Index of Species Information

WILDLIFE SPECIES:  Buteo swainsoni

Introductory

WILDLIFE SPECIES: Buteo swainsoni
AUTHORSHIP AND CITATION : Tesky, Julie L. 1994. Buteo swainsoni. 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 : BUSW COMMON NAMES : Swainson's hawk TAXONOMY : The currently accepted scientific name for the Swainson's hawk is Buteo swainsoni Bonaparte [1]. There are no recognized subspecies or races. ORDER : Falconiformes CLASS : Bird FEDERAL LEGAL STATUS : Not listed [43] OTHER STATUS : Information on state-level protected status of animals in the United States and Canada is available at NatureServe.


WILDLIFE DISTRIBUTION AND OCCURRENCE

WILDLIFE SPECIES: Buteo swainsoni
GENERAL DISTRIBUTION : The breeding range of the Swainson's hawk is restricted primarily to western North America from interior Alaska and western Canada south into northern Mexico [12,21].  The Swainson's hawk winters primarily on the pampas of southern South America, irregularly north to Costa Rica and Panama, and sometimes north to the southwestern United States and southern Florida [1,12,21].  During migration the Swainson's hawk occurs regularly in most of the central states and Canadian provinces, and rarely, east along the Gulf Coast to Florida. It is occasionally a fall migrant through the Florida Keys.  The Swainson's hawk is occasionally found in northeastern North America from southern Ontario, southern Quebec, New York, and Massachusetts south to Virginia [1]. ECOSYSTEMS : FRES28 Western hardwoods FRES29 Sagebrush FRES30 Desert shrub FRES31 Shinnery 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 CA CO CT DE FL ID IL
IA KS LA MD MA MT NE NV NH
NJ NM NY ND OH OK OR PA RI
SD TN TX UT VA WA WY

AB BC MB NT ON PQ SK YT
MEXICO
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 :    K023  Juniper - pinyon woodland    K024  Juniper steppe woodland    K026  Oregon oakwoods    K027  Mesquite bosque    K030  California oakwoods    K031  Oak - juniper woodlands    K032  Transition between K031 and K037    K033  Chaparral    K034  Montane chaparral    K035  Coastal sagebrush    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    K047  Fescue - oatgrass    K048  California steppe    K050  Fescue - wheatgrass    K051  Wheatgrass - bluegrass    K053  Grama - galleta steppe    K054  Grama - tobosa prairie    K055  Sagebrush steppe    K056  Wheatgrass - needlegrass shrubsteppe    K057  Galleta - three-awn shrubsteppe    K058  Grama - tobosa shrubsteppe    K059  Trans-Pecos shrub savanna    K060  Mesquite savanna    K061  Mesquite - acacia savanna    K062  Mesquite - live oak savanna    K063  Foothills prairie    K064  Grama - needlegrass - wheatgrass    K065  Grama - buffalograss    K066  Wheatgrass - needlegrass    K067  Wheatgrass - bluestem - needlegrass    K068  Wheatgrass - grama - buffalograss    K069  Bluestem - grama prairie    K070  Sandsage - bluestem prairie    K071  Shinnery    K072  Sea oats prairie    K074  Bluestem prairie    K075  Nebraska Sandhills prairie    K076  Blackland prairie    K077  Bluestem - sacahuista prairie    K083  Cedar glades    K085  Mesquite - buffalograss    K086  Juniper - oak savanna    K087  Mesquite - oak savanna    K088  Fayette prairie SAF COVER TYPES :     66  Ashe juniper - redberry (Pinchot) juniper     67  Mohrs (shin) oak     68  Mesquite    203  Balsam poplar    217  Aspen    220  Rocky Mountain juniper    221  Red alder    222  Black cottonwood - willow    233  Oregon white oak    235  Cottonwood - willow    236  Bur oak    238  Western juniper    239  Pinyon - juniper    240  Arizona cypress    241  Western live oak    242  Mesquite    246  California black oak    249  Canyon live oak    250  Blue oak - Digger pine    252  Paper birch    255  California coast live oak SRM (RANGELAND) COVER TYPES : NO-ENTRY PLANT COMMUNITIES : The Swainson's hawk breeds in open grasslands, sagebrush (Artemisia spp.), shrub-steppe, oak (Quercus spp.) woodlands, open pine (Pinus spp.)-oak woodlands, pinyon-juniper (Pinus spp.-Juniperus spp.) woodlands, and cultivated lands [1,3,6,16,40].  In California the Swainson's hawk favors open blue oak (Quercus douglasii) savannahs and gray pine (Pinus sabiniana)-oak woodlands [35].  In the Central Valley of California, populations of Swainson's hawks frequently nest and roost in riparian communities dominated by valley oak (Quercus lobata), cottonwoods (Populus spp.), California sycamore (Platanus racemosa), and willows (Salix spp.)  [22,33].  Foraging habitat for Swainson's hawks in California includes native grassland communities of oat (Avena spp.), brome grass (Bromus spp.), ryegrass (Elymus spp. and Lolium spp.), and barley (Critesion spp.) [33]. West of Laramie, Wyoming, Dunkle [15] reported that breeding habitat of the Swainson's hawk included irrigated sedge meadows, shortgrass plains with some sagebrush, and black greasewood (Sarcobatus vermiculatus) [15]. In the Great Basin, the Swainson's hawk is often found nesting in juniper-sagebrush and prairie habitats [33].  In Arizona, the Swainson's hawk generally occurs in sparse semidesert grasslands, plains grasslands, Great Basin grasslands, and Chihuahuan Desert scrub often mixed with a few species of shrubs including yucca (Yucca spp.), creosotebush (Larrea tridentata), mesquite (Prosopis spp.), and fourwing saltbrush (Atriplex canescens).  In New Mexico and Texas, breeding Swainson's hawk occur in various types of grasslands including grasslands with sand shinnery oak (Q. havardii), and are occasionally found in Chihuahuan Desert scrub.  In Oklahoma, Swainson's hawk breed primarily in grasslands [6]. The Swainson's hawk sometimes nests in intensively cultivated areas [4,5,20].  Of the large raptors breeding in northern Colorado, only the Swainson's hawk regularly nested near cultivated lands [20].

