Missouri Department of Conservation
Missouri Department of Conservation

Taxonomy

Common Name: HAWK, SWAINSON'S

Phylum: CHORDATA

Class: AVES

Order: ACCIPITRIFORMES

Family: ACCIPITRIDAE

Genus: BUTEO

Species: SWAINSONI

Taxonomic Authority: BONAPARTE

Taxonomy References: 002

Status

NONGAME
STATE RANK S2
GLOBAL RANK G5

Status References: 030 , 040 , 043 , 047 , 051

Habitat Summary

"Occur in prairies or grasslands with open groves and scattered trees."

Primary Habitat: "Grassland(matrix)"

References: 001 , 022 , 023

Distribution

General Occurrence in State:

"Uncommon transient in west, rare in east. Casual summer resident in southwest *49*. Has been identified as a \"species of management concern\" regarding viability of populations in the midwest *47*."

County Occurance

County Occurence
Known Likely Unknown Not Likely Historic Extirpated
ANDREW ADAIR
BARTON ATCHISON
BATES AUDRAIN
BOONE BARRY
BUCHANAN BENTON
CALLAWAY BOLLINGER
CAPE GIRARDEAU BUTLER
CHARITON CALDWELL
CLINTON CAMDEN
COLE CARROLL
FRANKLIN CARTER
GREENE CASS
HENRY CEDAR
HOLT CHRISTIAN
JACKSON CLARK
JASPER CLAY
LAWRENCE COOPER
MCDONALD CRAWFORD
NEWTON DADE
NODAWAY DALLAS
REYNOLDS DAVIESS
ST. CHARLES DEKALB
ST. CLAIR DENT
ST. LOUIS DOUGLAS
STODDARD DUNKLIN
VERNON GASCONADE
WRIGHT GENTRY
GRUNDY
HARRISON
HICKORY
HOWARD
HOWELL
IRON
JEFFERSON
JOHNSON
KNOX
LACLEDE
LAFAYETTE
LEWIS
LINCOLN
LINN
LIVINGSTON
MACON
MADISON
MARIES
MARION
MERCER
MILLER
MISSISSIPPI
MONITEAU
MONROE
MONTGOMERY
MORGAN
NEW MADRID
OREGON
OSAGE
OZARK
PEMISCOT
PERRY
PETTIS
PHELPS
PIKE
PLATTE
POLK
PULASKI
PUTNAM
RALLS
RANDOLPH
RAY
RIPLEY
SALINE
SCHUYLER
SCOTLAND
SCOTT
SHANNON
SHELBY
ST. FRANCOIS
STE. GENEVIEVE
STONE
SULLIVAN
TANEY
TEXAS
WARREN
WASHINGTON
WAYNE
WEBSTER
WORTH

References for distribution: 001 , 003 , 004 , 005 , 006 , 007 , 010 , 011 , 012 , 014 , 015 , 032 , 034 , 035 , 046 , 047 , 050 , 009 , 013 , 033 , 036 , 049

Distribution by Watersheds

Wyaconda R.
Miss. R. from Des Moines R. to MO. R.; and North R.
Cuivre R.
Dardenne Creek
Miss. R. from St. Louis to River Aux Vases
Meramec R.
Bourbeuse R.
Miss. R. from River Aux Vases to Ohio R.
Castor R. and Castor R. Diversion Channel
St. Francis R. from Wappapello Dam to Arkansas Border
Little R.
Mo. R. from Nishnabotna R. to Nodaway R.
Nodaway R.
Mo.R. from Nodaway to Kansas City
Platte R.
One Hundred and Two R.
Northwest Corner of Jackson County
Grand R. from Headwaters to Shoal Creek
Grand R. from Shoal Creek to MO. R.
Chariton R. from Shuteye Creek to Mo. R.
Little Chariton R.
Marais Des Cygnes from Headwaters to Little Osage R.
Little Osage R.
Marmaton R.
Osage R. from Headwaters to Warsaw, MO.
Sac R.
Pomme De Terre R.
South Grand R.
Osage R. from Bagnell Dam to Mo. R.
Gasconade R. from Headwaters to Big Piney R.
Mo. R. from Kansas City to Little Chariton R.
Mo. R. from Little Chariton R. to Gasconade R.
Mo. R. from Gasconade R. to Miss. R.
James R.
North Fork White R.
Black R.
Lost Creek
Spring R.
Indian Creek

Comments: "Likely to occur in units listed, based on county occurrence."

