Index of Species Information

WILDLIFE SPECIES:  Buteo lagopus


Introductory

WILDLIFE SPECIES: Buteo lagopus
AUTHORSHIP AND CITATION : Sullivan, Janet. 1995. Buteo lagopus. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ [].

ABBREVIATION : BULA COMMON NAMES : rough-legged hawk American roughleg TAXONOMY : The accepted scientific name of the rough-legged hawk is Buteo lagopus (Pontoppidan) [32]. The American subspecies is B. l. sanctijohannis (Gmelin). Some authors include B. l. kamtschatkensis Dementiev (Siberian roughleg) in occurrences of rough-legged hawks in northwestern Alaska [1]; a different interpretation treats these as intermediate between B. l. sanctijohannis and kamtschatkensis and places them with sanctijohannis [28]. The type subspecies, B. l. lagopus (rough-legged buzzard), is found only in Eurasia [1,28,37]. ORDER : Falconiformes CLASS : Bird FEDERAL LEGAL STATUS : No special status OTHER STATUS : NO-ENTRY


WILDLIFE DISTRIBUTION AND OCCURRENCE

WILDLIFE SPECIES: Buteo lagopus
GENERAL DISTRIBUTION : The breeding range of rough-legged hawk encompasses the high arctic regions of the United States and Canada. The rough-legged hawk breeds from western and northern Alaska, northern Yukon Territory, and northern Labrador south to northern and southeastern MacKenzie District, central Canada, and northern Quebec and Newfoundland. It also breeds from the Kodiak islands and Umnak north to Prince Patrick, Victoria, Bylot, and southwestern Baffin islands (Northwest Territories) [11,12,28,34]. The rough-legged hawk winters from south-central Alaska (casual) and southern Canada south to southern California and southern Arizona, and east to southern Texas, Missouri, Tennessee, and Virginia. On the East Coast wintering rough-legged hawks occur from Cape Cod to Chesapeake Bay and are occasionally observed in eastern Texas and on the Gulf Coast [11,22,28]. ECOSYSTEMS : FRES10 White-red-jack pine FRES11 Spruce-fir FRES15 Oak-hickory FRES17 Elm-ash-cottonwood FRES18 Maple-beech-birch FRES19 Aspen-birch FRES20 Douglas-fir FRES21 Ponderosa pine FRES22 Western white pine FRES23 Fir-spruce FRES24 Hemlock-Sitka spruce FRES25 Larch FRES26 Lodgepole pine FRES27 Redwood FRES28 Western hardwoods FRES29 Sagebrush FRES30 Desert shrub FRES31 Shinnery FRES32 Texas savanna FRES33 Southwestern shrubsteppe FRES34 Chaparral-mountain shrub FRES35 Pinyon-juniper FRES36 Mountain grasslands FRES37 Mountain meadows FRES38 Plains grasslands FRES39 Prairie FRES40 Desert grasslands FRES41 Wet grasslands FRES42 Annual grasslands STATES :
AK AZ AR CA CO CT DE ID IL
IN IA KS KY LA ME MD MA MI
MN MS MO MT NE NV NH NJ NM
NY NC ND OH OK OR PA RI SC
SD TN TX UT VT VA WA WV WI WY

AB BC MB NB NF NT NS ON PE PQ
SK YT
BLM PHYSIOGRAPHIC REGIONS : 1 Northern Pacific Border 2 Cascade Mountains 3 Southern Pacific Border 4 Sierra Mountains 5 Columbia Plateau 6 Upper Basin and Range 7 Lower Basin and Range 8 Northern Rocky Mountains 9 Middle Rocky Mountains 10 Wyoming Basin 11 Southern Rocky Mountains 12 Colorado Plateau 13 Rocky Mountain Piedmont 14 Great Plains 15 Black Hills Uplift 16 Upper Missouri Basin and Broken Lands KUCHLER PLANT ASSOCIATIONS : K002 Cedar-hemlock-Douglas-fir forest K003 Silver fir-Douglas-fir forest K004 Fir-hemlock forest K005 Mixed conifer forest K009 Pine-cypress forest K010 Ponderosa shrub forest K011 Western ponderosa forest K012 Douglas-fir forest K015 Western spruce-fir forest K016 Eastern ponderosa forest K017 Black Hills pine forest K018 Pine-Douglas-fir forest K019 Arizona pine forest K020 Spruce-fir-Douglas-fir forest K021 Southwestern spruce-fir forest K022 Great Basin pine forest K024 Juniper steppe woodland K027 Mesquite bosque K028 Mosaic of K002 and K026 K029 California mixed evergreen forest K031 Oak-juniper woodlands K032 Transition between K031 and