BIOLOGICAL DATA AND HABITAT REQUIREMENTS

WILDLIFE SPECIES: Buteo swainsoni
TIMING OF MAJOR LIFE HISTORY EVENTS : Age at sexual maturity - Swainson's hawk are generally sexually mature at 2 years of age [31]. Nesting season - The Swainson's hawk arrives on its breeding grounds later than most raptors [31].  The nesting season generally occurs from March to October depending on geographic area [14,21,35].  In California, the Swainson's hawk breeds from late March to mid-August, with peak activity from late May to late July.  In Nevada, it breeds from April to October [21].  In Montana, the breeding season is from May to September [14].   Clutch size and incubation - The Swainson's hawk lays two to four eggs, with two most common [14,21,31,35].  The eggs are incubated for 28 to 35 days [14,21,31].  The Swainson's hawk may lay a replacement clutch if the first clutch is destroyed [31]. Fledging - Nestlings fledge in 35 to 44 days [21,31].  Fledglings continue to be fed by the adults and remain within the nesting territory for 14 to 21 days after fledging; they often return to the nest tree to roost [21]. Migration - The Swainson's hawk travels in large flocks (sometimes containing over 100 individuals) from the nesting areas south to their winter grounds in South America [6,21,31]. Peak fall migration clears the southern plains states and southern Texas by early October.  The Swainson's hawk arrives in Central America the last 3 weeks of October to early November; arrival in Argentina is reported as late November.  Average dates for spring migration of the Swainson's hawk are mid-March in Panama, the last 3 week of March in Costa Rica, the last half of March and first week of April in the state of Veracruz, Mexico, and early April in southern Texas [31]. Longevity - The Swainson's hawk probably seldom lives longer than 16 years [31]. PREFERRED HABITAT : The Swainson's hawk inhabits mostly semiopen to open areas in tundra, valleys, plains, dry meadows, foothills, and level uplands at low to middle elevations [1,31,40]. Nesting habitat - The Swainson's hawk nests almost exclusively in trees [37] and will nest in almost any tree species of suitable size (taller than 10 feet [3 m] with a d.b.h. of 2 inches [5 cm] or more) [6,7]. Nests are constructed in isolated trees (dead or live), in trees in wetlands and along drainages, or in windbreaks in fields and around farmsteads [6,12,31].  The Swainson's hawk builds nests from 4 to 100 feet (1.2-30.4 m) above the ground [12,14,35].  They sometimes add to an existing black-billed magpie (Pica pica) nest [31].  The Swainson's hawk occasionally nests in shrubs, on the crossbars of telephone poles, or on the ground, low cliffs, rocky pinnacles, or cutbanks [6,12,31]. In the Central Valley of California, the majority of Swainson's hawk nests and territories are located in or near riparian systems.  Nests are found most often in cottonwoods and oaks [33].  In Whitman County, Washington, Swainson's hawk nests were constructed in black locust (Robinia pseudoacacia), cherry (Prunus spp.) and hawthorn (Crataegus spp.) trees [5].  Of 48 Swainson's hawk nests on the Laramie Plains, Wyoming, 43 were in narrowleaf cottonwood (Populus angustifolia), peachleaf willow (Salix amygdaloides), or other willows.  None of the few buttes in the area were used for nesting [15].  In the Centennial Valley of Montana, Swainson's hawks nest extensively in willows [32]. At 234 Swainson's hawk nest sites in North Dakota, eastern cottonwood (Populus deltoides) was the most common tree species used (45%).  Other species included Chinese elm (Ulmus parvifolia), 22 percent; peachleaf willow, 13 percent; boxelder (Acer negundo), 12 percent; and green ash (Fraxinus pennsylvanica), 7 percent.  American elm (U. americana) and Russian olive (Elaeagnus angustifolia) accounted for the remaining 1 percent [20].  In the Lower Sonoran Desert of New Mexico, the Swainson's hawk often nests and roosts on large yucca plants [30].  In the southwestern United States, mesquite is commonly used [6]. Foraging habitat - The Swainson's hawk generally forages in open habitats with short vegetation containing small mammals, reptiles, birds, and insects [6,40,38].  During the nesting season the Swainson's hawk usually forages within 1.9 miles (3 km) of the nest.  The Swainson's hawk has a home range of approximately 3.5 square miles (9 sq km) [40].  Although the Swainson's hawk does search for prey from elevated perches, it relies much more on aerial foraging.  