woodcock flight and increase predation, and very open habitats may not provide adequate concealment . Dense ground cover limits access to soil, while patchy bare ground likely makes probing for earthworms and other soil invertebrates easier [11,16,63,93]. Tree, shrub, and ground cover also influence food resources of soil invertebrates and influence soil moisture, temperature, and pH, which affect earthworm abundance (see Earthworm availability) . Because American woodcocks primarily feed on detritus-feeding earthworms, some litter is typically present in preferred habitats, but dense litter may hinder probing [16,79]. Openings may make it easier to fly around obstacles than forests . They may also improve visibility and mobility, and thus protection from predators [11,70,173,179]. These factors may explain American woodcock's use of openings at night and close affinity to forest edges during the day . Hale and Gregg  suggested that American woodcock's association with edge may be a reflection of its need for a well-developed understory.
Diurnal habitats: American woodcocks use a variety of habitats during the day. Diurnal habitats in breeding and winter ranges vary, although structural characteristics of these habitats are often similar, with very dense and very open habitats least preferred or unused . Diurnal habitats of females with nests or broods may differ from those of males or nonreproductive females (see Nests and Broods).
Breeding-season diurnal habitats: During the breeding season, American woodcocks use a variety of habitats during the day. Early- to midsuccessional hardwood and mixed hardwood-conifer forests interspersed with shrubs and tree saplings, particularly alder and aspen, are frequently used, as are older stands with a dense understory [16,26,63,70,155].
Habitat shifts: Habitats used vary throughout the breeding season, and shifts in habitat use correspond with weather and American woodcock activity and physiology [107,114,132,171,179]. Commonly, the breeding season is divided into breeding (courtship and mating), nesting and brood-rearing, molt, postmolt, and premigratory-staging periods . At the Moosehorn National Wildlife Refuge, American woodcocks used well-drained sites, particularly hardwood forests, during spring breeding through brood rearing (15 April-15 July), and used lowland areas, particularly alder forests, during molt and premigratory staging (15 July-15 September). Molting coincided with long periods of dry weather. American woodcocks became secretive and sought lowland wet areas such as dense alder thickets during molt [107,132]. From postmolt until migration (30 October-15 November), American woodcocks were notably less secretive and shifted among habitats frequently , but use of alder habitats remained high, peaking just prior to migration [107,132].
Similarly, Rabe  found that use of alder habitats increased late in the breeding season. He concluded that American woodcocks beginning molt shifted to habitats with dense understories, probably in response to shifts in food supply caused by changes in soil moisture . In spring, flush rates of solitary American woodcocks were highest in midsuccessional (10-20 years old) aspen forests and lowest in young (<10 years old) alder forests. Use of midsuccessional aspen forests remained high through molt. Flush rates during molt were moderate in midsuccessional mixed-hardwood and alder forests and low in young (<10 years old) aspen forests. In early September during premigratory staging, use of young aspen and alder forests exceeded that of midsuccessional aspen and mixed-hardwood forests. During migration, all habitats were used equally .
Several studies reported that American woodcock habitat use shifts in accordance with seasonal and annual changes in soil moisture due to weather, with American woodcocks avoiding very dry and very wet sites [46,93,173]. In northern Wisconsin in summer and early fall, American woodcocks spent more time on average in aspen than any other forest type except during a drought year, when use of alder surpassed aspen. The drought may have forced American woodcocks to move to lowland sites in order to obtain earthworms . In Michigan, American woodcocks apparently moved from upland sites used in late spring and early summer to moist lowland areas such as stream bottoms from late summer until migration . Wenstrom  observed a similar pattern in Carlton County, Minnesota. In early spring in Terrebonne County, Quebec, American woodcocks concentrated in seepage areas on south-facing slopes where snow had melted. After spring snowmelt, they frequented hardwood and mixed hardwood-conifer forests and used alder infrequently (P<0.01). Females selected drier, upland sites for nesting. In summer after broods fledged, American woodcocks significantly increased use of hardwood forests (P<0.01) and increased use of alder and mixed hardwood-conifer forests slightly. In fall, during migration and premigratory staging, American woodcocks shifted away from hardwood and mixed hardwood-conifer forests and used alder habitat more frequently (P<0.01). Although precipitation volume directly affects soil moisture and earthworm availability (see Earthworm availability), habitat shifts seemed unrelated to earthworm availability. The authors cautioned, however, that during dry years, higher earthworm abundance in alder forests than in other forests would likely benefit American woodcocks .
At the Moosehorn National Wildlife Refuge, during a period of average rainfall, American woodcocks used speckled alder and mixed hardwood-conifer forests significantly more than conifer forest. Earthworm abundance in speckled alder and conifer forests did not vary significantly from June to August, but earthworm biomass in speckled alder habitat exceeded that in conifer forest consistently throughout summer (P<0.05 for all variables). During a drought, American woodcocks shifted from alder to conifer forests, possibly because earthworm biomass in the 2 habitats was comparable and conifer habitats were better shaded and lost less moisture . There are many other cases where earthworm abundance and/or biomass, which are influenced by soil moisture, were related to American woodcock habitat use. For more information on this topic, see Forage-site selection.
American woodcocks rarely remain in the same habitat throughout the breeding period, but several cases of this were reported. Weeden  found that birch and alder habitats were preferred throughout the breeding season. No seasonal differences were detected in American woodcock habitat use within and among years during a 3-year study in Oswego County, New York, with American woodcocks consistently selecting alder habitats over other habitats . In Huntingdon County, Pennsylvania, American woodcocks consistently preferred diurnal habitats dominated by gray dogwood regardless of season, and they apparently preferred sparse ground cover regardless of plant composition . Habitat shifts may not occur if American woodcocks are responding to habitat attributes other than plant composition. In Portage County, Wisconsin, alder habitats were apparently used similarly in spring and summer but upland conifer forests were used more in summer than spring. The author suggested that high sapling and shrub density was more important to American woodcocks in spring than summer, and in summer, denser canopy cover compensated for lower understory cover .
Habitat structure: In general, American woodcocks prefer diurnal habitats with an intermediate range of sapling tree and shrub cover. In central Pennsylvania, they preferred diurnal sites with tall (4.1-8.2 feet (1.25-2.5 m)) shrubs providing moderate cover (≥32%); intermediate sapling density (5,200-7,400 saplings/ha); and intermediate canopy closure (75-84%) relative to random sites. They avoided areas with short (<4.1 feet tall) or tall shrubs providing sparse cover (<12%); sparse saplings (<1,500 saplings/ha); and either very high (≥90%) or low (<50%) canopy closure (P<0.05 for all variables) . Similar results were found in another study in central Pennsylvania . American woodcocks at Houghton Lake State Forest used diurnal habitats with 20 to 360 mature trees/acre; 810 to 4,860 saplings/acre; and 3,000 to 5,580 shrub stems/acre . In Carlton County, Minnesota, female American woodcocks used diurnal habitats with tree (>3.9 inches (10.0 cm) DBH) densities from 123 to 617 stems/ha; sapling (1-3.9 inches (2.5-10.0 cm) DBH) densities "with a range similar to tree densities"; and shrub (<1 inch DBH) densities ranging from 12,597 to 86,450 stems/ha most frequently . Shrub density and cover were greater in 8 of 10 high-use sites of juvenile females than in surrounding sites. Shrub cover ranged from 24% to 81%, but shrub cover was ≥75% in 8 high-use areas. Herb cover in the 8 high-use areas was less than that in surrounding areas. The other 2 high-use areas had relatively sparse shrub cover (range: 24-49%) but high herb cover compared to surrounding sites . In Oswego County, New York, diurnal sites had greater overstory (3,000 trees/ha) and understory (16,000 stems/ha) densities and lower mean canopy height (26 feet (8 m)) than random sites . In Centre County, Pennsylvania, adult male American woodcock diurnal sites were predominantly young forest stands with dense small trees (1,650 small trees/ha), dense shrub understories (119,200 shrubs/ha), and abundant earthworms (8 earthworms/m²) (P<0.01 for all variables) .
American woodcocks also prefer diurnal habitats with an intermediate range of ground cover. Liscinsky  stated that ideal American woodcock habitat in Pennsylvania had <25% ground cover, although most studies report denser ground cover in diurnal habitat. In Terrebonne County, Quebec, ground cover (0.3-3.0 feet (0.1-0.9 m) tall) was moderate (46% cover ) in "good" diurnal habitat and either extremely dense or extremely sparse in "poor" diurnal habitats. The authors suggested that <30% ground cover may not provide protection from predators, but cover >60% may interfere with mobility . American woodcocks at Houghton Lake State Forest used diurnal habitats with 33% to 65% ground cover .
American woodcocks prefer diurnal habitats with some bare ground and litter, although the actual amount required varies. Bare ground provides access to soil invertebrates, but some leaf litter is required to provide food for soil invertebrates. In Terrebonne County, Quebec, "good" diurnal habitats for American woodcocks had more bare ground (87%) than "poor" habitats (56%) . In central Pennsylvania, American woodcocks preferred diurnal sites with bare ground cover ranging from 12% to 17% and avoided areas with <2% bare ground cover relative to random sites (P<0.05) . In Oswego County, New York, diurnal sites had more bare ground (53%) and sparser leaf litter (41%) than random sites (bare ground: 6%; leaf litter: 74%) . Bare ground in diurnal habitats in Penobscot County, Maine, averaged 56%  and ranged from 36% to 67% at Houghton Lake State Forest . In Centre County, Pennsylvania, adult male American woodcocks used diurnal sites with shallower litter depth (1.3 inches (3.2 cm)) than random sites (1.5 inches (3.8 cm)) (P<0.01) .
Diurnal habitats on the breeding range are typically close to an opening. In Maine and New Brunswick, American woodcock diurnal locations averaged 23 feet (7 m) from an opening . In Oswego County, New York, most American woodcocks flushed during the day were within 100 feet (30 m) of a forest edge . For more information on this topic, see Movements.
Winter diurnal habitats: On wintering grounds, American woodcocks appear to prefer mid- to late-successional forests such as bottomland hardwood forests and upland pine and pine-hardwood forests during the day, although stands in seral stages ranging from clearcut to mature are used [16,26,70,122,141,155]. Bottomland hardwood forests with a moderate to dense hardwood understory are particularly important to American woodcocks on wintering grounds [54,59,79,167]. American woodcocks use loblolly, shortleaf, and longleaf pine forests. Within these forests, American woodcocks are often associated with hardwood-dominated riparian drainages and seeps [26,141,159]. In the South, woody vines such as greenbriar, grape (Vitis spp.), Japanese honeysuckle (Lonicera japonica), Alabama supplejack, poison-ivy (Toxicodendron radicans), and trumpet creeper (Campsis radicans) are particularly important components of the understory [140,141]. Shrublands appear to be equally important in both breeding and winter ranges [61,75].
Habitat structure: In winter, American woodcocks select diurnal habitats with moderate to dense sapling, shrub, and vine cover. Sites with sparse understories are avoided. In Lee County, Alabama, wintering American woodcocks of mixed ages and genders preferred bottomland hardwood and mixed hardwood-pine forests during the day. Sapling hardwood forests and pine plantations were least preferred. Total stem densities in bottomland hardwood (6,422 stems/ha) and mixed hardwood-pine (8,440 stems/ha) forests were intermediate in value compared to total stem densities for sapling hardwood (13,511 stems/ha) and pine plantations (range: 2,915-4,500 stems/ha). Diurnal habitat selection was not related to the percent of open ground cover, which ranged from 31% to 64% . In the Mississippi Delta region, more wintering American woodcocks were flushed during the day from sapling and mature bottomland hardwood forests than pole bottomland hardwood forest or sapling-pole eastern cottonwood plantations (P<0.05). This was attributed to moderate to dense blackberry and vine cover in the understory of sapling and mature forests and a sparse understory in pole stands and cottonwood plantations .
|Percent of transects from which American woodcock were flushed in 2 forests types in the Mississippi Delta region |
|Forest type*||Percent of transects|
|Bottomland hardwood forests|
|Sapling and pole cottonwood plantations||3%|
|*Sapling: ≤10.2 cm DBH; pole: 10.4-22.9 cm DBH; mature: >22.9 cm DBH.|
On the Francis Marion National Forest, American woodcock diurnal flush sites were primarily in mid- to late-successional bottomland hardwood stands. Flush sites had greater mean overstory basal area (36 m²/ha, P=0.0001) and greater mean densities of stems in the overstory (480 stems/ha, P=0.0002), sapling (810 stems/ha, P=0.0208), and midstory (4,570 stems/ha, P=0.0376) layers, but the understory was less dense (2,193 stems/ha, P=0.0001) on flush sites than on random sites .
In Nacogdoches County, Texas, wintering American woodcocks occurred in a 2-year-old loblolly-shortleaf pine plantation (2.5 American woodcocks/ha), a pole-sized mixed pine-hardwood stand (1.7/ha), and a sawtimber-sized mixed pine-hardwood stand (0.6/ha) during the day. Use was primarily restricted to depressions or drainages dominated by hardwoods, and use of mature bottomland hardwood stands occurred when an understory of saplings, vines, and forbs was present . In the loblolly-shortleaf pine plantation, American woodcock foraging increased as foliage density of ground-level (0-10 inches (0-25 cm)) vegetation decreased (R²=0.51) and midstory (10.2-29.5 inches (26-75 cm)) vegetation increased (R²=0.41). As the height of dominant woody understory species increased, American woodcock foraging activity increased (R²=0.46). Average height of dominant vegetation was 10.5 feet (3.2 m). The authors surmised that sparse vegetation at ground level likely increased mobility and visibility, and dense vegetation in the midstory increased protection from predators .
Selection for any one vegetation characteristic "probably reveals little about habitat suitability for American woodcocks" . For example, Causey (1989 cited in ) reported high variability in 4 habitat characteristics in American woodcock habitats in Alabama:
|Vegetation characteristics of habitats used by American woodcocks in the Lower Coastal Plain of Alabama (Causey 1989 cited in )|
Canopy cover (%)
Stem density (number/ha)
If stem density is high in the overstory, only a sparse understory may be required, but as stem density decreases in the overstory, a denser understory may be needed to provide suitable cover . Selection for a diversity of cover ranges may also be a result of American woodcocks selecting for different covers under different light conditions. Diurnal flush sites in bottomland hardwood forest in south-central Louisiana had denser understories and more and smaller trees than random sites (P<0.05 for all variables). Selection of dense vegetation increased with light intensity. On relatively bright days, American woodcocks were flushed from areas with thick vegetation such as cane and blackberry thickets and from heavily treed areas. On relatively dark days, they were flushed from more open areas .