K037 K033 Chaparral K034 Montane chaparral K037 Mountain-mahogany-oak scrub K038 Great Basin sagebrush K039 Blackbrush K040 Saltbush-greasewood K041 Creosotebush K042 Creosotebush-bursage K043 Paloverde-cactus shrub K044 Creosotebush-tarbush K045 Ceniza shrub K055 Sagebrush steppe K056 Wheatgrass-needlegrass shrubsteppe K058 Grama-tobosa shrubsteppe K059 Trans-Pecos shrub savanna K060 Mesquite savanna K061 Mesquite-acacia savanna K062 Mesquite-live oak savanna K071 Shinnery K081 Oak savanna K082 Mosaic of K074 and K100 K084 Cross Timbers K086 Juniper-oak savanna K087 Mesquite-oak savanna K089 Black Belt K093 Great Lakes spruce-fir forest K094 Conifer bog K095 Great Lakes pine forest K096 Northeastern spruce-fir forest K097 Southeastern spruce-fir forest K098 Northern floodplain forest K101 Elm-ash forest K106 Northern hardwoods K107 Northern hardwoods-fir forest K108 Northern hardwoods-spruce forest K109 Transition between K104 and K106 SAF COVER TYPES : 1 Jack pine 5 Balsam fir 21 Eastern white pine 22 White pine-hemlock 23 Eastern hemlock 24 Hemlock-yellow birch 35 Paper birch-red spruce-balsam fir 37 Northern white-cedar 51 White pine-chestnut oak 63 Cottonwood 95 Black willow 107 White spruce 201 White spruce 202 White spruce-paper birch 204 Black spruce 205 Mountain hemlock 206 Engelmann spruce-subalpine fir 207 Red fir 208 Whitebark pine 209 Bristlecone pine 212 Western larch 213 Grand fir 215 Western white pine 218 Lodgepole pine 219 Limber pine 220 Rocky Mountain juniper 223 Sitka spruce 224 Western hemlock 225 Western hemlock-Sitka spruce 226 Coastal true fir-hemlock 227 Western redcedar-western hemlock 228 Western redcedar 229 Pacific Douglas-fir 230 Douglas-fir-western hemlock 231 Port-Orford-cedar 234 Douglas-fir-tanoak-Pacific madrone 237 Interior ponderosa pine 238 Western juniper 243 Sierra Nevada mixed conifer 244 Pacific ponderosa pine-Douglas-fir 245 Pacific ponderosa pine 251 White spruce-aspen 253 Black spruce-white spruce 254 Black spruce-paper birch 256 California mixed subalpine SRM (RANGELAND) COVER TYPES : 101 Bluebunch wheatgrass 102 Idaho fescue 103 Green fescue 104 Antelope bitterbrush-bluebunch wheatgrass 105 Antelope bitterbrush-Idaho fescue 106 Bluegrass scabland 107 Western juniper/big sagebrush/bluebunch wheatgrass 109 Ponderosa pine shrubland 110 Ponderosa pine-grassland 201 Blue oak woodland 203 Riparian woodland 206 Chamise chaparral 207 Scrub oak mixed chaparral 208 Ceanothus mixed chaparral 209 Montane shrubland 210 Bitterbrush 211 Creosotebush scrub 212 Blackbush 301 Bluebunch wheatgrass-blue grama 302 Bluebunch wheatgrass-Sandberg bluegrass 303 Bluebunch wheatgrass-western wheatgrass 304 Idaho fescue-bluebunch wheatgrass 305 Idaho fescue-Richardson needlegrass 306 Idaho fescue-slender wheatgrass 307 Idaho fescue-threadleaf sedge 309 Idaho fescue-western wheatgrass 310 Needle-and-thread-blue grama 311 Rough fescue-bluebunch wheatgrass 312 Rough fescue-Idaho fescue 314 Big sagebrush-bluebunch wheatgrass 315 Big sagebrush-Idaho fescue 316 Big sagebrush-rough fescue 317 Bitterbrush-bluebunch wheatgrass 318 Bitterbrush-Idaho fescue 319 Bitterbrush-rough fescue 320 Black sagebrush-bluebunch wheatgrass 321 Black sagebrush-Idaho fescue 322 Curlleaf mountain-mahogany-bluebunch wheatgrass 323 Shrubby cinquefoil-rough fescue 324 Threetip sagebrush-Idaho fescue 401 Basin big sagebrush 402 Mountain big sagebrush 403 Wyoming big sagebrush 404 Threetip sagebrush 405 Black sagebrush 406 Low sagebrush 407 Stiff sagebrush 408 Other sagebrush types 409 Tall forb 411 Aspen woodland 412 Juniper-pinyon woodland 413 Gambel oak 414 Salt desert shrub 415 Curlleaf mountain-mahogany 416 True mountain-mahogany 417 Littleleaf mountain-mahogany 418 Bigtooth maple 419 Bittercherry 420 Snowbrush 421 Chokecherry-serviceberry-rose 422 Riparian 501 