Consequently, it is not tied to habitats containing an abundance of perches, and often occupy habitats with few or no perches except the nest tree [23]. Winter habitat - The Swainson's hawk generally spends the winter south of the United States [1,12,31]; no information is available in the English literature on its habitat in Central and South America. COVER REQUIREMENTS : Swainson's hawk nests are often built in trees that provide shade for the nest but also afford a good view of the surrounding terrain [33]. The Swainson's hawk is a more efficient predator in open areas than in areas with high vegetative cover [5].  Bechard [5] found that vegetative cover is more important than prey abundance in the selection of hunting sites by the Swainson's hawk.  In Whitman County, Washington, the Swainson's hawk foraged at sites where vegetative height and density had been reduced, even though other areas had higher prey density [5]. Alfalfa field use by Swainson's hawk in northern California increased dramatically during monthly harvests that reduced vegetative heights [38]. FOOD HABITS : The Swainson's hawk is a versatile and opportunistic predator on relatively small prey [6].  The Swainson's hawk feeds on small mammals, large insects, birds, and reptiles [9,14,31,35].  During the breeding season, the Swainson's hawk primarily preys on small mammals, especially young ground squirrels (Spermophilus spp.), pocket gophers (Thomomys spp.), and some microtines [15,20,31,32].  During migration invertebrates often make up over 90 percent of the Swainson's hawk's diet [31]. In a North Dakota study, Swainson's hawks preyed primarily on northern pocket gopher (Thomomys talpoides), Richardson's ground squirrel (Spermophilus richardsonii), meadow vole (Microtus pennsylvanicus), and thirteen-lined ground squirrel (S. tridecemlineatus) [20].  To a lesser extent Swainson's hawks also ate western meadow lark (Sturnella neglecta), chestnut-collared longspur (Calcarius ornatus), sharp-tailed grouse (Tympanuchus phasianellus), short-eared owl (Asio flammeus), American kestrel (Falco sparverius), blue jay (Cyanocitta cristata), and rock dove (Columba livia) [20].  Toads (Bufo spp.) and various lizards, mostly desert grassland whiptail (Cnemidophorous uniparens) and spiny lizards (Sceloporus spp.), were commonly taken by nesting Swainson's hawk in Arizona.  Mammals, particularly cottontails (Sylvilagus spp.), ground squirrels, and kangaroo rats (Dipodomys spp.), were the most common food items brought to Swainson's hawk nestlings in New Mexico [6].  Rabbits comprised between 40 and 80 percent of the diet of Swainson's hawk nestlings in New Mexico [7]. PREDATORS : Large raptors including great horned owl (Buteo virginianus) and golden eagle (Aquila chrysaetos), and coyote (Canis latrans), bobcat (Lynx rufus), and striped skunk (Mephitis mephitis) have been known to kill Swainson's hawk nestlings and fledglings or destroy clutches [7,11,15,31,38].  Crows (Corvus spp.) sometimes destroy clutches [15,31]. MANAGEMENT CONSIDERATIONS : Swainson's hawk populations have declined over much of their breeding range due to habitat loss from cultivation, removal of riparian areas, and removal of shelterbelts [14,31].  Nest site availability may limit occurrence and breeding density of Swainson's hawk [6].  Schmutz and others [34] reported that the nesting density of the Swainson's hawk increased significantly following the erection of 98 artificial nest platforms in an experimental study plot.  When roads, pipelines, or other surface facilities are constructed, trees taller than 10 feet (3 m) with a d.b.h. of 2 inches (5 cm) or more should be conserved.  If destruction of potential nest trees cannot be avoided, they should be replaced with artificial nest platforms [7].  Within treeless expanses, constructing artificial nest platforms or planting trees may also benefit Swainson's hawk populations [6].  Additionally, establishing and enhancing small wooded areas in the nesting habitat, and protecting habitat used by the prey base, may benefit the Swainson's hawk [10,39]. The Swainson's hawk is more tolerant of human disturbance than other hawks and will often nest close to occupied houses [7,14].  However, intensive human activity in a small area near an active Swainson's hawk nest would likely result in nest abandonment and breeding failure at that site [7]. Swainson's hawk is sometimes eaten by people in South America.  Large numbers are taken from communal roosting areas and killed.  This activity could have a significant effect on populations that nest in North America [21].  Additionally, the use of biocides in North, Central, and South America may have an effect on Swainson's hawk populations.  The Swainson's hawk may accumulate high pesticide levels via food-chain concentration [31].