During winter, American woodcocks feed more frequently at night (see Diet). Thus, exposed bare ground and litter cover may be relatively less important in diurnal habitats in the South than in the North. In Nacogdoches County, Texas, bare ground cover was low and did not differ between habitat used by wintering American woodcocks during the day (5.1%) and random (5.3%) locations . Litter cover at flush sites was not different from litter cover at random sites in 2 study areas in east-central Alabama; however, litter depth at 1 of the study areas was less at flush sites (1.5 inches (3.8 cm)) than random sites (1.9 inches (4.8 cm), P<0.05) and similar at the other (flush sites: 1.3 inches (3.3 cm); random sites: 1.1 inches (2.9 cm)) . But in another Nacogdoches County study, American woodcock foraging increased as the percent of bare soil increased (R²=0.29) and the percent of litter decreased (R²=0.46, P<0.05 for all variables) . Methodology differences may account for these differences.
Like breeding-range diurnal habitats, diurnal habitats on the wintering range are typically close to an opening. Distances from the midpoint of diurnal activity centers to the nearest opening averaged 213 feet (65 m) in Lee County, Alabama . In east-central Alabama, diurnal habitats used by American woodcocks were generally within 460 feet (140 m) of a large field used at night . Other researchers reported similar findings in Louisiana  and Texas . For more information on this topic, see Movements.
Nocturnal habitats: American woodcocks commonly spend the night in fields and other open areas, although some remain in forests used during the day or move to different forest habitats at night [16,61,79,147]. The proportion of American woodcocks using openings at night varies seasonally and with gender and age. Characteristics of openings used at night vary throughout the American woodcock's range [30,119].
Habitat shifts: During the breeding season, American woodcocks make crepuscular flights to fields at night primarily after courtship activity has ceased . In Massachusetts, they began using fields at night in mid-June. Field use at night peaked in July and declined thereafter, perhaps in response to the physiological stresses of molt that occur at this time, but use of openings continued through to migration in fall . In Penobscot County, Maine, male American woodcocks used old fields as singing grounds at dusk and dawn and did not remain in the fields at night. As courtship activity waned beginning in mid-June, males gradually transitioned to using the fields throughout the night . Frequently, openings used at night during the breeding season are the same as those used during courtship (see Singing grounds) [26,30,85,123,130,179]. In Maine, American woodcocks never roosted in clearcuts that were not also used as singing grounds . Juvenile males may use openings at night more than females and adult males . At the Moosehorn National Wildlife Refuge, juvenile males used open areas at night more often than juvenile females, and adult males used open areas more often than adult females . In Penobscot County, Maine, however, juvenile males (94%) and juvenile females (93%) used open areas equally at night. Molting and nonmolting juveniles apparently used nocturnal habitats similarly .
Habitat structure: The presence of woody vegetation is apparently a key factor determining use of openings at night. At the Moosehorn National Wildlife Refuge, juveniles commonly used old fields (38% of radiolocations), Christmas tree plantations (38%), and pastures (15%) and relatively infrequently used a power line corridor, a highway median, a woods road, bogs, and clearcuts (10%) at night. Old fields had scattered shrub clumps and variable grass cover; the topsoil in some areas had been removed, and juveniles were often found on these areas. In less frequently used pastures, shrubs were sparse and grass cover was higher and more uniformly distributed . In old fields in Penobscot County, Maine, "pockets" of short ground cover surrounded by taller cover were used more frequently at night than unbroken stands of tall, densely growing ground cover . Optimum types and characteristics of openings and forest used at night were not well understood as of this writing (2010) , but are likely similar to those required for use as singing grounds.
Winter nocturnal habitats: Nocturnal habitats of wintering American woodcocks include crop fields [14,19,40,160], hayfields , pastures [7,14,40], burned fields , fallow fields , old fields [7,41], pipeline rights-of-way , clearcuts [14,82], and stream terraces . Many nocturnal habitats on wintering grounds are open areas that "afford no cover protection at all"  such as freshly plowed crop fields . Use of crop fields appears to vary regionally, a difference that presumably reflects the regional variability of agricultural practices and thus the availability of different field types . In some cases crop fields, hayfields, and pastures are less preferred than fallow or old fields [7,82,160]. In Georgia and Virginia, wintering American woodcocks did not use crop fields or pastures at night during the 2-year study period and clearcuts were preferred .
Whether American woodcocks use fields at night may depend on moon phase and temperature. American woodcocks used openings closer to brushy ecotones on bright nights compared to dark nights, and fields with sparse cover tended to be used only on dark nights. On cold, bright nights, individuals made crepuscular flights to fields but appeared less likely to remain in the field than on warm, dark nights. Use of fields at night was influenced by the following factors: season; type and density of cover; soil moisture; temperature; illumination of the sky; distance from daytime cover; and amount of disturbance experienced by individuals in the field . In northeastern Georgia, number of American woodcocks using fields at night decreased significantly as winter progressed and courtship behavior increased (P<0.001) . For more information on this topic, see Movements.
Habitat structure: Use of nocturnal habitats on wintering grounds is in part determined by vegetation structure and field size. In northeastern Georgia, American woodcock use of openings at night varied by opening size and type (1- to 3- year old seed-tree clearcuts, old fields, hayfields, and pastures) (P<0.001). Large (139.9-786.0 acres (56.6-318.1 ha)) and medium-sized (13.6-98.8 acres (5.5-40.0 ha)) openings were used more frequently than small (2.2-13.3 acres (0.9-5.4 ha)) openings (P<0.001), suggesting that American woodcocks required openings >5.4 acres (2.2 ha) in size. The authors suggested that large openings may provide protection from raptors hunting from perch trees. American woodcock densities and use were higher in seed-tree clearcuts (4.6 American woodcocks detected/observer-hr) and old fields (4.2/observer-hr) than hayfields (1.5/observer-hr) and pastures (1.3/observer-hr). The authors suggested that because individuals observed in hayfields and pastures were usually located at brushy field edges, American woodcocks were probably attracted to certain vegetation structures along the edge of the openings rather than to the vegetation in the opening itself. Foliage volume in the 2.6- to 6.6-foot (0.8-2.0 m) layer and percent bare soil explained nearly 80% of the variance in abundance of American woodcocks in seed-tree clearcuts and old fields . In Nacogdoches County, Texas, wintering American woodcocks selected sites—such as burned old fields, stream terraces, and mowed and unmowed fields—that had greater bare soil and density and canopy cover of sapling-sized trees (>0.5 m tall) and less shrub (v<0.5 m tall) cover than random sites for nocturnal use. These authors suggested moderate bare ground was preferred in nocturnal habitats and that too much bare soil coupled with a lack of overhead cover would deter use of sites by wintering American woodcocks .
Habitat used during migration: Patterns of habitat use during migration resemble patterns during the breeding and wintering seasons [26,107,140]. In a review, Myatt and Krementz  surmised that during the "initial leg of migration, woodcock shift from using early successional habitat almost exclusively, which is typical on the breeding grounds, to a wider range of early successional and mature forests, which is typical on the wintering grounds." In addition, American woodcocks occasionally occur in unusual habitats such as on lawns and gardens in rural and urban areas during migration, particularly during adverse weather such as during snowstorms (see Migration) .Cover requirements:
Singing grounds: American woodcock singing grounds are typically open or brushy areas in early succession, with grasses, forbs, and scattered young trees and shrubs [16,38,125,178]. Because the male American woodcock's flight display may reach heights of 300 feet (91 m) or more in the air , openings are used to perform these flights. Singing grounds include crop fields [93,107], pastures [35,70,93,101,107,155], orchards [70,155], blueberry fields , hayfields , old fields (e.g., [35,52,70,85,101,107,111,132,155,179]), meadows [35,70], bogs [70,107], conifer swamps , wetlands [52,107,133], forest tree gaps [35,70], clearcuts and other logged areas [35,69,70,100,107,111,114,132,133,155], pine plantations [52,161], burned areas [9,107,133,155], rock outcroppings [101,107], gravel pits , landfills , power line or pipeline rights-of-way [70,101,155], railroad tracks , trails [70,111], log landings [111,114], roads [35,93,101,107,111,114,132,155], baseball diamonds, lawns, and gardens . At the Moosehorn National Wildlife Refuge, singing males displayed on snow and frozen ponds . Despite the variety indicated here, most studies show substantial use of old fields and young (<10 years old) clearcuts as singing grounds (e.g., [52,100,101,111,114,123,133,155]).
Size: American woodcocks use openings of all sizes as singing grounds. Some researchers define the size of the singing ground as the total size of the clearing, whereas other researchers define the size as the portion of the total clearing used by the individual, sometimes referred to as the "alighting site" [101,171]. Alighting sites may be as small as 25 feet² (2.3 m²) . A male may utilize one or many alighting sites within a singing ground on a given night . Males may use more than one singing ground within the same night and throughout the breeding season [105,107,155]. Openings as small as 100 feet² (9.2 m²) and as large as 100 acres (40.5 ha) are used as singing grounds [16,107,116,155,175,179]. Small openings typically have one displaying male, whereas large openings often have several males displaying at various places simultaneously .
The optimum size of singing grounds was not well known as of this writing (2010). Because American woodcocks are territorial at singing grounds, many small openings may be more desirable than one large opening. In Boone County, Missouri, the density of displaying males declined with increasing field size (R²= -0.535, P=0.010) . Use of singing grounds by males in Centre County, Pennsylvania, was negatively correlated with opening size (P=0.004). Singing grounds with greatest frequency of use were small, perhaps not because of their size but because they often had dense shrubs . In New Brunswick, higher densities of singing males (0.11 singing male/ha) occurred in clearcuts and selection cuts <49 acres (20 ha) in size than on larger cuts (0.05/ha, P<0.001). The authors suggested that small cuts offered more edge and thus more suitable territories per unit area than large cuts . Maxfield  suggested that the "ideal" singing ground was 0.1 acre (0.04 ha), but provided little evidence to support this. In Pennsylvania, 0.25-acre (0.1 ha) clearings appeared "adequate" when surrounded by low vegetation . In Oklahoma, "good" sites for displaying American woodcocks were openings ≥390 feet (120 m) in diameter (about 2.8 acres (1.1 ha)) . Sizes of singing grounds may depend on the amount of woody cover within the opening and the height of surrounding trees .
Habitat structure: Openings with scattered patches of low woody vegetation are important as singing grounds. In Terrebonne County, Quebec, openings without woody vegetation were not frequented by displaying males; 89% of the openings had 4% to 30% canopy cover of woody vegetation >3 feet (0.9 m) tall but ≤8% canopy cover of woody vegetation >15 feet (4.6 m) tall . Occupied singing grounds in Centre County, Pennsylvania, had a mean canopy height of 11.2 feet (3.4 m) . In Boone County, Missouri, American woodcocks displayed in pastures and old fields that had varying densities of shrubs and young trees. Highest densities of singing males occurred in old fields with the highest densities of woody stems. The density of displaying males increased with densities of all deciduous and coniferous stems >1 inch (2.5 cm) DBH and declined with increasing numbers of coniferous stems ≤1 inch DBH and field size (R2=0.83; P=0001) . In northeastern New Brunswick, mean density (1,200 stems/ha) and height (10.2 feet (3.1 m)) of vegetation was lower at display sites than random sites . Use of singing grounds by male American woodcocks in Centre County, Pennsylvania, was positively correlated with shrub density (P<0.0004) .
Some researchers reported that American woodcocks used openings with no or little woody vegetation as singing grounds [89,93,101,107,179]. At Houghton Lake State Forest, singing grounds were located close to aspen edges in openings with grass or bare ground cover but were located throughout the opening when scattered shrubs were present . Wishart and Bider  suggested that fields without shrubs are less preferred and used only when fields with shrubs are limited in number. Some woody cover may be desirable on display grounds to help deter avian predators, particularly because male courtship displays may make displaying males conspicuous to predators (see Life span and survival). However, woody cover that is too dense or too tall may interfere with display flights [51,123,155,179]. Wishart and Bider  found that trees >15 feet (4.6 m) tall never exceeded 8% of the total cover in singing grounds. Marshall  found an old field or a clearcut was not used as a singing ground until woody vegetation began encroaching into the opening, but was not used as a singing ground when woody vegetation >6 feet (1.8 m) tall covered >60% of an opening. For more information on this study, see Succession.
Woody cover may act as a barrier to isolate territorial males, thereby reducing costs associated with aggressive interactions and allowing greater densities of displaying males [93,101,107,111,133,155,180]. Wishart and Bider  noted frequent aggression between territorial males not isolated by a structural barrier. In Pennsylvania, observations suggested that ≥2 male American woodcocks used a large field as a singing ground when the field was broken up by clumps of shrubs or hedgerows . In Penobscot County, Maine, mean distance between singing grounds was 508 feet (155 m), but for those singing grounds that were <600 feet (180 m) apart, 80% were separated by trees, shrubs, or a ridge . Singing grounds were typically >450 feet (140 m) apart in Maine , >490 feet (150 m) apart in Oklahoma , and >650 feet (200 m) apart in Pennsylvania .
The structure of the singing ground and the actual alighting site differ. Usually the alighting site on the singing ground has sparse vegetation above the ground level compared to the surrounding singing ground [70,171]. In Boone County, Missouri, American woodcocks displayed in pastures and old fields with high densities of woody stems but used only a small portion of the fields and selected alighting sites with sparse or low vegetative cover . In Louisiana, pastures of 3- to 5-foot (0.9-1.5 m) tall yankeeweed (Eupatorium compositifolium) with small (25-40 feet (7.6-12.2 m) in diameter) openings for alighting sites seemed to be preferred for singing grounds . Alighting sites with low density and height of plants was also observed in northeastern New Brunswick .
The characteristics of surrounding habitats—particularly the type and height of surrounding trees—may be as important as the characteristics of the singing ground itself [6,149,155]. In the northern lower peninsula of Michigan, clearings bordered by aspen-dominated habitats were used by singing male American woodcocks more often than expected (P<0.05). Aspen presence within the clearing was less important than having aspen bordering the clearing , perhaps because males often select singing grounds close to preferred diurnal habitats such as aspen forest.