Saltbush-greasewood 502 Grama-galleta 503 Arizona chaparral 504 Juniper-pinyon pine woodland 505 Grama-tobosa shrub 506 Creosotebush-bursage 507 Palo verde-cactus 508 Creosotebush-tarbush 509 Transition between oak-juniper woodland and mahogany-oak association 601 Bluestem prairie 602 Bluestem-prairie sandreed 603 Prairie sandreed-needlegrass 604 Bluestem-grama prairie 605 Sandsage prairie 606 Wheatgrass-bluestem-needlegrass 607 Wheatgrass-needlegrass 608 Wheatgrass-grama-needlegrass 609 Wheatgrass-grama 610 Wheatgrass 611 Blue grama-buffalograss 612 Sagebrush-grass 614 Crested wheatgrass 615 Wheatgrass-saltgrass-grama 701 Alkali sacaton-tobosagrass 702 Black grama-alkali sacaton 703 Black grama-sideoats grama 704 Blue grama-western wheatgrass 705 Blue grama-galleta 706 Blue grama-sideoats grama 707 Blue grama-sideoats grama-black grama 708 Bluestem-dropseed 709 Bluestem-grama 710 Bluestem prairie 712 Galleta-alkali sacaton 713 Grama-muhly-threeawn 714 Grama-bluestem 715 Grama-buffalograss 716 Grama-feathergrass 717 Little bluestem-Indiangrass-Texas wintergrass 718 Mesquite-grama 719 Mesquite-liveoak-seacoast bluestem 720 Sand bluestem-little bluestem (dunes) 721 Sand bluestem-little bluestem (plains) 722 Sand sagebrush-mixed prairie 724 Sideoats grama-New Mexico feathergrass-winterfat 725 Vine mesquite-alkali sacaton 727 Mesquite-buffalograss 728 Mesquite-granjeno-acacia 729 Mesquite 730 Sand shinnery oak 731 Cross timbers-Oklahoma 732 Cross timbers-Texas (little bluestem-post oak) 733 Juniper-oak 734 Mesquite-oak 801 Savanna 802 Missouri prairie 803 Missouri glades 804 Tall fescue 805 Riparian 806 Gulf Coast salt marsh 807 Gulf Coast fresh marsh 809 Mixed hardwood and pine 819 Freshwater marsh and ponds 822 Slough PLANT COMMUNITIES : Breeding Habitat: The breeding habitat of rough-legged hawk is open tundra and mountains; the southern limit of its breeding range coincides with the latitudinal tree line [11,22]. Rough-legged hawks occasionally nest in trees at the edge of boreal forest [22]. The rough-legged hawk is not usually observed in forests, except where there is much open ground. Kochert [24] listed tundra and taiga as breeding habitat for the rough-legged hawk. Wintering Habitat: The rough-legged hawk prefers conifer groves for roosting and hunts in open, treeless areas [11]. Kochert [24] listed rough-legged hawk wintering habitat as open shrub and grassland in temperate areas. Rough-legged-hawks were observed wintering in pinyon (Pinus spp.)-juniper (Juniperus spp.) woodlands in the southwestern United States [4]. REFERENCES : NO-ENTRY

BIOLOGICAL DATA AND HABITAT REQUIREMENTS

WILDLIFE SPECIES: Buteo lagopus
TIMING OF MAJOR LIFE HISTORY EVENTS : Breeding: Age at first breeding is 2 to 3 years [22]. Rough-legged form pair bonds that are maintained for at least the duration of the breeding season and possibly longer. There is some evidence that pair bonding occurs in wintering areas; birds roost and perch in twos and sometimes migrate in twos [28]. After the loss of a mate, a new mate is usually acquired fairly rapidly [22]. There is usually only one brood per season [12]. Spring Migration: Rough-legged hawks travel in loose flocks; up to 10 birds may be seen at a time, though hundreds might pass a hawk station in a day. Rough-legged hawks are not averse to crossing wide bodies of water, which is unusual for a buteo. They migrate across boreal forest to find open country [28]. In the western part of rough-legged hawk range, spring migration begins in late March or early April, with the largest flights in late April. Breeding pairs arrive on the breeding grounds in late April to early May [37]. In the eastern part of its range, rough-legged hawk migration occurs from early March to late April or the first week of May; the peak period is in late March [20]. Nest: The nest is constructed of sticks, bones, other debris, weeds, and grass, and is lined with grass, down, feathers, and the fur of prey animals [12]. Nests tend to be larger in areas where more sticks are available. Typical nests range in size from 24 to 30 inches (61-76 cm) across and 20 to 22 inches (50-55 cm) deep [37]. Nests are used repeatedly and become larger as new material is added [22]. Clutch: Eggs have been observed in rough-legged hawk nests from May to June, sometimes as late as July [34]. Earliest egg dates were May 2 in Labrador and May 18 in arctic Canada and Alaska. Latest egg dates were June 23 in Labrador and July 13 in arctic Canada and Alaska [28]. In captivity eggs are laid at 2-day intervals; on average, clutches of five eggs take 10 days to lay [22]. Clutch size is variable and ranges from two to seven eggs; clutches are smaller when prey is scarce [12]. Clutches of five to seven eggs are common in good lemming (Lemmus and Dicrostonyx spp.) years; clutches of two or three eggs are more common in poor lemming years [22]. Incubation: Eggs are incubated for 28 to 31 days, mostly by the female. The male feeds her, guards the nest, and incubates the eggs for only short periods [28,37]. Eggs hatch asynchronously [12]. Development of Young: Rough-legged hawk chicks are semialtricial; at hatching they are immobile and downy with eyes open. They are fed by both parents. Age of first flight is usually between 36 and 40 days [12]. Most rough-legged hawk young leave the nest in early July to mid-August at approximately 6 weeks of age but continue to depend on the parents for food for a short period thereafter [37]. Dependence on the parents for food sometimes extends to fall migration [28]. Fall Migration: There is usually no large and distinct peak for autumnal rough-legged hawk flights as there is in the spring [20]. At a hawk-watching station on the shore of Lake Superior, peak flights of migrating rough-legged hawks occurred from October 13 through the 31st. The rough-legged hawk arrives in wintering areas in September and October, and is settled from November through March [22]. Longevity: The average life span of the rough-legged hawk is 20.7 months [28]. Rough-legged hawks have been reported as old as 6 years 9 months [34] and 18 years 1 month [28]. Population Fluctuations: There are wide fluctuations in local winter populations of rough-legged hawk in the southwestern United States [4]. Localized nonseasonal migrations of rough-legged hawk occur when prey populations crash in usual breeding areas and the hawks move to areas of more abundant prey [12]. Diurnal Patterns in Winter: Most rough-legged hawks are active during sunlight hours and retire to night perches by 4:30 p.m. [28]. Peak activity is usually observed during periods of high wind velocity, clear sky, rising air pressure, low relative humidity and high temperature [37]. Diurnal Patterns in Summer: In Finland, rough-legged buzzards were observed active by 4 a.m. in June and July. They remained active throughout the day until 8 p.m. (sometimes as late as 10 p.m.) [29]. Rough-legged hawks have occasionally been observed hunting between 12 a.m. and 3 a.m. in arctic Alaska [37]. PREFERRED HABITAT : Nesting: Rough-legged hawk nests are usually built on cliffs, river bluffs, rocky outcroppings and ledges, columnar rocks, artificial structures such as cairns, on the ground on steep hillsides, and rarely, in trees [11,22,28]. Sites with an overhanging ledge or caprock are preferred [22]. There appears to be a tendency to nest in clusters of breeding pairs; however, this may be a function of nest site availability [28]. Estimated average breeding density is approximately one pair per 3.1 square miles (7.8 sq km). Highest recorded density was one pair per 1.6 square miles (4 sq