FIRE EFFECTS AND USE

WILDLIFE SPECIES: Buteo swainsoni
DIRECT FIRE EFFECTS ON ANIMALS : Fire directly reduces Swainson's hawk reproductive success if the fire crowns in occupied nest trees [25].  Fires that kill or otherwise alter unoccupied nest trees may disrupt reproduction if acceptable nest trees are scarce.  The Swainson's hawk arrives on breeding grounds comparatively late and so must establish or reestablish a nest site among earlier migrant and resident raptors [31].  Low-severity fires probably have little direct effect on Swainson's hawks.  Landers [25] commented that light winter burning probably does no substantial harm to raptors. HABITAT RELATED FIRE EFFECTS : The Swainson's hawk occurs in the following four major fire-dependent plant associations in the western United States:  grassland, semidesert grass-shrub, sagebrush grass, and pinyon-juniper [26]. Although fire may reduce potential nest trees, it may enhance the foraging habitat of Swainson's hawks.  Fires that reduce vegetation height and create open areas probably increase hunting efficiency by Swainson's hawks.  Open-habitat raptors such as the Swainson's hawk use scattered patches of woody vegetation near open foraging areas for nesting and perching.  However, where extensive invasion of woody species has occurred, Swainson's hawk foraging habitat may be reduced. The Swainson's hawk is favored by fires that reduce pinyon-juniper woodlands [26].  Raptors associated with pinyon-juniper woodlands depend upon edges of openings created by fire and scattered islands of unburned woodlands [13].  Fire suppression in pinyon-juniper habitats of the Great Basin of California may have reduced suitable Swainson's hawk habitat in this area [26]. Regular burning helps to maintain habitat for many prey species of Swainson's hawk [13,25].  Several studies indicate that many prey populations increase rapidly subsequent to burning in response to increased food availability [13].  Fire suppression in grasslands was detrimental to small bird and mammal populations due to organic matter accumulation and reduced plant vigor [36].  The Swainson's hawk has been observed hunting on recently burned areas in Colorado county, Texas [2]. On the Bridger Teton National Forest, Swainson's hawks were more commonly observed using a high-severity fall burn than a low-severity spring burn in the same area [27]. FIRE USE : Prescribed fire can be beneficial to Swainson's hawk populations by enhancing habitat and increasing the prey base [13,25].  Burning in grasslands where scattered trees are retained benefits Swainson's hawk populations, particularly in areas where nesting sites are limited. Prescribed burning plans should strive for creation of maximum interspersion of openings and edge, with high vegetative diversity. Habitats should be maintained in a random mosaic.  In most cases, burning plans must be integrated with proper range management. Reseeding of perennial grasses as well as rest from livestock grazing may be necessary to achieve desired goals.  Burning should be deferred until nesting is completed in areas where impact to breeding Swainson's hawk may occur [13]. An extensive body of research has been published on fire effects on animals in semidesert grassland, oak savanna, and Madrean oak woodlands of southeastern Arizona, including the response of Swainson's hawk to fire. See the Research Project Summary of this work for more information on Swainson's hawk and more than 100 additional species of birds, small mammals, grasshoppers, and herbaceous and woody plant species.