Tree heights influenced the use of 50 singing grounds in Massachusetts. Small singing grounds had small surrounding trees and large singing grounds had large surrounding trees :
|Relationship between size of American woodcock singing grounds and height of surrounding trees |
|Size of singing grounds (feet²)||Minimum height of surrounding trees (feet)|
In Centre County, Pennsylvania, frequency of use of singing grounds by male American woodcocks was negatively correlated with opening size (P=0.004) and height of the farthest edge (P=0.0001). Singing grounds with the greatest use had low vegetation at their edges . Selection of small trees surrounding small openings may allow for escape paths from the site [51,155]. Because vegetation scatters sound, males may also be selecting singing grounds based upon structural cues that index sound transmission. Hervieux  found that male American woodcocks selected singing grounds in central New Brunswick where amplitude of the courtship call was maximized, which may help attract females and/or repel rival males. Singing grounds may also be selected based on light intensity, which is affected by vegetation structure. In northeastern New Brunswick, 98-foot (30 m) radius plots were centered at alighting sites. A gradual increase in densities and heights of vegetation occurred from the center of the plot outwards. Stem densities were lowest in the directions of sunrise and sunset, suggesting that selection of an alighting site was influenced by the amount of light that reached the site during dawn and dusk. Selecting alighting sites where light is present for longer periods at dawn and dusk may benefit the male by increasing mating success .
American woodcocks may select singing grounds close to preferred habitats. Several researchers noted the close proximity of singing grounds to diurnal habitats used by both sexes for foraging and by females for nesting and brood rearing [38,101,107,125,155,175,178,179]. Some speculated that the quality of adjacent diurnal habitats may in part determine singing ground use by males [26,35,150,175]. In Huntingdon County, Pennsylvania, American woodcock males selected open areas that were always immediately adjacent to their diurnal cover . Other researchers found that American woodcocks did not always select the closest available singing ground [63,130], and some studies did not determine whether the closest diurnal habitats were actually being used (e.g., ). Ramakka  found that in Penobscot County, Maine, males often did not use the singing ground nearest to their diurnal habitat; although the nearest singing grounds were an average of 558 feet (170 m) away, males flew to singing grounds that were 1,850 feet (564 m) away on average. In Massachusetts, 29% of singing grounds were immediately adjacent to the male's diurnal habitat; 60% were 450 to 600 feet (140-180 m) from the singing ground; and the remaining were >690 feet (210 m) away . Hudgins and others  found that distance moved between courtship-period and nocturnal locations varied considerably. Mean distances between singing grounds and diurnal habitats ranged from 118 feet (36 m)  to 1,850 feet (564 m) .
Nests: The female American woodcock constructs an open nest on the ground by shaping a shallow depression into litter [70,107,155,178]. She typically builds her nest close to the male's singing ground [46,52,107,155,178] and close to feeding areas [46,171]. Nests may be in wet or dry sites [16,26], but the nest bowl is usually positioned in a well-drained site such as on a small hummock [45,107,171] that is free of snow . Nests are often located <3 feet (1 m) from the base of a tree or shrub, beside a log or stump, or within fallen brush [21,46,70,107,144,155,178]. Most nests are concealed by vegetation. In a study of 32 nests in northern Wisconsin, Gregg and Hale  reported that 69% were under a conifer bough, in a shrub clump, in herbaceous cover, or at the base of a deciduous tree, while 31% were not concealed. At the Moosehorn National Wildlife Refuge, females avoided areas with dense conifer understories, but nests were often located under or near one of the few scattered spruce or fir saplings available . Sometimes a nest may be unconcealed when first constructed but concealed by vegetation at hatching time .
Habitat use: American woodcocks nest in forests, shrublands, openings, and their ecotones (e.g., [12,21,21,46,52,70,93,107,111,123]). Early-successional hardwood or mixed hardwood-conifer forests appear to be particularly important for nesting American woodcocks, but conifer forests and openings are also used [12,31,71,93,106,107,111,144,171,178]. In Alabama, nests were in mixed pine-hardwood forests (61%), hardwood forests (17%), pine forests (13%), and open areas (9%) . Nests occurred in shrubby old fields (57%), at forest-old field ecotones (37%), and in forests (7%) in Missouri . In Pennsylvania, nests occurred commonly on the edges of small tree or shrub thickets where vegetation was 12 feet (3.7 m) tall on average, but also in old fields, young mixed-hardwood stands 50 feet (15.2 m) tall, and bottomlands adjacent to small streams . In Carlton County, Minnesota, nesting females used mixed-hardwood, lowland conifer, upland conifer, aspen, and birch forests, roads, and openings in proportion their availability . In Wisconsin, most (91%) American woodcock nests were in aspen/alder stands. Northern hardwood and conifer forests were infrequently used, which was attributed to greater shrub cover in aspen/alder forest compared to other forest types . Weeden  found that most nests (70%) were associated with overstories dominated by alder and birch <25 feet (7.6 m) tall. Conifers made up a small portion (<20%) of these sites but were an important component of the habitats . In Maine, nesting American woodcocks preferred young birch-aspen-spruce-fir forest (47%) but also nested in alder or alder-willow habitat (26%), birch-aspen and birch-aspen-maple forest (21%), cleared land (5%), and brushland (4%) . Another study in Maine found that nests were located in aspen, tamarack, and speckled alder habitats more often than expected based upon availability at random sites (P<0.001). Nests were more likely to be in forests with deciduous shrub (e.g., beaked hazelnut and alder) understories and less likely to be in forests with understories of spruce or fir or at sites with no understory (P<0.001) .
American woodcocks often select moist lowland sites for nesting, but dry upland sites are also used [12,31,71,93,107,111,171,178]. In Alabama, more nests were found in lowland (79%) sites compared to upland (21%) sites . In Maine, more nests were located in moist slopes and lowlands (62%) than dry slopes and uplands (39%). The authors noted that some habitats in this study, particularly alder-willow habitats, were too wet in spring for early-nesting individuals . In Carlton County, Minnesota, nesting females used upland and lowland sites in proportion to their availability . At the Moosehorn National Wildlife Refuge, preference for aspen habitat was attributed to the availability of well-drained soils in spring . Nests in Boone County, Missouri, were usually in dry upland sites , as were nests in Pennsylvania  and the northern lower peninsula of Michigan , but nests in Alabama were usually on flat bottomlands near water .
Habitat structure: The structure of the understory appears to be the most important feature of American woodcock nesting habitat. Typically, mean canopy height is low, mean number of trees >3.0 inches (7.6 cm) DBH and basal area are low, and mean density of saplings <3 inches DBH and shrubs are high at nest sites .
|A review of mean habitat characteristics at American woodcock nest sites in 5 states (compiled by )|
|Trees >7.6 cm
|Saplings <7.6 cm
|Distance to nearest stem
|*Data not available.|
|**Trees and saplings combined.|
|***Includes subdominant trees.|
|****Includes seedlings and shrubs >1 m.|
|*****All woody stems <2.5 cm DBH.|
|******Includes seedlings, saplings, and vines.|
In Madison and Nicholas counties, Kentucky, mean canopy height, number of shrub stems, number of all trees, and number of sapling trees (1-6 inch (2.5-15.2 cm) DBH) were significantly greater at nest sites than random sites (P<0.004 for all variables) . In the northern lower peninsula of Michigan, nest sites had moderate ground (39%) and understory (43%) cover .
Choice of nest sites varies between first nests and renests. Most females nest before vegetation green-up but may renest after new plant growth is present [45,106]. At the Moosehorn National Wildlife Refuge, sites around first nests had 50% less basal area of dead trees (P=0.05) and twice as many stems of aspen (P=0.03), cherry (P=0.001), and viburnum (Viburnum spp., P=0.05) than random sites, while renest sites had taller trees than random sites (P=0.02). Forty-nine percent of first nests were in clearcuts ≤10 years old, whereas 25% of renests were in these areas. The authors suggested that in early spring before green-up, clearcuts of sprouting species may provide the necessary stem density and cover for nesting individuals. During renesting, clearcuts remained important, but leaves and forbs appeared to allow use of sites with fewer woody stems and habitats in a wider range of successional stages .
American woodcocks may move substantial distances from the first nest to renest. At the Moosehorn National Wildlife Refuge, females that abandoned nests or had nests destroyed by predators moved an average of 4.2 miles (6.7 km) to renest; in contrast, females that lost broods moved only 0.4 miles (0.6 km) to renest, a significant difference (P=0.10). This suggests that nesting-area fidelity was influenced more by successfully hatching a clutch than by successfully rearing a brood [103,104].
Many researchers reported that American woodcock nests were located close to ecotones of forests and openings [9,21,45,46,111]. In Pennsylvania, 95% of American woodcock nests were within 70 feet (20 m) of an edge . In northern Wisconsin, 75% of nests were within 45 feet (14 m) of an edge . In northern Wisconsin, most nests in aspen and alder forests were located near (<30 feet (9 m)) the brushy edge of "poorly stocked" poletimber stands . Examination of 89 American woodcock nests at the Moosehorn National Wildlife Refuge found that 44% of nests were located in or on the edge (<36 feet (11 m)) of a young (≤10 years old) clearcut . In Missouri, nests were most commonly in old fields and old field-forest edges, and nests located in forests were always within 70 feet (20 m) of an opening . Additional studies show a similar pattern:
|Review of distance of American woodcock nests to the nearest opening|
|Location||Distance to nearest opening (m)|
|New York||16.6 (Chambers 1976 cited in )|
|New York||8.7 |
|Portage County, Wisconsin||6 |
Because edge vegetation tends to be brushy, the tendency of nests to be located close to habitat edges may reflect a preference for dense woody vegetation . Affinity to edge habitats may also reflect a preference for close proximity to singing grounds . Most female American woodcocks nest close (<660 feet (200 m)) to a singing ground:
|Mean distances between nests and nearest singing grounds|
|Location||Mean distance (m)|
|Penobscot County, Maine||69 |
|Central Massachusetts||94 |
|Centre County, Pennsylvania||162 |
|Carlton County, Minnesota||122 |
|Northern Wisconsin||119 |
|Portage County, Wisconsin||121 |
Females typically visit more than one singing ground [171,173]. As of this writing (2010), it was unclear whether females mate with the displaying male in the nearest singing ground. In Carlton County, Minnesota, American woodcock females visited 1 to 4 singing grounds. Distance from the nest to the nearest singing ground was about 400 feet (120 m), but distance to the singing ground on which the female was originally captured was about 2,000 feet (610 m) .
Distribution: Nests are typically not clumped, although concentrations of nests are occasionally observed [52,107]. Coon and others  found that nest distribution was random each year of a 3-year study (P>0.05). In Wisconsin, nest density ranged from 0.04 nest/acre to 0.33 nest/acre . Mendall and Aldous  observed nest concentrations when snow cover restricted available nesting habitat. Suggested reasons for nest concentrations included: nesting females are not territorial and concentrate in the best habitats; snow cover restricts nest site availability; or nesting females select the edges of their home ranges .
Weather: Habitat used by nesting females may vary among years, depending upon the amount and extent of snow cover and frost-free soil. When snow is present during nesting, females may have to nest on available snow-free sites rather than on "optimum" sites . At the Moosehorn National Wildlife Refuge the habitat around nest sites did not differ among 3 years although snow depth, precipitation, and snowmelt patterns differed among years . It is unclear whether weather affects nest site selection, but it apparently affects nest mortality (see Life span and survival).
Broods: American woodcock young are precocial and within 2 days, hatchlings may be found over 300 feet (90 m) from their natal nest. In the Northeast, young American woodcocks were found at steadily increasing distances from their nest (29-542 feet (9-165 m)) until they were about a week old; thereafter, distance decreased slightly (351-390 feet (107-119 m)) until young were 14 to 15 days old and able to take short flights . At this time, young are about half of adult size . At 18 days of age, young American woodcocks are capable of sustained flight [46,70,178]. By 30 days, young are about adult size, strong flyers [70,155], and can be found 570 feet (174 m) from their natal nests . The movements of broods may encompass large areas. In northern Wisconsin, a brood followed from 6 days old to 32 days old occupied an area of 11 acres (4.5 ha) . The area utilized by three 24- to 26-day-old broods ranged from 15.1 to 16.5 acres (6.1-6.7 ha) in Carlton County, Minnesota .
Brood habitat use varies as broods mature and become increasingly mobile. Initially, nest and brood habitats are similar because females do not move young broods far from the nest . However, as broods mature, they travel greater distances from the nest and use denser forests with wetter soils than those at nest sites and/or hatching areas [16,70]. In the northern lower peninsula of Michigan, nests and broods were found in similar habitats: aspen (nests: 63%, broods: 47%); alder (nests: 13%, broods: 16%); clearings in aspen forest (nests: 19%, broods: 0%); conifer swamps (nests: 6%, broods: 11%); and mixed-hardwood forest (nest: 0%, broods: 26%). However, nest and brood sites differed in habitat structure, with broods occurring at damp sites nearer to standing water with shorter ground cover and greater basal area and density of intermediate-sized (20-29 feet (6.1-8.8 m) tall) trees (P<0.05 for all variables) . In Carlton County, Minnesota, preferred habitats had moderate shrub density (15,000-25,000 stems/acre) and sparser herb cover than what was randomly available .
Several researchers reported that broods were often found in poorly drained areas [12,155,173]. Wenstrom  reported that broods were found close to standing water and relatively farther from openings than were nests. In Boone County, Missouri, on average, broods were in areas with greater canopy closure and basal area of trees, deeper litter, and greater soil moisture than nest sites (P<0.05 for all variables) . In Oswego County, New York, brood sites differed from random sites by having greater vegetative cover, greater earthworm densities, and denser overstory vegetation . In northeastern Minnesota, brooding female American woodcocks were positively associated with upland sites. After brood break-up, juveniles and adult females shifted from upland sites to lowland sites coincident with a general decrease in soil moisture across habitats. The author suggested that lowland sites too moist for nesting in spring became suitable while upland sites suitable in spring became desiccated and earthworm numbers declined . At the Moosehorn National Wildlife Refuge, 7 young American woodcock broods (<10 days old) occurred in hardwood forest with open to moderate-density ground vegetation and intermediate drainage, and 4 young broods occurred in lowland alder forest with moderate-density ground vegetation .