km); however, there is often only one pair per 31.2 square miles (78 sq km) [8]. Near the Colville River, Alaska, nests averaged 2.3 linear miles (3.8 km) apart, ranging from 0.24 to 13.2 miles (0.4-22 km) apart. Rough-legged hawks usually return to the same nest site from year to year, even in the face of heavy competition from peregrine falcons (Falco peregrinus) or gyrfalcons (F. rusticolus) for the same site [22]. Rough-legged hawks are not as aggressive as the late-migrating peregrine falcons, which often displace rough-legged hawks from nest sites [22,28]. Hunting: The rough-legged hawk prefers to hunt in open areas: wet meadows, bogs, marshes, riparian areas, pastures, and shrub-grass uplands [4,24]. Hunting territory size during the breeding season is variable; it may be as small as 2 to 2.4 square miles (5-6 sq km) when prey density is high [22]. Wintering: Rough-legged hawks usually winter in open country: farmlands [32], plains, prairies, airports and other open urban areas, coastal marshes, and agricultural lands. The winter home range usually ranges from 4 to 6 square miles (10-15 sq km) [22]. Competition where winter ranges overlap those of the red-tailed hawk (Buteo jamaicensis) is mitigated by behavioral differences in hunting styles; for example, rough-legged hawks hunt from lower perches, prefer more open areas, and avoid snow cover more than red-tailed hawks do [37]. The rough-legged hawk is absent from northern regions where the average minimum January temperature is less than -10 degrees Fahrenheit (-23 deg C). This hawk tends to avoid the western coastline and the southeastern corner of the United States. It is most abundant in areas with less than 40 inches (1,020 mm) annual precipitation [28]. COVER REQUIREMENTS : Nest sites appear to be selected at least partly for a wide view [22,29] FOOD HABITS : During the breeding season, the rough-legged hawk preys primarily on microtine rodents (Microtus and Peromyscus spp.), brown lemming (Lemmus sibericus), Nelson's collared lemming (Dicrostonyx groenlandicus), tundra vole (M. oeconomus), singing vole (M. miurus), northern red-backed vole (Cleithrionomys rutilis), and other small mammals [4]. Lemmings may comprise 80 to 85 percent of the summer diet [28]. In the Northwest Territories brown lemmings comprised 83 percent of rough-legged hawk summer diet, with lesser amounts of collared lemming and arctic ground squirrel (Spermophilus parryi) [37], and occassionally, Alaska hare (Lepus othus) [28]. Other food items include insects and carrion [12]. Rough-legged hawks have been observed consuming ringed seal (Phoca hispida) and caribou (Rangifer tarandus) carcasses [39]. Springer reported that up to 30 percent of breeding season diet in Alaska was avian prey, and consisted mostly of fledgling passerines, ptarmigan (Lagopus spp.), and occasionally lesser golden-plover (Pluvialis dominica) [33]. Palmer and Mindell [28] reported that avian prey of rough-legged hawks in Alaska included grouse (probably spruce grouse [Dendrapagus canadensis]) chicks, shorebirds, lesser golden-plover, red-necked phalarope (Phalaropus lobatus), whimbrel (Numenius phaeopus) chicks and juveniles, and other small birds such as wagtail (Motacilla spp.), American tree sparrow (Spizella arborea), Lapland longspur (Calcarius lapponicus), and snow bunting (Plectrophenax nivalis) [28]. Winter diet is almost exclusively small mammals [4]. Palmer and Mindell [28] estimated that voles comprise up to 80 or 90 percent of the winter diet of rough-legged hawks, but occasionally birds as large as ring-necked pheasant (Phasianus colchicus) and gray partridge (Perdix perdix) may be taken [22]. On occasion weasels (Mustela spp.), ground squirrels (Spermophilus spp.), rats (Rattus spp.), house mouse (Mus musculus), and shrews (Crystotis, Sorex, and