REFERENCES

WILDLIFE SPECIES: Buteo swainsoni
REFERENCES :  1.  American Ornithologists' Union. 1983. Checklist of North American birds.        6th ed. Lawrence, KS: Allen Press, Inc. 877 p.  [21234]  2.  Baker, R. H. 1940. Effects of burning and grazing on rodent populations.        Journal of Mammalogy. 21: 223.  [2849]  3.  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]  4.  Bechard, M. J. 1980. Factors affecting the productivity of Swainson's        hawk nesting in southeastern Washington. Pullman, WA: Washington State        University. [Pages unknown]. Dissertation.  [25334]  5.  Bechard, Marc J. 1982. Effect of vegetative cover on foraging site        selection by Swainson's hawk. Condor. 84(2): 153-159.  [22656]  6.  Bednarz, James C. 1988. Swainson's hawk. In: Glinski, Richard L.;        Pendleton, Beth Giron; Moss, Mary Beth; [and others], eds. Proceedings        of the southwest raptor management symposium and workshop; 1986 May        21-24; Tucson, AZ. NWF Scientific and Technical Series No. 11.        Washington, DC: National Wildlife Federation: 87-96.  [22650]  7.  Bednarz, James C.; Hoffman, Stephen W. 1988. The status of breeding        Swainson's hawks in southeastern New Mexico. In: Glinski, Richard L.;        Pendleton, Beth Giron; Moss, Mary Beth; [and others], eds. Proceedings        of the southwest raptor management symposium and workshop; 1986 May        21-24; Tucson, AZ. NWF Scientific and Technical Series No. 11.        Washington, DC: National Wildlife Federation: 253-259.  [22651]  8.  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]  9.  Burleigh, Thomas D. 1950. "Give Idaho hawks a break" biologist asks        nimrods; some species helpful to wildlife. Idaho Wildlife Review.        February: 6-7.  [21497] 10.  Call, Mayo. 1979. Habitat management guides for birds of prey. Techical        Note 338. Denver, CO: U.S. Department of the Interior, Bureau of Land        Management, Denver Service Center. 70 p.  [22451] 11.  Cowart, Linda. 1975. The desert hunters. Pacific Discovery. 28(1): 5-9.        [22655] 12.  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] 13.  Dodd, Norris L. 1988. Fire management and southwestern raptors. In:        Gliski, R. L.; Pendleton, Beth Giron; Moss, Mary Beth; [and others],        eds. Proceedings of the southwest raptor symposium and workshop; 1986        May 21-24; Tucson, AZ. NWF Scientific and Technology Series No. 11.        Washington, DC: National Wildlife Federation: 341-347.  [22648] 14.  DuBois, Kristi; Becker, Dale; Thornbrugh, Joe. 1987. Identification of        Montana's birds of prey. Montana Outdoors. 18(6): 11-31.  [3606] 15.  Dunkle, Sidney W. 1977. Swainson's hawks on the Laramie Plains, Wyoming.        Auk. 94: 65-71.  [22654] 16.  Emmerich, John M.; Vohs, Paul A. 1982. Comparative use of four woodland        habitats by birds. Journal of Wildlife Management. 46(1): 43-49.        [19283] 17.  Estep, J. A. 1989. Biology, movements, and habitat relationships of the        Swainson's hawk in the Central Valley of California. Sacramento, CA:        California Department of Fish and Game. 70 p.  [23124] 18.  Eyre, F. H., ed. 1980. Forest cover types of the United States and        Canada. Washington, DC: Society of American Foresters. 148 p.  [905] 19.  