Habitat shifts may occur during the first 1 to 2 weeks of age, when chicks increase mobility and can take short flights. Although all broods were associated with gray birch and aspen forest with some conifer component at the Moosehorn National
Wildlife Refuge, old broods (>5 days old) preferred more open forests with larger numbers of intermediate-sized trees (9-15 inches (22.9-38.1 cm) DBH; P<0.10) and fewer small trees (3-6 inches (7.6-15.2 cm) DBH; P<0.01) than
young broods (≤5 days old) . In Boone County, Missouri, most nests (57%) occurred in old fields, and the remaining occurred in forest or edge sites, whereas 21% of broods were observed in old fields, and 79%
of broods occurred in forest or edge sites. This suggests that broods shifted from old fields to forests within 2 weeks after hatching . Other studies report apparent brood habitat shifts away from nest sites in openings. In the northern lower peninsula of Michigan, 19% of nests were in openings in aspen forests, but no broods were found in openings . A similar observation was made in Oswego County, New York
Another habitat shift may occur at about the time that broods break up, when young are about 4 to 5 weeks of age, nearly full size, and capable of sustained flight [12,46,70,85,107,173,175]. In Portage County, Wisconsin, flightless broods were generally found in nesting habitat, while flying broods typically used different habitats adjacent to nesting habitat .
Although young broods often avoid openings, at or just prior to brood break-up, young begin to use openings regularly at night and continue to use openings at night until migration [85,175]. Although young shift habitats at brood break-up, most movements made during the 1st week or 2 following brood break-up are short, and most individuals remain in the "same general area" where they hatched [46,70,79]. Premigratory dispersal occurs occasionally (see Migration).
|An American woodcock at the Eastern Neck National Wildlife Refuge, Maryland. US Fish and Wildlife Service Photo.|
In addition to earthworms, beetles (Coleoptera), millipedes (Diplopoda), centipedes (Chilopoda), moths and butterflies (Lepidoptera), ants (Formicidae), flies (Diptera), spiders (Araneae), locusts (Orthoptera), and other invertebrates are also eaten [14,70,107,178]. Vegetable matter, usually small seeds and fruit of plants such as smartweed (Polygonum spp.), blackberry, grasses, and sedges, occur frequently in the diet at low volume [70,107,178]. Grit is also consumed . American woodcocks drink water , but most water requirements are likely met with food [16,70,107]. Some notable exceptions in types of invertebrates and plants consumed are reviewed by Keppie and Whiting .
The American woodcock's diet is similar across age and gender classes [46,70,107] and across the species' geographic range , although species of invertebrates and plants consumed varies by location, season, and year, depending upon availability [109,135,168]. Despite the overwhelming importance of earthworms in the diet, American woodcocks are considered "opportunistic feeders" [14,114,155] and often consume earthworms according to their abundance [114,123]. In New Brunswick, earthworms occurred in 91% of American woodcock stomachs collected in alder habitats and 40% of stomachs of individuals collected from clearcut and selection-cut sites, whereas insects (e.g., beetle larvae, butterfly and moth larvae and pupae, and fly larvae) occurred in 73% and 100% of American woodcock stomachs in alder and cut sites, respectively. This suggests that American woodcocks consume other soil invertebrates more extensively when earthworms are less available . Sperry (1940 cited in ) examined the stomach contents of American woodcocks collected from March through December throughout the species' range and found that the percentage of earthworms in the diet varied by month. Earthworms were lowest in the diet in December (48.2%), September (51.9%), and August (55.9%). More insects, especially flies, were taken in August than in any other month (38.3%), and in September, 27.8% of foods taken were seeds (Sperry 1940 cited in ). Dry soils during August and September may make earthworms difficult to obtain, causing American woodcocks to consume other types of invertebrates . For more information on this topic, see Weather.
Feeding activity: American woodcocks feed during the day and at night throughout their range, often concentrating movements and feeding activities at dusk and/or dawn [14,40,119]. In spring and summer, American woodcocks typically feed more during the day than at night, whereas more individuals feed nocturnally during migration and in winter [16,30,40,70,84,86,113,119,132,180]. Based on the absence of earthworms in some habitats used by migratory American woodcock during the day, American woodcocks shift from more diurnal to more nocturnal feeding during migration . Weather affects feeding activity. In Louisiana, American woodcocks typically fed at night but fed during the day during cold weather when the ground froze at night and thawed during the day .
Young chicks rely upon the mother for food for about 1 week. They may begin eating as soon as the yolk is resorbed [46,155,173]. The female continues to feed her chicks after they begin obtaining food on their own . Females with broods occasionally leave the chicks at dusk to feed in separate or nearby habitats. Females with broods at the Moosehorn National Wildlife Refuge frequently (37% of observations) left their broods during crepuscular periods to forage .
Forage-site selection: Most studies examining American woodcock habitat use rely exclusively on information on the abundance and biomass of earthworms at a location and do not consider availability of other soil invertebrates, although they may be a substantial portion of the American woodcock's diet . Cade  assumed that suitable soil texture and drainage characteristics for earthworms were likely suitable for other soil invertebrates consumed by American woodcocks. As of this writing (2010), few studies examined nonearthworm invertebrates in American woodcock habitat-use studies; therefore, this review focuses on the effects of earthworm availability on American woodcock habitat use.
Many studies suggested that American woodcocks select habitats based on earthworm abundance [13,29,63,70,93,123,137]. At Houghton Lake State Forest, the number of broods using forest-field complexes in aspen habitat was significantly correlated with earthworm abundance during 2 years of the study (r=0.35, P<0.01 for both years) . In young 2nd-growth alder and aspen forest in central Maine, the degree to which American woodcocks used diurnal habitats appeared directly related to the abundance of Lumbricid earthworms, with heavily used sites having higher abundance and biomass of earthworms than rarely used sites (P<0.01 for all variables) . In Piscataquis and Hancock counties in Maine, diurnal flush sites had significantly greater earthworm biomass than randomly selected sites within the same habitat (P<0.05) except within alder habitats, which had relatively uniform distribution of earthworms at used and random sites . In Carlton County, Minnesota, diurnal "high-use" areas were identified for juvenile females for a 5-month period (April-October), and earthworm biomass in those areas was compared to nearby random areas. In 7 of 10 comparisons, earthworm biomass was significantly greater in high-use areas than random areas . In Centre County, Pennsylvania, microsites used by adult males during the day had higher earthworm biomass than random sites . Wintering American woodcock in Hyde County, North Carolina, foraged preferentially in cutover soybean (Glycine max) fields compared to disced corn and common wheat fields . Availability of earthworms among fields was similar (P>0.05), but percent protein of earthworms found in soybean fields was significantly greater than in other field types (P<0.05). Within soybean fields, American woodcock selected microforaging sites that had greater earthworm biomass than nearby random sites (P<0.05), suggesting that American woodcocks may select habitat based upon quality and/or quantity of earthworms .
However, there are many cases where earthworm abundance and/or biomass was either not related to American woodcock habitat use or where other habitat attributes, such as soil characteristics or stand structure, were more important to American woodcocks than prey abundance [11,46,67,87,93,108,137,147,155,179]. In Nacogdoches County, Texas, average soil moisture was positively related to American woodcock foraging activity (R²=0.34; P<0.05). Increased soil moisture appeared to enhance American woodcock's ability to probe for food in the soil. However, higher correlation coefficients for vegetation variables suggested that vegetation characteristics were relatively more important in influencing American woodcock foraging activities than soil characteristics . For more information, see Winter diurnal habitats. A review stated that there is a correlation between American woodcock occurrence and earthworm abundance only if other requirements of American woodcock habitat—such as light intensity, ground cover, vegetational structure or the proximity of the site to some other habitat feature—are met .
Optimum earthworm abundance and biomass for American woodcocks were not well known as of this writing (2010), partly because differences in methodology make comparisons among studies difficult . At the Moosehorn National Wildlife Refuge, Reynolds and others  reported that sites rarely used by American woodcocks had average earthworm biomass of 7.8 g/m², commonly used sites had 15.4 g/m², and heavily used sites had 18.2 g/m². The authors sampled sites >1 year after they were used. Other Maine studies reported earthworm biomass at foraging sites ranging from 8.4 g/m² to 8.9 g/m² [114,147]. Cade  determined that suitability levels for mean earthworm densities are optimal for American woodcocks when ≥56 earthworms/m² are available, decreasing to unsuitable when ≤16 earthworms/m² are available. Parris  found that habitats used by American woodcocks usually had >30 earthworms/m², whereas stands not used by American woodcocks usually had <15 earthworms/m². The author suggested that most forest and shrub stands with earthworm densities above 30-40 earthworms/m² were likely suitable to American woodcock . Studies in the Northeast documented earthworm densities at American woodcock sites above 30 earthworms/m² (range: 34.4-98.0 earthworms/m²); sites not used by American woodcock or random sites typically had <30 earthworms/m² (range 5.2-24.0 earthworms/m²) [63,93,107,108,123,137,179].
Earthworm availability: Many ecological factors affect earthworm population densities, biomass, and species richness and composition, and thus American woodcock habitat use. Because respiration takes place by diffusion of water-dissolved gases through the body wall, earthworms are particularly affected by soil moisture, temperature, and pH. Each of these factors individually may limit earthworm availability . Other soil characteristics such as soil texture, depth, color, organic matter, and mineral content can interact with soil moisture, temperature, and pH and influence soil conditions for earthworms (, Edwards and Lofty 1977 cited in ). Earthworms consumed by American woodcocks feed primarily on dead and decaying plants. Because of their limited mobility, they live near their food sources. Thus, earthworm abundance and biomass are influenced by food supply and thus by habitat characteristics such as vegetation composition and abundance. Furthermore, habitat characteristics such as vegetation composition and structure may influence earthworm abundance and distribution via their effects on soil moisture, temperature, and pH .
Soil moisture and temperature: Moist soils are an important component of American woodcock habitat because they ensure that earthworms are at or near the soil surface and available to foraging American woodcocks [26,46]. The effect of soil moisture and temperature on earthworms varies within and among earthworm species (Murchie 1954 cited in ). Soils with moisture of 15% to 80% and temperatures of 50 °F to 64 °F (10-18 °C) were optimal for activity of 9 earthworm species in American woodcock breeding habitats in central Maine . Reynolds and Jordan  reported that optimum temperatures for the development of 4 Lumbricid earthworms in Ontario varied by species and ranged from 54 °F to 64°F (12-18 °C). Galbriath (1984 cited in ) reported that soil moistures from 15% to 85% were optimal for earthworms in American woodcock breeding habitats. A review states that surface soil moistures from 20% and 50% appear best for earthworms and American woodcocks .
When soil moisture or temperature temporarily become unsuitable for earthworms, earthworms either aestivate in a mucous cocoon or migrate deeper into the soil profile where more suitable soil conditions exist (Edwards and Lofty 1977 cited in ); either action makes them unavailable to American woodcocks . Soil temperature and moisture vary daily and seasonally; thus, availability of earthworms to American woodcocks also changes .
Slope, aspect, elevation, and physiographic position (bottomland, terrace, and upland) affect soil moisture and temperature, and thus earthworm species richness and abundance. Because darker soils absorb and conduct more incoming solar radiation, soil color influences soil temperature. The parent material and amount of organic matter coming from vegetation influence soil color. In addition, the greater the organic matter content in the soil, the greater its water-holding capacity . Very high and very low amounts of organic matter appear to be deleterious to earthworms (Olson 1928 cited in ).
Soil pH: The optimal pH range for most temperate earthworms is 5.0 to 7.4 (Curry 1998 cited in ). Earthworm density is lower in soils with lower pH values (Ensminger 1954 cited in ). Soil pH was the best single predictor of earthworm biomass in previously farmed spruce-fir, beech-maple-birch, and aspen-birch forests in Maine, with lower pH corresponding to lower mean earthworm biomass . In pine plantations in eastern Texas, pH was positively related to American woodcock foraging activity (R²=0.23), likely due to greater abundance of earthworms in soils with high pH values . However, several studies found that soil pH did not differ between sites used by American woodcock and random sites [8,41,179]. The effect of soil pH on earthworms is reviewed by Owen and Galbraith .
Soil texture: Soil moisture and texture interact to determine soil moisture tensions, which affect abundance of active earthworms [16,136]. In general, well-drained loam soils have optimal soil moisture tension for earthworms and thus provide the greatest abundance of earthworms for foraging American woodcocks . In Maine, moderately well-drained loams and fine sandy loams maintained greater biomass of earthworms throughout summer than other soil types (Galbraith 1984 cited in ). On previously farmed sites in central and eastern Maine, moderately drained fine sandy loams had highest earthworm biomass, followed by well-drained sandy loams and poorly drained silt loams . In 4 counties in southern and eastern Maine, 6 earthworm species preferred loams over clay or sand soils . Similar results were found by Reynolds and Jordan . In central Pennsylvania, earthworms were more abundant in sandy loam soils than in clay or silt soils, but American woodcocks did not forage preferentially in any soil type . Conversely, captive American woodcocks preferentially probed for earthworms in loam and sandy loam and avoided clay loam and sand (P<0.001) .
Extremes in soil drainage appear detrimental to both earthworm and American woodcock occurrence [93,108,173]. Because earthworms have greater tolerance for high than low moisture levels, excessively drained soils reduce suitability to a greater extent than poorly drained soils. Thus, poorly drained loamy sand, silt, sandy clay, and silty clay soils may have greater suitability than their well-drained counterparts, because the higher moisture levels partially compensate for the suboptimal texture . Murchie (1954 cited in ) found that earthworm abundance decreased where sand content rose above 80%, but that high percentages of sand (>75%) were often compensated for by "good" moisture and an accumulation of litter. Thus, soil textures used by earthworms, and consequently American woodcocks, vary regionally, locally, and seasonally as soil moisture changes due to weather .
Earthworm habitat characteristics: Earthworm numbers and biomass are influenced by general habitat characteristics such as plant species composition and groundlayer, understory, and overstory cover [16,117,137]. Earthworms are more abundant in forests where leaves of overstory species are highly palatable, whereas stands composed of overstory species with leaves of low palatability have few or no earthworms (e.g., [16,93,108,115,123]). Alder, aspen and other hardwood leaves are highly palatable to earthworms. Conifer needles are least preferred [70,123,135,137]. Parris  determined leaf palatability of shrubs and trees to 7 earthworm species in American woodcock habitats in Oswego County, New York, and found high palatability of arrowwood, red-osier dogwood, nannyberry (Viburnum lentago), brambles, serviceberry (Amelanchier spp.), hawthorn, speckled alder, pin cherry, eastern hophornbeam (Ostrya virginiana), American hornbeam (Carpinus caroliniana), quaking aspen, basswood, apple, white ash, and yellow birch; and low palatability of sugar maple, black cherry, red maple, American beech, and northern red oak. No conifers were studied, but the author assumed that conifers would have low palatability to earthworms . In addition to being potentially less palatable, conifers tend to acidify the soil, so earthworms decline .