Blarina spp.) are eaten [28]. In Iowa, wintering rough-legged hawks consumed meadow vole (Microtus pennsylvanicus), western harvest mouse (Reithrodontomys megalotis), and occasionally eastern cottontail (Silvilagus floridanus). At another site in Iowa, deer mouse (Peromyscus maniculatus) and house mouse were important in winter diets [37]. Wintering rough-legged hawks have been observed fishing, and are also known to take frogs [28,37]. A rough-legged hawk was observed stealing prey from a northern harrier (Circus cyaneus), and rough-legged hawks were observed with other raptors as prey, including sharp-shinned hawk [Accipiter striatus]) [28] and short-eared owl (Asio flammeus) [27]. Hunting Style: Much hunting is done from perches, including relatively low sites such as fenceposts, poles, and even slightly elevated sites such as rocks or mounds [22]. The rough-legged hawk frequently hovers over one spot at an altitude of 50 to 132 feet (15-40 m) [28]. There is also an appreciable amount of low-altitude flap and glide hunting for mice; a rough-legged hawk often will quarter back and forth over open fields [28,34]. PREDATORS : Rough-legged hawks have few natural enemies. Terrestrial predators include arctic fox (Alopex lagopus) and red fox (Vulpes vulpes), but nests are usually so inaccessible and so well guarded as to preclude much nest predation by foxes. Gray wolves (Canis lupus) and golden eagles (Aquila chrysaetos) have been observed eating young rough-legged hawks in nests in Alaska [37]. MANAGEMENT CONSIDERATIONS : The rough-legged hawk is one of North America's most abundant raptors [12]. Although no historical data on rough-legged hawk populations are available, it is probable that the rough-legged hawk is currently stable in North America [36]. White and Cade [38] assert that rough-legged hawks are probably stable as a breeding population in Alaska, except where oil and gas drilling sites, roads, pipeline development, and other installations destroy nest habitat. The estimated North American winter population of rough-legged hawks was 49,600 based on 1986 Christmas bird count data [12]. The maximum winter densities of rough-legged hawk occurred in Montana and Idaho, with estimated state populations of 5,250 and 3,650 birds, respectively [22]. Several studies on the abundance of rough-legged hawks are available [3,6,15]. Conservation and management of the rough-legged hawk depends on factors affecting habitat in Canada and the United States [7]. Population sizes and local abundance of rough-legged hawk are strongly influenced by local prey populations [22]. Local rough-legged hawk populations have been observed to increase and decrease with rodent prey availability; local population size is apparently a function of hawk movement to areas with abundant prey (rather than an absolute increase or decrease). For example, on the Seward Peninsula, there were 35 nesting pairs of rough-legged hawks in 1968, 43 pairs in 1969, and 82 pairs in 1970; however, only 10 pairs were found and two young fledged in 1971 following a severe autumn in 1970 which held microtine populations low. In 1972, there were 44 nesting pairs [37]. In Norway high density of breeding pairs of rough-legged buzzards corresponded with high density of voles [19]. Palmer and Mindell [28], however, asserted that fluctuations in vole populations probably influence but are not the sole cause of rough-legged hawk population fluctuations since rough-legged hawks shift to other prey when voles are scarce. The degree to which rough-legged hawk breeding success is independent of vole population is related to the availability and use of alternate prey [28]. Microtine rodent population fluctuations appear to be random rather than cycling at 4-year or 10-year intervals, as has been previously