Distribution by Ecoregions

Mississippi River Alluvial Plains, Osage Plains, Ozark Highlands

Comments: ""

Distribution by Potential Natural Vegetation

Bluestem Prairie/Oak Hickory Forest
Oak-Hickory Forest
Oak-Hickory-Pine Forest
Southern Floodplain Forest

Distribution by Natural Divisions of Missouri

Glaciated Plains: Western
Glaciated Plains: Grand River
Glaciated Plains: Eastern
Glaciated Plains: Lincoln Hills
Big Rivers: Upper Missouri
Big Rivers: Lower Missouri
Big Rivers: Lower Mississippi
Ozark Border
Ozark Border: Missouri River
Ozark Border: Mississippi River
Ozark: Springfield Plateau
Ozark: Upper Ozark
Ozark: St. Francois Mountains
Ozark: Elk River
Ozark: White River
Ozark: Lower Ozark
Mississippi Lowlands: Crowley's Ridge
Osage Plains

Habitat Associations

Species is associated with "Terrestrial" habitats.

National Wetlands Inventory Association:

Aquatic Associations:

References for Aquatic Associations:

Habitat Types:

Perennial Grass (Warm season)
Perennial Grass (cool-season)
Savanna (Grass-Shrub)

References for Habitat Types: 037 , 048

Terrestrial Natural Communities:

Savanna
Dry Savanna
Dry-Mesic Savanna
Mesic Savanna
Wet-Mesic Savanna
Limestone/Dolomite Savanna
Chert Savanna
Sandstone Savanna
Sand Savanna
Igneous Savanna
Prairie
Dry Prairie
Dry-Mesic Prairie
Mesic Prairie
Wet-Mesic Prairie
Limestone/Dolomite Prairie
Dry Limestone/Dolomite Prairie
Dry-Mesic Limestone/Dolomite Prairie
Chert Prairie
Dry Chert Prairie
Dry-Mesic Chert Prairie
Sandstone/Shale Prairie
Dry Sandstone/Shale Prairie
Dry-Mesic Sandstone/Shale Prairie
Sand Prairie
Dry Sand Prairie
Dry-Mesic Sand Prairie
Hardpan Prairie
Primary
Cliff
Dry Limestone/Dolomite Cliff
Moist Limestone/Dolomite Cliff
Dry Sandstone Cliff
Moist Sandstone Cliff
Dry Chert Cliff
Moist Chert Cliff
Dry Igneous Cliff
Moist Igneous Cliff

References for Terrestrial Natural Communities: 019 , 021 , 022 , 023 , 037 , 048

Food Habits

Trophic Level:

"Carnivore"

Larval Food Habits

Comments for larval food habits:
""

References for larval food habits:

Juvenile Food Habits

Reptiles; Not Specified
Serpentes (snakes); Not Specified
Mammals; Not Specified
Leporidae (rabbits); Not Specified
Sciuridae (squirrels, chipmunks, prairie dogs); Not Specified
Geomyidae (pocket gophers); Not Specified
Icteridae (meadowlarks, blackbirds, orioles); Not Specified
Fringillidae (grosbeaks, sparrows, finches, and buntings); Not Specified
Insects Insects; Not Specified
Orthoptera (grasshoppers, crickets, mantids); Not Specified
Cricetidae (woodrats, mice, voles, lemmings); Not Specified
Mustelidae (weasel, skunk, otter, mink, badger); Not Specified
Birds; Not Specified
Phasianidae (quails and pheasant); Not Specified
Strigidae (typical owls); Not Specified
Alaudidae (larks); Not Specified

Comments for Juvenile Food Habits:
""

References Juvenile Food Habits 001 , 016 , 027 , 038

Adult Food Habits

Coleoptera (beetles); Not Specified
Amphibians; Not Specified
Salientia (frogs, toads, peepers, tree frogs); Not Specified
Reptiles; Not Specified
Sauria (lizards, skinks); Not Specified
Serpentes (snakes); Not Specified
Birds; Not Specified
Phasianidae (quails and pheasant); Not Specified
Ploceidae (weaver finches); Not Specified
Terrestrial Insects; Not Specified
Insects Insects; Not Specified
Orthoptera (grasshoppers, crickets, mantids); Not Specified
Mammals; Not Specified
Chiroptera (bats); Not Specified
Leporidae (rabbits); Not Specified
Sciuridae (squirrels, chipmunks, prairie dogs); Not Specified
Geomyidae (pocket gophers); Not Specified
Cricetidae (woodrats, mice, voles, lemmings); Not Specified

Comments for Adult Food Habits:
""

References Adult Food Habits 017 , 018 , 019 , 020 , 022 , 023 , 025 , 026 , 028 , 029 , 039 , 041 , 052

Niche Requirements

Egg Niche Requirements

References for egg niches requirements:

Feeding Larvae Niche Requirements

References for feeding larvae niche requirements:

Resting Larvae Niche Requirements

References for resting Larvae niche requirements:

Feeding Juvenile Niche Requirements

General habitat association specified in comments(00270)
Successional stage: stable prairie/grassland
Successional stage: climax grassland