Historical land use: Historically, earthworms may have been absent from large portions of the United States and Canada that are today considered critical American woodcock breeding grounds. Gates (1961 cited in ) stated that the 22 species of earthworms found in Maine are nonnative and were introduced by European colonists in the 17th and 18th centuries; prior to this, there were no earthworms in Maine due to glaciation occurring 10,000 years ago. In Louisiana, 42% of earthworms found were native, and the remaining were nonnative Eurasian species (Herman 1952 cited in ). American woodcocks may have expanded to parts of their current northern breeding grounds after the arrival of European colonists, or they may have eaten other types of food in these areas before nonnative earthworms were introduced .
Earthworm distribution and abundance are partially influenced by historical patterns of agriculture [16,115,137]. Whether a site had been farmed historically was a significant factor determining the abundance of earthworms in 4 counties in central and eastern Maine (P<0.05) . Studies in New Brunswick and Maine found highest earthworm biomass and highest densities of singing males in alder habitat on old farmlands and lower earthworm biomass on areas with no farming history . In central and eastern Maine, earthworms were most abundant at previously farmed sites with moderately drained loamy soil, regardless of forest overstory, suggesting that most previously farmed sites with moderately drained soils could be managed for American woodcock foraging habitat regardless of cover type (see Management Considerations). Historical agricultural practices may have aided establishment of earthworm populations at these sites by increasing organic matter, reducing acidity, and improving moisture retention of the soil .
Weather: Factors affecting earthworm abundance and distribution, such as soil moisture and temperature, vary daily, seasonally, and regionally with respect to weather (e.g., cloud cover, relative humidity, and wind); thus, American woodcock diet and habitat use also vary with weather [39,70,115,117,135,137].
American woodcocks may respond to adverse weather by altering their diet. Diet breadth may increase in early spring due to soil frost. Many earthworm species migrate below the depth of frost and are not available until after frost melts (Edwards and Lofty 1977 cited in ). Winters with limited snowfall can be detrimental to American woodcocks because frost penetrates deep into the soil and may limit availability of earthworms late into spring . McAuley and others  estimated survival of adult male American woodcocks at the Moosehorn National Wildlife Refuge during the breeding period (1 April-15 June) for 3 consecutive years. Survival was positively correlated with mean snow depth in December (P<0.038), negatively correlated with mean snow depth in April (P<0.046), and positively correlated with minimum temperature in December (P<0.054). This suggests that a lack of snow coupled with low temperatures during the previous winter may result in deep frost and reduce invertebrate availability, and that an abundance of snow the previous spring may extend the time earthworms remain unavailable . Earthworms collected from 30 April to 8 September in young alder and aspen forests in central Maine indicated that Lumbricid earthworm number and biomass were lowest in late April and August relative to other months (P<0.01), possibly because of low temperatures in April and low soil moisture in August .
Weather may affect American woodcock movements via its effect on earthworm abundance. Females were more likely to make long-distance movements (>1,600 feet (500 m)) and risk foraging in new areas when environmental conditions were unfavorable, such as when earthworm abundance was low, or when metabolic demands decreased at high temperatures . However, weather may have little or no affect on American woodcocks unless it is particularly severe. In central Pennsylvania during a summer with above-average precipitation, earthworm abundance was consistent across habitats from April through October, and there was no correlation between earthworm abundance and American woodcock use of sites. At the Moosehorn National Wildlife Refuge during a period of average precipitation, earthworm biomass did not differ among forest types, size classes of forests, or understory shrub densities. There was no relationship between earthworm abundance and American woodcock use of sites, and no shifts in habitat use occurred during the breeding season . In Terrebonne County, Quebec, American woodcock habitat shifts were apparently unrelated to soil moisture or earthworm abundance. Earthworm biomass and numbers did not change significantly across seasons or habitats, and all habitats remained relatively damp due to above-average rainfall from June and November . Cumulatively, these studies suggest that during the breeding season, adequate numbers of earthworms may be available to support American woodcocks in a variety of habitats during periods of average or above precipitation [108,147], but that during drought earthworm abundance may limit the number of preferred American woodcock habitats. On wintering grounds, flooding appears to be more of an issue than drought (see Diurnal habitats).MANAGEMENT CONSIDERATIONS:
Changes in land use: Changes in agricultural and forestry practices since European settlement that negatively impacted American woodcocks include fire exclusion and farm abandonment. Historically, Native Americans and early European settlers used fire to create openings dominated by herbaceous vegetation to facilitate hunting and convert forest to pastures or crop fields . These practices likely benefited American woodcocks by creating early-successional forests and openings. Beginning in the early 1900s, large-scale farm abandonment and fire exclusion substantially altered eastern forest structure [15,163,165]. Initially, American woodcock habitat increased, and populations grew as abandoned farmlands grew back into shrublands and young forests. American woodcock populations probably peaked around the 1940s and 1950s, coincident with a peak in the area covered by early-successional habitats. Since the 1950s, however, abandoned farmlands have succeeded to mature forests, and the area of early-successional habitats has declined. The area covered by early-successional forest in the Northeast as of 1999 may be below presettlement levels (Litvaitis and others 1999 cited in ). As of 2001, the proportion of young forest area was smallest in the northeastern (16%) region of the United States, followed by the north-central (24%) and southern (29%) regions . However, in the North-central region, logging and extensive forest fires since the 1970s may have created conditions that are more favorable for American woodcock than those that existed prior to European settlement [3,178].
Increases in urbanization and industrialization have contributed to American woodcock population decline, particularly in the North [28,33,50,63,70]. Dwyer and others  found that numbers of courting males were positively related to old fields (P<0.001) and alder habitat (P<0.001) and negatively related to urban and/or industrial areas (P<0.10) in 9 northeastern states. Thogmartin and others  developed a model to predict abundance of displaying male American woodcocks throughout 18 states in American woodcock's northern breeding range and found that American woodcock counts were highest in landscapes with abundant forests, especially quaking aspen and birch forests, and in locations where forests, shrublands, and grasslands were highly intermixed. Counts were lowest in landscapes with a high degree of human development . In Pennsylvania, the number of courting males declined over time as the amount of area in pasture, sapling-seedling forest, and nonstocked forest (lands that are <10% stocked with live trees) declined and sawtimber forest and urban areas increased .
Draining bottomland hardwood and swampy areas also degrade habitat for American woodcocks . As of 1994, <50% of the area once in bottomland hardwood forest remains; the reduction was primarily a result of conversion to agricultural uses [15,28,33,59]. These impacts may limit American woodcock recruitment and population densities .
Succession: Because American woodcock abundance is closely tied to the abundance of early-successional habitats, succession is considered a major cause of American woodcock habitat loss [46,167]. In general, openings such as clearcuts, old fields, and fallow agricultural fields provide nocturnal cover within the first 3 years, and as vegetation advances through early succession, these areas begin to provide diurnal cover [26,40]. Diurnal cover is provided through the stem exclusion stage and peaks when the seedling-sapling tree canopy begins to close and ground cover declines but understory cover remains high . As canopy height increases and tree canopy continues to close, understory shrubs become sparse, typically during midsuccession, and American woodcock use of the habitat is reduced. As the stand progresses through midsuccession into late succession, however, the quality of the habitat may improve when the understory increases as trees mature and die and the canopy breaks up [26,46].
The length of time a forest provides habitat for American woodcocks depends upon site factors such as soil characteristics, weather, and the type of disturbance . Old fields are typically invaded by woody vegetation from surrounding landscapes; it typically takes much longer for an old field to be reoccupied by trees than for a clearcut . In New Jersey, Krohn and others  described American woodcock's use of old fields through succession: "During the first year following agricultural abandonment, fields supported a dense cover of grass and were little used by American woodcock. After 2 or 3 years, the cover became heterogeneous and eventually woody plants invaded the field. Small openings developed in the ground cover as succession progressed, and woodcock usage generally increased" . In Carleton County, Minnesota, American woodcocks did not use farmlands as singing grounds immediately after abandonment, but used them once shrubs invaded the grassy cover. American woodcocks continued to use farmlands for about 15 to 20 years after abandonment . In Louisiana, fallow fields advanced from nighttime feeding sites with abundant blackberry to suitable daytime cover with dense hardwood thickets in 5 years . In northern Wisconsin, American woodcock used aspen forests "immediately" after clearcutting when the cutting was done within 4,900 feet (1,500 m) of nesting and diurnal roosting cover—in this case, usually stream bottoms overgrown with alder . Clearcuts in upland aspen and conifer forests were used as singing grounds from about 2 to 10 years after cutting; initially, vegetation was too sparse and open, and after 10 years vegetation was too tall and dense . In northeastern Georgia, American woodcocks frequently used 1- to 3-year-old seed-tree clearcuts at night but used >3-year-old clearcuts infrequently . In northern hardwood forests, woody-stem density typically peaks about 5 years after clearcutting, but in central hardwood forests, woody-stem density peaks from 15 to 20 years after clearcutting .
Where tree growth is slower, American woodcocks use habitats for longer periods . In northern Wisconsin, American woodcocks in summer and early fall spent proportionately more time on average in aspen forest than any other forest type, but tended to use young (<10 years old) aspen stands with an alder understory and upland-lowland ecotones more frequently than old (>10 years old) aspen stands . In Terrebonne County, Quebec, average age of alder forests with American woodcocks was 16 years [179,180]. American woodcocks apparently used an opening in aspen forest for 25 years where growth of aspen was slowed by high water tables in Isabella County, Michigan . In northeastern New Brunswick, male American woodcocks displayed at conifer sites 2 to >55 years after disturbance . In central New Brunswick, displaying males occurred in an open area created by fire 18 years prior to the study as well as in 4- to 19-year-old conifer clearcuts . In Centre County, Pennsylvania, mixed-hardwood forest succession over 30 years was sufficient to convert suitable habitat into an unsuitable stage [71,72,93]. Other researchers working in a variety of habitats found males displaying in stands up to 40 years old [151,155,175]. For more information, see Silviculture.
Habitat management: Suitable habitat structure for American woodcocks is often found in early-successional habitats; thus, many of the management recommendations for American woodcock focus on creating and maintaining early-successional habitats. However, American woodcocks may use habitats in all seral stages as long as moderately dense understories and sparse ground cover exist. This led Berry  to suggest that "woodcock habitat can be created and maintained in almost every seral stage of forest". Although certain habitats such as old fields may be more important than others in some regions (see Preferred Habitat) [114,117], most researchers agree that having a variety of habitats in a range of seral stages available over a diversity of terrain—along stream bottoms and on adjacent slopes and uplands—allows American woodcocks to shift habitats according to changes in invertebrate availability brought on by weather changes, and reduces the likelihood that any one habitat will limit the density and/or productivity of an American woodcock population [8,26,50,75,76,79,140].Management practices used in American woodcock habitats include:
Fire: For information on the use of prescribed fire to benefit this species, see Fire Management Considerations.
Silviculture: In large part, forest management programs designed to benefit American woodcocks in the northern range stress the creation of openings and maintenance of aspen and alder; in the southern range, programs stress maintenance of bottomland hardwood and pine forest. This review focuses on these habitats. However, suitable habitat structure for American woodcocks may be found in a variety of habitats in a variety of seral stages, not all of which are listed here.
In a survey based upon expert opinion, even-aged management or clearcutting was generally rated as favorable to American woodcocks. Silvicultural methods that expose soil and create openings, such as site preparation, development of forest roads, and use of large machinery were also rated as favorable . Uneven-aged management or selection cutting was seldom rated as beneficial, because the small patches created in the forest canopy are generally not sufficient to allow enough light to support early-successional, light-demanding plants preferred by American woodcocks [23,27,70,79,163,163]. Selection cutting may also provide roost sites for avian predators, making American woodcocks more vulnerable to predation [26,79].
Selection cutting may benefit American woodcocks if the canopy cover is reduced enough to promote the development of midstory and understory vegetation [26,27,93]. Straw and others  suggested that in hardwood forests, selection cutting may be more beneficial than clearcutting for long-term maintenance of diurnal habitats because clearcutting causes a more radical change in moisture and temperature, and American woodcocks prefer areas with intermediate values of basal area. They further suggested that selection cutting probably is most appropriate when managing stands of shade-tolerant species, whereas clearcutting may be more appropriate for managing shade-intolerant species such as aspen . Ultimately, the effects of timber harvesting on American woodcock depend upon the area, shape, soils, plants present, previous history of the site, structure of the harvested stands and adjacent stands, and the type and intensity of harvesting and site preparation [79,176].
Openings: American woodcocks frequently use clearcuts and other openings created by logging operations, such as roads and landings, in a variety of habitats [23,35]. Researchers recommend prioritizing maintenance of openings that are already being used by American woodcocks, then creating openings in closed areas [9,93,152]. Anecdotal evidence suggests that if no large openings are available, small openings can be enlarged or new openings created, although it is "preferable to enlarge a field that is being used rather than create a new one because it may take several years for a woodcock to use a newly created opening, but an enlarged opening usually is used immediately" . It is preferable to clear old fields that have succeeded to forest than to clear areas that have never been farmed (see Historical land use) .
Creating or maintaining patchy woody-stem cover throughout an opening is likely to benefit American woodcocks. In areas where ground cover is dense and/or uniform, a patchy structure may be created by cutting, burning, mowing, herbicide use, or discing in small areas; these actions may break up homogenous cover and encourage woody stem growth . In areas where woody-stem cover is dense, cutting every 3 to 4 years was recommended to maintain openings . Shrub planting is recommended in areas where woody stems are too sparse. Male American woodcocks are territorial, so in areas where openings are large (a diameter greater than the average distance between males at a singing ground) and woody vegetation is sparse, researchers recommended planting shrubs to increase density of displaying males [93,107]. Specifically, hedgerows, clumps of shrubs, or "islands" of small trees may make a large opening useful as singing grounds for more than one male [93,107].