asserted, which further complicates understanding of the relationship of rough-legged hawk populations to prey populations [18]. In Finland rough-legged buzzard nesting density was reported to be independent of small mammal stocks; good nesting success occurred even in poor vole years [29]. Winter rough-legged hawk populations are often concentrated in areas of high prey density [37]. At a hawk migration station on Lake Superior, rough-legged hawks were the most numerous raptor observed in 1979, even though 1979 was probably a low population year for rough-legged hawks [13]. Migration counts of rough-legged hawks at Bake Oven Knob, Pennsylvania, were variable, increasing and decreasing in what appeared to be 3- to 5-year cycles. Cycles were also reported for migration counts at Hawk Mountain, Maine [21]. In New Jersey wintering population densities of rough-legged hawks varied widely between years but showed no obvious upward or downward trend [7]. Rough-legged hawks banded in California bred in several locations, from Alaska to Banks Island in the Northwest Territories. Encounters with banded rough-legged hawks suggest that rough-legged hawks from the western part of the breeding range migrate to the western parts of the winter range. Rough-legged hawks also show strong fidelity to the same winter area in subsequent years; this suggests that the loss of wintering habitat to residential development could be detrimental to rough-legged hawk populations [16]. Wintering concentrations of rough-legged hawks in the Great Plains and the Intermountain West were correlated primarily with climate and the presence of protected areas such as wildlife refuges. The rough-legged hawk is most common in the Great Basin and the Northern Great Plains. Winter populations are high in Montana, northern Oregon, southern Washington, and northeastern Maine north to Newfoundland [30]. A drive-by survey in southeastern Idaho revealed that rough-legged hawks were the most abundant raptor, appearing most often on agricultural land [10]. Wintering rough-legged hawks are widely distributed throughout New Jersey, but appear to prefer coastal areas. Abundance in New Jersey was significantly correlated (p < 0.002) with wetlands; rough-legged hawks also appear to avoid areas with snow cover [7]. Mortality Factors: The rough-legged hawk is often relatively unsuspicious of human approach. Prior to their legal protection, rough-legged hawks were shot in large numbers in wintering areas of the United States or were caught in pole traps. In Utah large numbers of migrant rough-legged hawks were reported killed by cars while feeding on road-killed jackrabbits (Lepus spp.) [35,37]. In 1967 mortality from dieldrin poisoning was documented in rough-legged buzzards in Britain. Consumption of only a few animals that had eaten dieldrin-treated grain was sufficient to kill the hawks [37]. REFERENCES : NO-ENTRY

FIRE EFFECTS AND USE

WILDLIFE SPECIES: Buteo lagopus
DIRECT FIRE EFFECTS ON ANIMALS : There are no reported mortalities of rough-legged hawks from fire in the literature. It is likely that fire mortality of raptors is confined to nestlings [26]; the placement of most rough-legged hawk nests makes this very unlikely. HABITAT RELATED FIRE EFFECTS : There has only been one review of the relationship between raptor habitat and fire and no specific information was available for rough-legged hawk [36]. Fire Effects on Prey Species: Fire usually causes temporary declines in populations. Vegetation recovery after fire usually increases available vegetative biomass. Small mammal population declines are compensated for in 1 or 2 years [23]. In a study of the effects of vegetation manipulation on small mammal populations, Cornely and others [9] compared burned plots to untreated plots and plots that had been mowed. Montane vole (Microtus montanus) populations were low immediately following a November 1978 prescribed fire, but were higher than any other treatments on burned plots in January 1980. Immediately after burning, rodent populations were lower on burned plots than on untreated plots [9]. Open habitats that are frequented by rough-legged hawks and dependent on fire include grassland, semidesert grass-shrub, and sagebrush (Artemisia spp.)