References for feeding juvenile niche requirements: 019 , 021 , 022 , 023

Resting Juvenile Niche Requirements

Other niche requirements specified in comments(99999)
General habitat association specified in comments(00270)
Successional stage: stable prairie/grassland
Successional stage: climax grassland
Agricultural crops specified in comments(00670)

References for resting juvenile niche requirements: 016 , 019 , 021 , 022 , 023

Breeding Adult Niche Requirements

Other niche requirements specified in comments(99999)
Floodplain specified in comments(00220)
General habitat association specified in comments(00270)
Edge: woodland/water edge
Successional stage: stable prairie/grassland
Successional stage: climax grassland
Successional stage specified in comments(00370)
Leaf litter/ground debris specified in comments(00460)
Large lone trees specified in comments(00520)
Height of nest trees specified in comments(00580)
Shrubs specified in comments(00615)
Herbaceous cover (%) specified in comments(00620) Herbaceous cover (%) specified in comments
Windbreaks specified in comments(00673)
Conservation reserve program (CRP) fields
Human association: wooded farmsteads
Isolation from humans required; should be relatively inaccessible
Isolation from humans specified in comments(00700)
Bare ground (%) specified in comments(00710)

References for feeding Adult niche requirements: 016 , 017 , 018 , 019 , 020 , 021 , 022 , 023 , 024 , 038 , 039 , 041 , 042 , 045 , 048

Feeding Adult Niche Requirements

General habitat association specified in comments(00270)
Successional stage: stable prairie/grassland
Successional stage: climax grassland
Agricultural crops: crop stubble

References for feeding adult niche requirements: 019 , 021 , 022 , 023 , 052

Resting Adult Niche Requirements

General habitat association specified in comments(00270)
Successional stage: stable prairie/grassland
Successional stage: climax grassland
Agricultural crops: crop stubble

References for resting adult niche requirements: 016 , 019 , 021 , 022 , 023

Niche Requirement Summary

Agricultural crops specified in comments(00670)
Agricultural crops: crop stubble
Bare ground (%) specified in comments(00710)
Conservation reserve program (CRP) fields
Edge: woodland/water edge
Elevation specified in comments(00240)
Floodplain specified in comments(00220)
General habitat association specified in comments(00270)
Height of nest trees specified in comments(00580)
Herbaceous cover (%) specified in comments(00620) Herbaceous cover (%) specified in comments
Human association: wooded farmsteads
Isolation from humans required; should be relatively inaccessible
Isolation from humans specified in comments(00700)
Large lone trees specified in comments(00520)
Leaf litter/ground debris specified in comments(00460)
Other niche requirements specified in comments(99999)
Shrubs specified in comments(00615)
Successional stage specified in comments(00370)
Successional stage: climax grassland
Successional stage: stable prairie/grassland
Windbreaks specified in comments(00673)

Comments about Life History:

Code Comment
013 May reuse old nest year after year *17,19,20,22,23*
031 Fratricide is a cause of nestling mortality *38*
007 Laying season 2nd half of April in south to 1st half of June in north *22*. In canada most eggs laid 1st 2 weeks of June *23*. In WA nest building occurs in mid-April *19*. In CA nesting begins in April *20*. In KS breed 11 April - 10 June *21*
014 Nest height may range 10-35' above ground *23*. In WA nests rarely above 25' from ground *19*; another WA study found nest height 4.8-10.2 m *52*. In CA nest height may be 50' above ground *20*. In KS nests usually 35' above ground *21*
016 In OK nests may have 60 cm. Diameter *16*. Nest dimensions may be 3-4' outside diameter, 8-9" inside diameter, and 2-5" deep *22*. Nest dimensions according to bent 21-28" outside diameter, and 2-5" deep *23*
017 Incubation period 28 days *22,23*. In MT incubation may only take 25 days *18*
018 Clutch size 2-4, usually 2 *22,23*. In WA, MT, and CA clutches usually 2-3 eggs *18,19,20*. In OK clutch size 3 *16*. In KS clutch size 2 *21*. A WA study found average clutch size to be 2.5 eggs *25*. In WY average clutch size 2.55 eggs *17*. One study found average clutch 2.66 *38*. In NM study, average clutch 2.42 *41*
028 Average home range in WA study 886 ha *52*. In CO study, size of home range increased when pairs were exposed to periods of military training activity *42*
099 In OK juv. May exibit fratricide *16*. In WY 2.06 young per pair are fledged *17*. In WA fledging success average 1.3 young per nest *25*. In WA average brood size 1.5 young per nest *25*. In WY density of 1 pair per 6.7 sq. Km. Was found *17*. In WY may be on territory 16-51 days before laying eggs *17*. In WY adults may show preference for mate of same color phase *17*. Birds studied in WA were found to be relatively free from toxin contamination *25*. In NM study, average 1.94 young fledged per successful nest, 1.67 young fledged per nest *41*.
033 In WA arrive 1st week of April and leave by early fall *19*. In CA arrive by mid-March *20*.
035 In WY nests maybe preyed on by crows and owls *17*