Garrison, George A.; Bjugstad, Ardell J.; Duncan, Don A.; [and others].        1977. Vegetation and environmental features of forest and range        ecosystems. Agric. Handb. 475. Washington, DC: U.S. Department of        Agriculture, Forest Service. 68 p.  [998] 20.  Gilmer, David S.; Stewart, Robert E. 1984. Swainson's hawk nesting        ecology in North Dakota. Condor. 86: 12-18.  [22653] 21.  Herron, Gary B.; Mortimore, Craig A.; Rawlings, Marcus S. 1985.        Red-tailed hawk. In: Nevada raptors: Their biology and management.        Biological Bulletin No. 8. Reno, NV: Nevada Department of Wildlife:        29-30.  [22694] 22.  Holland, Robert F.; Roye, Cynthia L. 1989. Great Valley riparian        habitats and the National Registry of Natural Landmarks. In: Abell, Dana        L., technical coordinator. Proceedings of the California riparian        systems conference: Protection, management, and restoration for the        1990's; 1988 September 22-24; Davis, CA. Gen. Tech. Rep. PSW-110.        Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific        Southwest Forest and Range Experiment Station: 69-73.  [13511] 23.  James, Paul C. 1992. Urban-nesting of Swainson's hawks in Saskatchewan.        Condor. 94: 773-774.  [23120] 24.  Kuchler, A. W. 1964. Manual to accompany the map of potential vegetation        of the conterminous United States. Special Publication No. 36. New York:        American Geographical Society. 77 p.  [1384] 25.  Landers, J. Larry. 1987. Prescribed burning for managing wildlife in        southeastern pine forests. In: Dickson, James G.; Maughan, O. Eugene,        eds. Managing southern forests for wildlife and fish: a proceedings;        [Date of conference unknown]; [Location of conference unknown]. Gen.        Tech. Rep. SO-65. New Orleans, LA: U.S. Department of Agriculture,        Forest Service, Southern Forest Experiment Station: 19-27.  [11562] 26.  Lehman, Robert N.; Allendorf, John W. 1989. The effects of fire, fire        exclusion and fire management on raptor habitats in the western United        States. In: Proceedings of the western raptor management symposium and        workshop; 1987 October 26-28; Boise, ID. Scientific and Technical Series        No. 12. Washington, DC: National Wildlife Federation: 236-244.  [22324] 27.  McGee, John Michael. 1976. Some effects of fire suppression and        prescribed burning on birds and small mammals in sagebrush. Laramie, WY:        University of Wyoming. 114 p. Dissertation.  [16998] 28.  Montana Natural Heritage Program. 1990. Animal species of special        concern. Helena, MT: Montana Natural Heritage Program. 5 p.  [13751] 29.  Moseley, Robert; Groves, Craig, compilers. 1990. Rare, threatened and        endangered plants and animals of Idaho. Boise, ID: Idaho Department of        Fish and Game, Nongame and Endangered Wildlife Program, Natural Heritage        Section. 33 p.  [19328] 30.  Olendorff, Richard R.; Kochert Michael N. 1977. Land management for the        conservation of birds of prey. In: Chancellor, R. D., ed. World        conference on birds of prey; Report of proceedings; [Date unknown];        [Location unknown]. [Place of publication unknown]: International        Council on Bird Preservation: 294-307. 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