-grassland. Grasslands are maintained by frequent fire (1- to 10-year average fire return intervals). Fire exclusion in the deciduous forest-prairie ecotone has reduced available rough-legged hawk winter habitat. Increased shrub densities have occurred in the last 80 years in semidesert grass-shrub habitats. These habitats typically have average fire-free intervals of 10 years; the causal mechanism for the increase in shrub density is not well understood; primary causes are probably increased grazing, and increased fire intensity and frequency due to fire exclusion and cheatgrass (Bromus tectorum) invasion. Sagebrush-grass habitats, with fire-free intervals ranging from 20 to 100 years, have also been altered by cheatgrass invasion which probably has increased fire frequency [26]. FIRE USE : NO-ENTRY REFERENCES : NO-ENTRY

References for species: Buteo lagopus


1. American Ornithologists' Union. 1957. Checklist of North American birds. 5th ed. Baltimore, MD: The Lord Baltimore Press, Inc. 691 p. [21235]
2. American Ornithologists' Union. 1983. Checklist of North American birds. 6th ed. Lawrence, KS: Allen Press, Inc. 877 p. [21234]
3. Andersen, D. E.; Rongstad, O. J.; Mytton, W. R. 1985. Line transect analysis of raptor abundance along roads. Wildlife Society Bulletin. 13(4): 533-539. [24591]
4. Balda, Russell P.; Masters, Nancy. 1980. Avian communities in the pinyon-juniper woodland: a descriptive analysis. In: DeGraaf, Richard M., technical coordinator. Management of western forests and grasslands for nongame birds: Workshop proceedings; 1980 February 11-14; Salt Lake City, UT. Gen. Tech. Rep. INT-86. Ogden, UT: U.S. Department of Agriculture, Forest Service, Intermountain Forest and Range Experiment Station: 146-169. [17903]
5. Bernard, Stephen R.; Brown, Kenneth F. 1977. Distribution of mammals, reptiles, and amphibians by BLM physiographic regions and A.W. Kuchler's associations for the eleven western states. Tech. Note 301. Denver, CO: U.S. Department of the Interior, Bureau of Land Management. 169 p. [434]
6. Bildstein, Keith Louis. 1978. Behavioral ecology of red-tailed hawks (Buteo jamaicensis), rough-legged hawks (B. lagopus), and northern harriers (Circus cyaneus). Columbus, OH: Ohio State University. 364 p. Dissertation. [24993]
7. Bosakowski, Thomas; Smith, Dwight G. 1992. Demography of wintering rough-legged hawks in New Jersey. Journal of Raptor Research. 26(2): 61-65. [24445]
8. Brown, Leslie; Amadon, Dean. 1968. Eagles, hawks and falcons of the world. Vol. 2. New York: McGraw-Hill Book Company. 945 p. [22970]
9. Cornely, J. E.; Britton, C. M.; Sneva, F. A. 1983. Manipulation of flood meadow vegetation and observations on small mammal populations. Prairie Naturalist. 15: 16-22. [14509]
10. Craig, Timothy H. 1978. A car survey of raptors in southeastern Idaho 1974-1976. Raptor Research. 12(1/2): 40-45. [24444]
11. DeGraaf, Richard M.; Scott, Virgil E.; Hamre, R. H.; [and others]. 1991. Forest and rangeland birds of the United States: Natural history and habitat use. Agric. Handb. 688. Washington, DC: U.S. Department of Agriculture, Forest Service. 625 p. [15856]
12. Ehrlich, Paul R.; Dobkin, David S.; Wheye, Darryl. 1988. The birder's handbook: a field guide to the natural history of North American birds. New York: Simon & Schuster, Inc. 785 p. [21559]
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