American woodcocks may use small openings as singing grounds but appear to require large openings as nocturnal habitats. Sites at least 0.25 to 0.5 acre (0.1-0.2 ha) are recommended as singing grounds, although Maxfield  found that the size of the singing ground depended on the height of surrounding trees. Based on his work, clearings >0.5 acre (0.2 ha) can be created where trees are over 25 feet (7.6 m) tall, but openings as small as 0.25 acre (0.1 ha) can be created if surrounding vegetation is shorter. See Singing grounds for more information on this study. Openings >3 acres (1.2 ha), but <100 acres (40 ha) are recommended for nocturnal habitats [7,152]. In Pennsylvania, American woodcocks preferred to use edges rather than interiors of large even-aged stands, but use was more evenly distributed in small even-aged stands .
American woodcocks frequently use shrubby edges between forests and openings, particularly for nesting. To encourage dense shrub and tree sapling growth at forest-opening edges, researchers recommend selectively thinning large trees around the perimeter of openings [93,152,163,176]. In Roscommon and Kalkaska counties in Michigan, six 9-mile² (23.3 km²) areas were clearcut, 2 each at 25%, 50%, and 75% of the area. Numbers of singing males increased substantially (250-360% increase) 1 to 7 years after treatment. The 50% and 75% treatment areas had significantly more males than the 25% areas for all 6 years of the study (P<0.05). This result could not be attributed to regional population trends but apparently reflected alterations in habitat as a result of treatments. Because American woodcocks were primarily found along forest-opening edges, the immediate increases in singing-ground activity were likely associated with the clearing of mature forests and creation of openings, while the long-term increases apparently resulted from subsequent patchy growth within the clearings that created "finer-grained interspersion of forest and field habitats" and thus greater availability of edge habitats .Shrublands: Pure alder: Alder habitats are the most heavily used habitats in the northern part of the American woodcock's range [93,107,132]. Preferred alder habitats are generally <30 years old, but the age of stands that American woodcocks use depends upon the rate at which invading trees replace alder .
Alder habitat generally becomes less suitable for American woodcocks over time [93,149,151]. In Pennsylvania, preferred alder habitats were generally 10 to 20 years old and had a canopy cover of about 70% and a ground cover of about 30%. The author described succession of alder habitats in Pennsylvania as follows :
"Stem growth is most vigorous from 1 to 8 years. This period represents the invasion of alder into old fields or similar sites not inhabited by other woody plants. With little or no competition stems grow vigorously. At about 10 years crowding becomes evident. New stem growth then levels off and remains static for another 10 years. After about 20 years, many stems begin to die off from old age and competition. The remaining few stems continue to flourish for another 5 to 10 years. Very few stems reach 30 years of age. Unless rejuvenated, alder types in Pennsylvania are usually replaced by trees."
At the Moosehorn National Wildlife Refuge, more male American woodcocks used strip-cut alder stands than uncut alder stands as singing grounds (P<0.10), but use declined over time as alder height increased. Five years after strip-cutting, use of both stands was similar [149,151]. Alder thickets 6 to 12 feet (1.8-3.7 m) tall with a closed crown were preferred . In Penobscot County, Maine, American woodcocks used alder habitats averaging 8 years old but did not use alder habitats averaging 11 years old .
Because of the importance of young alder habitats to American woodcocks, maintaining alder stands in early succession can benefit American woodcocks [46,107,137,152]. Researchers generally recommend strip cutting alder stands at 20- to 30-year rotations and clearcutting a portion of the habitat on a 2- to 5-year cutting cycle [93,107,151,152]. Other management methods such as prescribed fire may be applied on a similar rotation as cutting. See these sources for specifications on the size and distribution of cuts, rotation age, and reentry period for pure alder stands: [93,107,149,151,152].
Sepik and others  suggested that if alder habitats are located on soils of varying moisture, strips be clearcut along the moisture gradient. Differences in moisture may result in varying plant growth after cutting, creating a range of suitable American woodcock habitats  and increasing the probability that a given clearing attracts American woodcocks . However, because strip cuttings in lowland areas of Moosehorn National Wildlife Refuge were used more frequently by American woodcocks than dry, upland areas, particularly during dry conditions in July and August, Reardon  recommended that strip cuttings be placed in lowland areas.
Mixed alder: Because American woodcocks occur in pure alder habitats more frequently than mixed alder habitats , researchers recommend managing habitats in favor of alder over other woody species [93,152]. In Oswego County, New York, American woodcocks used early seedling, late seedling, and sapling mixed- and pure-alder stands during the day. American woodcocks were more abundant in pure alder stands—particularly sapling stands—that were 7 to 25 years old, had some exposed mineral soil, high overstory and understory density, moderate ground cover, and high earthworm numbers . In areas where alder is mixed with other species, Sepik and others  recommended clearcutting the entire area, rather than strip cutting small parts of the area as recommended for pure alder stands. Liscinsky  recommended cutting or using herbicides on other hardwoods in mixed stands to favor alder. The author also recommended establishing alder by planting seedlings or by direct seeding at suitable sites where alder is absent or patchy .
Other shrubs: Researchers recommend managing moist-soil shrub habitats (e.g., willow and dogwood) for American woodcocks similarly to alder habitats (e.g., strip cutting on a 20-year rotation across moisture gradients) [93,106]. Thickets of shrub species that sprout can be clearcut during dormancy to stimulate new growth . Preferred shrubs can be favored by removing overstory trees [93,163]. Planting shrubs is also recommended .Forests: Aspen: Aspen ecosystems are important habitats for American woodcocks in the North [42,53,93,107]. Sapling and small pole-sized aspen stands, typically <30 years old, are considered "optimum" for American woodcock diurnal habitats in Pennsylvania . In Maine, American woodcocks preferred aspen forests from 15 to 30 years old and <25 feet (7.6 m) tall . Seedling-stage aspen stands—particularly those >3 years old—may be too dense [53,140], and mature stands may be too sparse  for American woodcocks.
Because of rapid vegetation growth in some sites, particularly areas with fertile soil, aspen clearcuts may be short lived. Aspen clearcuts may maintain suitability for American woodcocks only 1 to 2 years after clearcutting. In Prince County, Wisconsin, up to 28 American woodcocks were captured in an aspen clearcut 1 to 2 years after cutting; 3 years after clearcutting, 6 American woodcocks were captured. This was attributed to "rank" vegetation growth. American woodcocks in this study apparently benefited from exposed bare ground on skid trails and deck sites created during clearcutting. These authors found that "mechanical harvests which produced the most soil disturbance also made cutting areas most attractive to American woodcock" and suggested that use of aspen clearcuts by American woodcocks may be maintained by annually removing vegetation from trails and creating small openings with a bulldozer . Robinson and others (abstract by ) studied American woodcock populations 6 years before and 2 years after clearcutting a 235-acre (95 ha) mature aspen forest in the upper peninsula of Michigan. Prior to clearcutting, American woodcock densities ranged from 0 to 0.1/acre. The first summer after clearcutting, American woodcock densities ranged from 0.2/acre to 0.5/acre. However, the authors noted that American woodcock use of the clearcut was reduced during dry periods, when individuals moved to wetter areas in nearby uncut stands. Soil moisture was lower in the regenerating clearcut than in the adjacent uncut stand, and earthworm biomass in the clearcut was "below optimum levels" during dry periods. The authors recommend clearcutting mature aspen forest across a soil moisture gradient—including cutting near swamps—and spacing clearcuts so nearby tree and shrub cover is available .
To keep aspen in early succession, a cutting rotation of 20 years was recommended for American woodcock habitat management in Pennsylvania . Cuts every 5 to 7 years were recommended to maintain brood cover in lowland areas . See these sources for specifications on the size and distribution of cuts, rotation age, and reentry period for aspen stands: [48,93,152].
Bottomland hardwood: Bottomland hardwood forests are important habitats for American woodcocks, particularly in the South [54,59,79,167]. A review stated that selectively thinning bottomland hardwood forest may increase foliage height diversity and production of ground-level vegetation , which may benefit American woodcocks. In the Mississippi Delta, more wintering American woodcocks were flushed during the day from sapling and mature bottomland hardwood forests than from pole-sized bottomland hardwood forest. However, stand age appeared less important than the presence of a dense understory within the stand . See Winter diurnal habitats for information on this study. The authors suggested that to provide diurnal cover for American woodcocks, bottomland hardwood forests be clearcut in "small" blocks to create young sapling stands; they also suggest selection cutting in pole and mature stands to maintain a partial canopy and encourage the development of mid- and understory vegetation .
Conifer: In the North, conifer forests may be important for American woodcock survival during drought , and some conifers mixed with hardwoods may be important at nest and brood sites [32,45]. American woodcocks frequently use clearcuts in conifer stands. In northeastern New Brunswick, 2- to 16-year-old clearcuts in spruce-balsam fir and jack pine-red spruce/black spruce forests were frequently used by male American woodcocks as singing grounds . In another study in New Brunswick, American woodcocks used clearcuts in conifer forest, particularly in lowland areas. Displaying male American woodcocks used young (<4 years old) and old (≥4 years old) clearcuts in lowland spruce-balsam fir forest and upland mixed hardwood-conifer forest and lowland black spruce plantations that were <10 years old. Significantly more male American woodcocks were heard in lowland clearcuts than upland clearcuts (P≤0.05). Clearcuts were typically several hundred ha and dominated by red raspberry (Rubus strigosus), pin cherry, and balsam fir. Black spruce plantations often had higher numbers of displaying male American woodcocks than other sites, but this pattern was not consistent .
Plantations: American woodcocks frequently use pine plantations, particularly on wintering grounds [11,67]. Young (typically <5 years old) pine plantations where pines are <10 feet (3 m) tall and thickets of hardwood seedlings, blackberry, and cane grow under the pines are frequently used by American woodcocks [26,75,82]. Pine plantations where pines are 10 to 30 feet (3-9 m) tall (typically <15 years old) are also used [75,82]. Pine plantations are rarely used once the canopy closes and shrub densities decline [11,26,82]. Thinning of closed-canopy pine plantations may maintain their suitability for American woodcocks by increasing light penetration to the forest floor and promoting understory growth [26,76]. In Massachusetts, American woodcocks used conifer plantations during the first 5 to 6 years . Dense monocultures of longleaf, shortleaf, loblolly, or slash pines tend to acidify the soil and degrade habitat for American woodcock; however, these pine plantations can vary from good to poor American woodcock habitat depending upon the understory, litter layer, and soil. Pine plantations that are intensively managed typically have sparse ground and midstory vegetation, making them less attractive to American woodcocks. Less intensive methods of plantation establishment may create patchy sites more favorable to American woodcocks . A very sparse pine forest with a dense hardwood understory is more suitable for American woodcocks than dense pines that shade the forest floor and often have little suitable understory . For more information, see Indirect Fire Effects.
American woodcocks also use hardwood plantations. Roberts and others  documented low use of sapling and pole-sized eastern cottonwood plantations in the Mississippi Delta region. Low use of sapling eastern cottonwood plantations was attributed to cultivation that resulted in little ground cover, and low use of pole-sized plantations was attributed to dense Johnson grass (Sorghum halepense). The authors suggested that eastern cottonwood plantations may provide suitable habitat for American woodcocks as long as understories are not too sparse .
Other forest: A variety of other forests can be managed to benefit American woodcocks. Recommended rotation periods vary according to local conditions and habitat [23,107], but in general, rotations <40 years are recommended for American woodcock habitat management. In New England and the Maritime Provinces, Coulter and Baird  recommended managing forested habitat on a 10- to 15-year cutting cycle with rotations of <40 years. In Pennsylvania, young growth <25 years of age was considered "ideal" American woodcock habitat . McAuley and others  recommended maintaining ≥25% of the land in early-successional habitat by clearcutting blocks ≥5 acres (2 ha) or cutting 100-foot (30 m) wide strips in mature forest on about a 40-year rotation. In Wisconsin, Gregg  recommended that in regions where loamy soils predominate, 25%, 45%, and 65% of the area should consist of early-successional forest types required to maintain low, medium, or high American woodcock densities, respectively. Rittenhouse and others  developed a habitat suitability index model for diurnal habitats in American woodcock breeding and migration sites in the Central Hardwoods Region of the Midwest. They considered diurnal habitat with maximum suitability for American woodcocks to be mesic sites 1 to 10 years old . In Boone County, Missouri, American woodcocks displayed in 1- to 7-year-old clearcut oak-hickory forests. Not all clearcuts were used the 1st year after clearcutting, but all clearcuts were used 2 years later . At the Moosehorn National Wildlife Refuge, hardwood forests >15 years old were rarely used , but male American woodcocks increased use of large, contiguous hardwood forest as singing grounds after small (100 × 100 feet (30 × 30 m)) clearcuts were created . Reardon  stated that habitat created the first 15 to 20 years immediately following cutting or burning of a forest was most important to American woodcocks.
Grazing: Moderate and/or infrequent livestock grazing may aid American woodcocks by retarding succession and reducing vegetation density, but heavy grazing is detrimental [26,40,53,79,86,89,101]. Dessecker and McAuley  noted that American woodcocks rarely used intensively grazed fields with extensive areas of very short grass but that "brief periods of intense grazing" by livestock may enhance American woodcock habitats. In Cape May, New Jersey, American woodcocks used ungrazed "overgrown" pasture more than heavily grazed pasture with low, uniform cover . Lightly grazed cattle pastures provided suitable display sites for male American woodcocks in Massachusetts . In longleaf pine forest on the Conecuh National Forest, American woodcock abundance was compared among burned sites that were grazed and ungrazed. Grazed sites had significantly more American woodcocks in the year of the fire than later (P<0.05) :
|Mean American woodcock flushes/ha in grazed and ungrazed longleaf pine forests that varied in the length of time since application of winter prescribed fire |
|Length of time since prescribed fire||Grazed||Ungrazed|
|Year of fire||1.07a||0.55b|
|1 year after fire||0.25bc||0.08bc|
|2 years after fire||0.05bc||0.01c|
|All sites combined||0.47bc||0.21bc|
|a Means with a common letter did not differ significantly (P>0.05).|
In Pennsylvania, cattle grazing on a site with tall herbs increased American woodcock use in the short term (<2 years), but "overgrazing" in subsequent years eventually made the site less suitable, and American woodcocks shifted to ungrazed areas. The author recommended that bottomland hardwood habitats be subjected to <25 animal-days of cattle grazing/acre at 5-year grazing intervals .
Mowing: Mowing may improve American woodcock habitats. At the Oklahoma State University Ecology Preserve, male American woodcocks displayed in previously unused tallgrass prairie after mowing; apparently, male American woodcocks avoided unmowed tallgrass prairie because vegetation was too tall and dense to perform display flights . In Nacogdoches County, Texas, American woodcocks roosted in mowed areas at night . However, mowing can be detrimental if it reduces woody stem growth too much . Mowing in strips or patches may be more beneficial to American woodcocks than homogenous mowing [79,106]. Some researchers recommended mowing patches in fall after growth has ceased to create foraging areas for American woodcocks in winter [26,79]. Glasgow  suggested mowing in spring and summer over mowing in late summer, because late summer mowing may remove too much cover. Other researchers suggested mowing after the nesting season to prevent destruction of nests .
Herbicides: Herbicides are sometimes recommended to create or maintain openings for American woodcocks, but they may be ineffective or effective for only a short time [41,93,152]. In Michigan, 3 areas with dense ground cover in lowland alder habitats that were not used by American woodcocks were sprayed with herbicides in 0.1-acre (0.04 ha) plots. One year later, more American woodcock sign occurred in treated areas than untreated areas (P<0.05) because treated plots had areas barren of grasses and sedges while untreated areas had dense vegetation . In Maine, Sepik and others  recommended that herbicides be applied in spring to top-kill alder and cause sprouting but cautioned that standing dead woody debris created by herbicides may not provide suitable openings. In Nacogdoches County, Texas, herbicide use in densely vegetated old fields was not recommended because it would likely result in thick layers of dead groundlayer vegetation, which is not conducive to nighttime roosting and feeding activity . In fields where tall herbaceous vegetation reduced habitat suitability for American woodcocks, herbicides appeared to be "impractical as a tool" because the results were too short-lived and frequent application was necessary .
Water management: Reynolds and others  suggested that because earthworm abundance is directly related to soil moisture and soil temperature, management regulating these characteristics, such as irrigation and manipulation of weirs, could favor American woodcocks. Krementz  suggested that because flooding is a major cause of large-scale winter movements that may contribute to mortality, flood control may benefit some American woodcock populations (see Diseases and Sources of Mortality). However, draining wetlands or lowering the water table may reduce earthworm abundance . Krementz and Jackson  recommended "plugging" old drainages to raise the water table to benefit earthworms and thus American woodcocks. However, manipulation of water levels may not be feasible or desirable [46,155]. In Louisiana, fields that were heavily used by American woodcocks, but subsequently drained, were no longer used .
Landscape management: Researchers suggest that American woodcock habitat management focus on creating diurnal and nocturnal feeding and roosting sites, singing grounds, and nest and brood cover within close proximity to each other [63,70,97,151]. Based upon the average distance between these habitats, this means creating or maintaining openings with sparse ground cover and pockets of shrubs within approximately 660 feet (200 m) of forests with shrubby understories and soils, such as moist loams, that support abundant earthworms [7,107,155]. Daily crepuscular movements >4,900 feet (1,500 m) are rarely reported and most are <3,300 feet (1,000 m); thus, in a review Parris  recommends locating diurnal and nocturnal habitats at least <3,300 feet apart.
The relative amount of diurnal and nocturnal habitats and their optimal spacing are not thoroughly understood . Diurnal forest habitat is essential to both genders and all ages of American woodcocks on both the breeding and wintering ranges and may be the factor most limiting to American woodcocks . In Pennsylvania, examination of American woodcock habitat use at multiple scales revealed that at small spatial scales, American woodcocks were associated with fragmented landscapes with a variety of interspersed components (i.e., forests, fields, and their edges), but at broad scales American woodcocks were associated with landscapes that were less fragmented and less heterogeneous. That is, fine-scale selection of heterogeneous habitat occurred within more homogenous broad-scale landscapes . Sepik and others  speculated that 1 opening for every 100 acres (40 acres) would be "adequate" for American woodcocks in the Northeast. Mendall and Aldous  speculated that "since the majority of singing grounds are separated from each other by 200 or more yards, and since areas must be allowed for suitable nesting territories, it is probable that, under optimum cover conditions, a ratio of one singing ground per 6 or 7 acres of (diurnal) cover is a satisfactory figure" for American woodcocks in the Northeast.
Hunting: The American woodcock is an important game species that is hunted in 34 states and 5 Canadian provinces. As of 1989, the leading American woodcock harvest states were Maine, Michigan, New York, Pennsylvania, and Wisconsin. American woodcocks were little hunted in the South, except in Louisiana, where they were generally taken incidentally . Results of surveys as of 2000 indicated that American woodcock harvest and number of American woodcock hunters declined from the early 1980s to 2000 (Kelley 2000 cited in ).
General observations suggest that American woodcocks frequently occur in burned areas and occupy burned areas soon after fire. Male American woodcocks often use recent burns as singing grounds in the spring. During a spring prescribed fire, 1 male American woodcock was observed displaying "normal courtship behavior" in a burned field of grasses and "weedy" forbs in Marion County, Illinois, while parts of the field still burned <20 feet (6 m) away . At the Moosehorn National Wildlife Refuge, male American woodcocks used 14 open areas as singing grounds both before and after a fire that occurred during the peak of the courtship period .INDIRECT FIRE EFFECTS:
American woodcocks use burned areas during the day and at night throughout their range. In Portage County, Wisconsin, courting males used "the blackened remains" of a willow thicket burned the previous year . American woodcocks occurred in blueberry habitat the year of and the year after a spring prescribed fire at the Moosehorn National Wildlife Refuge . In Carlton County, Minnesota, American woodcocks used burned upland brush "where the birds selected the nonburned or lightly burned patches" during the day . In West Virginia, male American woodcocks displayed on fields prescribed burned the previous year (Mathews 1972 cited in ). In Louisiana, wintering American woodcocks aggregated in burned fallow fields at night . In Nacogdoches County, Texas, American woodcocks were captured in winter on an upland site after fall prescribed burning and discing and on a lowland site after fall mowing and prescribed burning. They appeared to prefer sites that been burned but not disced . On the Conecuh National Forest, American woodcocks occurred in longleaf pine forests the winter of a prescribed fire as well as 1 and 2 years after the fire .
Fire effects on vegetation: The effect of fire on American woodcocks depends upon the fire's short and long-term effects on vegetation structure. In the short term, fire may benefit American woodcocks by reducing ground cover and litter and exposing bare ground so that individuals can probe easily for earthworms [16,41,67,67,169]. In the long term, fire may reduce earthworm populations by altering soil characteristics, food resources, and protective cover . Fire may negatively affect American woodcocks in the short term, if it removes too much protective cover in the midstory or understory [16,65,107], but in the long term, American woodcocks may benefit from increased woody stem growth as a result of fire [16,65,107].
American woodcocks may benefit from fire-caused reduction of ground cover and litter. In Nacogdoches County, Texas, American woodcocks made frequent use (50% of observations) of an upland old field site that was prescribed burned the previous summer. High use was attributed to reduction of Bermuda grass and litter, and exposure of bare ground resulting from the "spotty" fire. In the winter prior to the fire, no American woodcocks were recorded in the old field . In Hyde County, North Carolina, more American woodcocks occurred in old fields prescribed burned 1 to 2 years prior (60-80% of observations) than in unburned control plots (16-19% of observations), possibly because vegetation cover on burned plots was less than that on control plots . In Louisiana, no American woodcocks were observed in a 3-acre (1.2 ha) fallow field with dense hairy crabgrass (Digitaria sanguinalis), broadleaf signalgrass (Brachiaria platyphylla), smartweed, and cocklebur (Xanthium spp.) cover prior to a prescribed fire. Immediately following the fire, however, 18 American woodcocks were observed in the field, apparently responding to the reduced grass and increased bare ground . In Georgia, American woodcocks used old fields burned under prescription in winter and herbicide-treated old fields more often than harvested agricultural fields (P<0.05). However, use of burned and herbicide-treated old fields was similar to use of other treatments and the control :
Mean number of American woodcocks/observer-hour in old fields subjected to 5 treatments and an untreated old field in Oconee, Greene, and Morgan counties, Georgia 
|Harvested agricultural fields||3||0.6a|
|Grazed or mowed within the last year*||4||4.0ab|
|Prescribed burned or herbicide-treated within the last 2 years*||6||4.7b|
|Untreated old field||7||2.0ab|
|aTreatments with the same letters did not differ significantly (P>0.05).|
|*Data for burned and herbicide-treated sites and grazed and mowed sites were pooled because visual observations indicated that sites were similar in vegetation structure.|
Wintering American woodcock use of longleaf pine forest on the Conecuh National Forest appeared to be highest soon after fire and declined thereafter. Comparison of American woodcock abundance during the day revealed that during 2 winters, abundance was significantly greater at sites burned during the winter of the study than at sites burned ≥2 years prior to the study. During the 2nd winter of the study, American woodcocks were significantly more abundant at sites burned 1 year prior than at sites burned ≥2 years before the study. No American woodcocks were found at unburned control sites (P≤0.05 for all variables) :
|Mean American woodcock abundance, ground cover, and soil invertebrate abundance in winter-burned longleaf pine forests |
|Length of time since prescribed fire||American woodcock abundance
|Soil invertebrate abundance
|aMeans in the same column with a common letter did not differ significantly (P>0.05).|
|**Ground cover = % cover by short (>0.3 m tall, but <2 m tall) vegetation + % leaf litter cover.|
This study suggested that American woodcocks selected recently burned (≤1 year postfire) longleaf pine forest. Mean total ground cover—which was dominated by pineland threeawn (Aristida stricta), bluestem (Andropogon spp.), and longleaf pine seedlings—and leaf litter cover were higher at sites burned ≥2 years prior to the study than at sites burned more recently (P≤0.05), suggesting that American woodcocks benefited from a reduction in short vegetation and leaf litter caused by fire. Because soil invertebrate abundance was similar among sites, differences in American woodcock abundance in this study were likely the result of vegetation structure and/or ground cover rather than food availability . Conversely, American woodcock use of longleaf pine/bluestem (Andropogon and Schizachyrium spp.)-panic grass (Dichanthelium spp.) forest in west-central Louisiana appeared to be highest at sites burned at longer intervals (≥4-year) than sites burned more frequently :
|Number of American woodcocks recorded during morning point-count surveys in longleaf pine forest in west-central Louisiana with different fire-return intervals .|
|Return interval of winter prescribed fire||Number of American woodcocks|
|1 year||not detected|
|2-3 years||not detected|
|Unburned for 20 years||5|
Sites with short fire-return intervals (<4 years) had sparse midstories dominated by longleaf pine saplings and dense ground cover of grasses, whereas sites with longer fire intervals (≥4 years) had well-developed midstories dominated by hardwoods and ground cover dominated by woody plants .
Anecdotal evidence suggested that prescribed fire in Wisconsin stimulated growth of alder and aspen and exposed bare ground  that was likely to be favorable to American woodcocks. Mendall and Alduous  described the importance of frequent fire in creating American woodcock habitats in the Northeast: "light or only moderately heavy fires through an area were usually followed by immediate growths of gray birch and aspen. Pine, spruce, or fir, coming in more slowly, at first form an understory during the dominance of the hardwoods, later becoming the climax forest. It is during the few years in which the softwoods are present as an understory that optimum woodcock conditions occur". Reardon  agreed that fire is important in creating and maintaining habitat for American woodcocks: "from the standpoint of woodcock cover, it is the first 15 or 20 years immediately following cutting or burning of the forest that is of greatest importance. After that, the woodcock ordinarily makes little use of a stand".
Application of prescribed fire in combination with clearcutting and other silvicultural practices may create and maintain edges and openings for American woodcocks. At the Moosehorn National Wildlife Refuge, American woodcocks used clearcuts with unburned slash more often than clearcuts with burned slash (P<0.05), often utilizing scattered slash-free pockets at night. However, the authors suggested that if the slash load is heavy, prescribed fire or other treatments may be necessary to provide microsites for roosting . Application of prescribed fire in clearcuts may produce a more diverse shrub layer, expose more mineral soil, and increase light required by some plant species such as aspen than clearcutting alone. In addition, the landscape following fire is typically patchy and variable, unlike that created by clearcutting alone. The edges of burned sites are typically more convoluted, and large patches of live trees are often found within the disturbed area (review by ). However, in northeastern Minnesota, American woodcock population densities were similar (0.2 male/ha) in early-successional forests created by fire and those created by logging 2 years prior to the study . Two years after treatment, burned areas had greater heterogeneity with higher densities of dead trees, wider size ranges of dead trees, and greater heterogeneity in the shrub layer than logged areas. Logged areas had higher densities of live trees, more live tree species, and wider size ranges of live trees than burned areas. However, these differences in plant species composition and stand structure are not typically cited as being important to American woodcocks and thus perhaps did not result in substantial differences in habitat use by the species .
American woodcocks may benefit indirectly from fire when it increases openings and edge habitat [3,107]. In 1976, a lightning-caused wildfire burned from late July to late September over 64,000 acres (26,000 ha) of mixed hardwood-conifer forest, conifer forest, tamarack-red maple bog, and shrubby bog habitats within and adjacent to the Seney National Wildlife Refuge. The fire "burned patchily and with varying degrees of intensity". During postfire years 1 and 2, American woodcocks were not observed on burned sites, but they became more abundant in unburned bog and mixed hardwood-conifer forest plots, likely benefiting from the increase in available edge habitat. Bird species richness and diversity were lower on burned plots relative to unburned plots throughout the 3 year study, but significant differences were detected only on study plots where most trees were killed and shrubs were consumed (P≤0.10) .
Fire effects on American woodcock foods: Fire may have a substantial effect on soil invertebrates and thus on American woodcocks. The vulnerability of a species of soil invertebrate to direct mortality from fire depends on its location in the soil profile and the depth of heat penetration, which depend upon fire severity . Invertebrate species in surface litter are more vulnerable to fire mortality than those in mineral soil [17,98]. Because many invertebrates use different habitats throughout their life, seasonality of fire likely interacts with phenology for many invertebrates . Some insects lay their eggs or exist in immature forms in the upper soil layers and are more likely to be killed by fire during these life stages . For example, grasshoppers winter as larvae in the upper soil layers, and because they are relatively immobile at this time, spring fires may cause higher mortality than fires occurring at other times of year (Komarek 1970 cited in ).
The indirect effects of fire on soil invertebrates are typically more important than the direct effects ([10,18], Rice 1932 cited in ). Fire alters soil characteristics—such as soil moisture, temperature, and pH—food resources, and protective cover that influence soil invertebrates. Indirect fire effects on soil invertebrates vary greatly with fire severity, frequency, and seasonality; plant and invertebrate communities affected; and region .
Earthworms are often reduced by fire [1,18]. In the short term, fire and subsequent alterations in vegetation structure may decrease soil moisture and increase soil temperatures to levels intolerable to earthworms (review by ). In longleaf pine forests, earthworm numbers were 4 times greater in the first 0 to 2 inches (0-5 cm) of unburned mineral soil than in the corresponding portion of burned soil. The researchers suggested that the decrease was due to xeric soil conditions after the fire (Heyward and Tissot 1936 cited in ). In prairie habitat in Illinois, earthworm numbers were similar at burned and unburned sites in the spring when soil moisture content was similar between the sites, but as soil moisture increased on the unburned site and declined on the burned site in late April and May, earthworm numbers in the unburned site increased while those on the burned site decreased. The moisture decline on the burned site was associated with increased evaporation caused by lack of surface vegetation (Rice 1932 cited in ). Other studies suggested that some earthworm species may be unaffected by fire or may increase after fire. On the Conecuh National Forest, no differences in soil invertebrate abundance was detected among longleaf pine forests that varied in the length of time since winter prescribed fire (1 to >10 years) . In tallgrass prairie at the Konza Prairie Research Natural Area in Kansas, the biomass of 2 species of native prairie earthworms increased 67% to 135% after 2 years of annual prescribed fire, but biomass of a nonnative earthworm decreased 62% following these treatments, a difference attributed to the different physiological requirements of the 3 earthworm species . Long-term responses of earthworms to fire were little studied as of this writing (2010). Higher plant productivity after fire may have a positive effect on earthworms in the long term by increasing food resources (review by ). Fire may also raise soil pH . This may increase earthworm abundance, particularly in areas of the Northeast where soil pH tends to be low (Pearce 1940 unpublished report cited in ). For a review of direct and indirect fire effects on other soil invertebrates, see Chandler and others .FIRE REGIMES:
Historically, the season, frequency, and scale of disturbance varied considerably in American woodcock habitats. Researchers recommend application of a variety of management methods at various times and scales to mimic the historical disturbance patterns .
Season: Season of fire may have important consequences for American woodcocks. "Cool-season" fires or fires occurring from winter to early spring tend to promote woody vegetation, so they are generally recommended for American woodcock habitat management [76,79]. American woodcock use of winter, prescribed-burned longleaf pine forests and pine plantations in the South [67,92] suggests that cool-season prescribed fire is amenable to American woodcocks (see Indirect Fire Effects). Cool-season fires remove ground cover and plant litter, so American woodcocks have easy access to the soil for foraging, but they also retain patches of woody vegetation 3 to 7 feet (1-2 m) above ground [76,79]. Escape and protective cover may be particularly important during nesting in spring, when females are often associated with forest-field edges, and during molt in mid-summer and into fall, when American woodcocks often increase use of dense habitats such as alder thickets (see Preferred Habitat). Reduction of cover during these times, particularly in areas where cover is limited, may expose American woodcocks to predators, hunters, and weather .
Fire may destroy important nesting cover. Krementz and Jackson  recommended that prescribed fire be applied just prior to spring green-up, because fires at this time may reduce protective cover for shorter time periods than fires occurring from late summer to early winter. However, nesting occurs just prior to spring green-up (see Reproduction and development), and fires that occur at this time may cause nest mortality and reduce nesting cover. Fires that occur after the nesting season are often considered more suitable for ground-nesting birds in general [58,70]. However, Vogl  stated that loss of American woodcock nests to fire was likely not substantial because females may renest, and suggested that the risk of minor nest losses should not be used to determine the timing of prescribed fire. Rather, the desired effect of fire on vegetation should be the primary determinant of American woodcock habitat management because plant succession was likely to be of greater consequence to American woodcocks than direct mortality . To reduce the total impact of fire on American woodcock habitats during cool-season prescribed fire, Kruse and Piehl  recommended patchy fires that have less impact on total vegetation in an area than homogenous fires.
Frequency: Fire frequency may also influence suitability of habitats for American woodcocks. Annual fall burning may be harmful to American woodcocks due to a reduction of nesting cover available in the subsequent spring . In the Northeast, Sepik and others  recommended prescribed fire every 2 years to eliminate invading woody vegetation in clearings used by American woodcocks as singing grounds and nocturnal habitats. However, vegetation on poor soils may be slower to recover than vegetation on rich soils, requiring less frequent application of prescribed fire to maintain openings. Vogl  recommended a mosaic of 1- to 4-year-old burned areas as a means to ensure a mixture of cover for American woodcocks in Wisconsin.
Extent: Because American woodcocks require diurnal and nocturnal habitats within close proximity, the extent of fire is likely important to American woodcocks. If large areas are burned uniformly, the resulting vegetation may limit the food and cover available to American woodcocks, whereas burning small areas or large areas heterogeneously will likely benefit American woodcocks by offering a wider choice of habitats within an individual's home range [65,169]. Irving  suggested that burned areas <40 acres (16 ha) would probably have little effect on juxtaposition and interspersion of habitats available to American woodcocks, and advised that "the smaller the area of an individual burn, the less chance that it will have an adverse effect on the pattern" . In general, patchy fires of mixed severity are more likely to create habitats suitable to wildlife in general and American woodcocks in particular, because such fires provide the greatest variety in plant succession and edges. Conversely, fires that are very large and/or homogeneous likely have a negative effect on wildlife in general and American woodcocks in particular .
|Fire regime information on vegetation communities in which American woodcock may occur. This information is taken from the LANDFIRE Rapid Assessment Vegetation Models , which were developed by local experts using available literature, local data, and/or expert opinion. This table summarizes fire regime characteristics for each plant community listed. The PDF file linked from each plant community name describes the model and synthesizes the knowledge available on vegetation composition, structure, and dynamics in that community. Cells are blank where information is not available in the Rapid Assessment Vegetation Model.|
|Northern Great Plains|
|Vegetation Community (Potential Natural Vegetation Group)||Fire severity*||Fire regime characteristics|
|Percent of fires||Mean interval
|Northern Plains Grassland|
|Central tallgrass prairie||Replacement||75%||5||3||5|
|Surface or low||13%||28||1||50|
|Northern tallgrass prairie||Replacement||90%||6.5||1||25|
|Surface or low||2%||303|
|Southern tallgrass prairie (East)||Replacement||96%||4||1||10|
|Surface or low||3%||135|
|Surface or low||76%||4|
|Northern Plains Woodland|
|Surface or low||98%||7.5|
|Northern Great Plains wooded draws and ravines||Replacement||38%||45||30||100|
|Surface or low||43%||40||10|
|Great Plains floodplain||Replacement||100%||500|
|Vegetation Community (Potential Natural Vegetation Group)||Fire severity*||Fire regime characteristics|
|Percent of fires||Mean interval
|Great Lakes Grassland|
|Mosaic of bluestem prairie and oak-hickory||Replacement||79%||5||1||8|
|Surface or low||20%||2||33|
|Great Lakes Woodland|
|Great Lakes pine barrens||Replacement||8%||41||10||80|
|Surface or low||83%||4||1||20|
|Jack pine-open lands (frequent fire-return interval)||Replacement||83%||26||10||100|
|Northern oak savanna||Replacement||4%||110||50||500|
|Surface or low||87%||5||1||20|
|Great Lakes Forested|
|Northern hardwood maple-beech-eastern hemlock||Replacement||60%||>1,000|
|Conifer lowland (embedded in fire-prone system)||Replacement||45%||120||90||220|
|Conifer lowland (embedded in fire-resistant ecosystem)||Replacement||36%||540||220||>1,000|
|Great Lakes floodplain forest|
|Surface or low||93%||61|
|Great Lakes spruce-fir||Replacement||100%||85||50||200|
|Minnesota spruce-fir (adjacent to Lake Superior and Drift and Lake Plain)||Replacement||21%||300|
|Surface or low||79%||80|
|Great Lakes pine forest, jack pine||Replacement||67%||50|
|Surface or low||10%||333|
|Surface or low||67%||500|
|Maple-basswood mesic hardwood forest (Great Lakes)||Replacement||100%||>1,000||>1,000||>1,000|
|Surface or low||89%||35|
|Northern hardwood-eastern hemlock forest (Great Lakes)||Replacement||99%||>1,000|
|Surface or low||76%||11||2||25|
|Surface or low||81%||85|
|Red pine-eastern white pine (frequent fire)||Replacement||38%||56|
|Surface or low||26%||84|
|Red pine-eastern white pine (less frequent fire)||Replacement||30%||166|
|Surface or low||23%||220|
|Great Lakes pine forest, eastern white pine-eastern hemlock (frequent fire)||Replacement||52%||260|
|Surface or low||35%||385|
|Eastern white pine-eastern hemlock||Replacement||54%||370|
|Surface or low||34%||588|
|Vegetation Community (Potential Natural Vegetation Group)||Fire severity*||Fire regime characteristics|
|Percent of fires||Mean interval
|Northern coastal marsh||Replacement||97%||7||2||50|
|Eastern woodland mosaic||Replacement||2%||200||100||300|
|Surface or low||89%||4||1||7|
|Rocky outcrop pine (Northeast)||Replacement||16%||128|
|Surface or low||52%||40|
|Surface or low||65%||12|
|Oak-pine (eastern dry-xeric)||Replacement||4%||185|
|Surface or low||90%||8|
|Northern hardwoods (Northeast)||Replacement||39%||>1,000|
|Eastern white pine-northern hardwoods||Replacement||72%||475|
|Surface or low||28%||>1,000|
|Northern hardwoods-eastern hemlock||Replacement||50%||>1,000|
|Surface or low||50%||>1,000|
|Appalachian oak forest (dry-mesic)||Replacement||2%||625||500||>1,000|
|Surface or low||92%||15||7||26|
|Northeast spruce-fir forest||Replacement||100%||265||150||300|
|Southeastern red spruce-Fraser fir||Replacement||100%||500||300||>1,000|
|Vegetation Community (Potential Natural Vegetation Group)||Fire severity*||Fire regime characteristics|
|Percent of fires||Mean interval
|South-central US Grassland|
|Southern tallgrass prairie||Replacement||91%||5|
|Surface or low||93%||3||1||4|
|South-central US Woodland|
|Surface or low||99%||3.2|
|Interior Highlands dry oak/bluestem woodland and glade||Replacement||16%||25||10||100|
|Surface or low||80%||5||2||7|
|Oak woodland-shrubland-grassland mosaic||Replacement||11%||50|
|Surface or low||33%||17|
|Interior Highlands oak-hickory-pine||Replacement||3%||150||100||300|
|Surface or low||97%||4||2||10|
|Surface or low||96%||4|
|South-central US Forested|
|Interior Highlands dry-mesic forest and woodland||Replacement||7%||250||50||300|
|Surface or low||75%||22||5||35|
|Gulf Coastal Plain pine flatwoods||Replacement||2%||190|
|Surface or low||95%||5|
|West Gulf Coastal plain pine (uplands and flatwoods)||Replacement||4%||100||50||200|
|Surface or low||93%||4||4||10|
|West Gulf Coastal Plain pine-hardwood woodland or forest upland||Replacement||3%||100||20||200|
|Surface or low||94%||3||3||5|
|Surface or low||58%||100|
|Southern floodplain (rare fire)||Replacement||42%||>1,000|
|Surface or low||58%||714|
|Surface or low||94%||6|
|Vegetation Community (Potential Natural Vegetation Group)||Fire severity*||Fire regime characteristics|
|Percent of fires||Mean interval
|Southern Appalachians Grassland|
|Surface or low||44%||16|
|Eastern prairie-woodland mosaic||Replacement||50%||10|
|Surface or low||50%||10|
|Southern Appalachians Woodland|
|Appalachian shortleaf pine||Replacement||4%||125|
|Surface or low||92%||6|
|Surface or low||49%||55|
|Southern Appalachians Forested|
|Bottomland hardwood forest||Replacement||25%||435||200||>1,000|
|Surface or low||51%||210||50||250|
|Mixed mesophytic hardwood||Replacement||11%||665|
|Surface or low||79%||90|
|Surface or low||89%||6||3||10|
|Eastern hemlock-eastern white pine-hardwood||Replacement||17%||>1,000||500||>1,000|
|Surface or low||83%||210||100||>1,000|
|Oak (eastern dry-xeric)||Replacement||6%||128||50||100|
|Surface or low||78%||10||1||10|
|Appalachian oak forest (dry-mesic)||Replacement||6%||220|
|Surface or low||79%||17|
|Vegetation Community (Potential Natural Vegetation Group)||Fire severity*||Fire regime characteristics|
|Percent of fires||Mean interval
|Southeast Gulf Coastal Plain Blackland prairie and woodland||Replacement||22%||7|
|Surface or low||97%||4||1||5|
|Longleaf pine (mesic uplands)||Replacement||3%||110||40||200|
|Surface or low||97%||3||1||5|
|Longleaf pine-Sandhills prairie||Replacement||3%||130||25||500|
|Surface or low||97%||4||1||10|
|Surface or low||10%||43||2||50|
|South Florida slash pine flatwoods||Replacement||6%||50||50||90|
|Surface or low||94%||3||1||6|
|Atlantic wet pine savanna||Replacement||4%||100|
|Surface or low||94%||4|
|Coastal Plain pine-oak-hickory||Replacement||4%||200|
|Surface or low||89%||8|
|Atlantic white-cedar forest||Replacement||34%||200||25||350|
|Surface or low||59%||115||10||500|
|Surface or low||80%||9||3||50|
|Surface or low||97%||2||1||8|
|Loess bluff and plain forest||Replacement||7%||476|
|Surface or low||85%||39|
|Surface or low||93%||63|
Replacement: Any fire that causes greater than 75% top removal of a vegetation-fuel type, resulting in general replacement of existing vegetation; may or may not cause a lethal effect on the plants.
Mixed: Any fire burning more than 5% of an area that does not qualify as a replacement, surface, or low-severity fire; includes mosaic and other fires that are intermediate in effects.
Surface or low: Any fire that causes less than 25% upper layer replacement and/or removal in a vegetation-fuel class but burns 5% or more of the area [55,91].
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108. Miller, Donald Ray. 1957. Soil types and earthworm abundance in woodcock habitat in central Pennsylvania. University Park, PA: Pennsylvania State University. 70 p. Thesis. 
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