Life History Information

Home range size specified in comments(028)
Periodicity: active in day
Mortality rate specified in comments(031)
Migration patterns specified in comments(033)
Regulatory factors specified in comments(035)
Other life history information specified in comments(099)
Origin in state: native
Seasonal distribution in state: spring/summer/fall
Seasonal distribution in state: neotropical migrants
Foraging strategy: hawking
Foraging sites: ground
Foraging sites: air
Breeding season specified in comments(007)
Mating system: monogamy
Duration of pair bond: pair for life
Nest/den site: shrubs
Nest/den site: trees
Nest/den site: dirt bank
Nest/den/spawning site tenacity specified in comments(013)
Nest height specified in comments(014)
Nest materials: grasses
Nest materials: twigs
Nest materials: sticks
Nest materials: bark
Nest materials: hair or feathers
Nest dimensions specified in comments(016)
Gestation/incubation period specified in comments(017)
Clutch/litter size specified in comments(018)
Number of broods/litter per year: one
Development of young at birth/hatching: altricial
Parental care of young: both parents

Comments about Life History:

Code Comment
013 May reuse old nest year after year *17,19,20,22,23*
031 Fratricide is a cause of nestling mortality *38*
007 Laying season 2nd half of April in south to 1st half of June in north *22*. In canada most eggs laid 1st 2 weeks of June *23*. In WA nest building occurs in mid-April *19*. In CA nesting begins in April *20*. In KS breed 11 April - 10 June *21*
014 Nest height may range 10-35' above ground *23*. In WA nests rarely above 25' from ground *19*; another WA study found nest height 4.8-10.2 m *52*. In CA nest height may be 50' above ground *20*. In KS nests usually 35' above ground *21*
016 In OK nests may have 60 cm. Diameter *16*. Nest dimensions may be 3-4' outside diameter, 8-9" inside diameter, and 2-5" deep *22*. Nest dimensions according to bent 21-28" outside diameter, and 2-5" deep *23*
017 Incubation period 28 days *22,23*. In MT incubation may only take 25 days *18*
018 Clutch size 2-4, usually 2 *22,23*. In WA, MT, and CA clutches usually 2-3 eggs *18,19,20*. In OK clutch size 3 *16*. In KS clutch size 2 *21*. A WA study found average clutch size to be 2.5 eggs *25*. In WY average clutch size 2.55 eggs *17*. One study found average clutch 2.66 *38*. In NM study, average clutch 2.42 *41*
028 Average home range in WA study 886 ha *52*. In CO study, size of home range increased when pairs were exposed to periods of military training activity *42*
099 In OK juv. May exibit fratricide *16*. In WY 2.06 young per pair are fledged *17*. In WA fledging success average 1.3 young per nest *25*. In WA average brood size 1.5 young per nest *25*. In WY density of 1 pair per 6.7 sq. Km. Was found *17*. In WY may be on territory 16-51 days before laying eggs *17*. In WY adults may show preference for mate of same color phase *17*. Birds studied in WA were found to be relatively free from toxin contamination *25*. In NM study, average 1.94 young fledged per successful nest, 1.67 young fledged per nest *41*.
033 In WA arrive 1st week of April and leave by early fall *19*. In CA arrive by mid-March *20*.
035 In WY nests maybe preyed on by crows and owls *17*

References for life history: 016 , 017 , 018 , 019 , 020 , 021 , 022 , 023 , 025 , 038 , 039 , 041 , 042 , 052

Management

Beneficial Management Practices:

Agricultural - develop/maintain hedgerows
Agricultural - develop/maintain windbreaks
Agricultural - establish crp (conservation reserve program) fields
Grassland - seasonal restriction of human use of habitats
Grassland - maintain natural vegetation (native)
Grassland - control grazing of domestic livestock
Grassland - prescribed/controlled burning
Grassland - maintain habitat diversity

Beneficial Management References: 001 , 044

Adverse Managment Practices:

Grassland - application of pesticides
Grassland - application of insecticides
Grassland - control of undesirable vertebrate species (coyotes, gophers)

Adverse Management References: 001

Comments on Management:
In IA study occurred in CRP (conserveration reserve program) fields *48*.

References for Management Comments: 048

References

Reference Code Citation
001 Unpb Wilson, Jim D. Mo Dept. Conserv. P.O. Box 180. Jefferson City, Mo 65102. (573)751-4115.
002 American Ornithologists Union. 1957. Checklist Of North American Birds, 5th Ed. Lord Baltimore Press. Baltimore, Md. 691 Pp.
003 Birds Of Squaw Creek National Wildife Refuge. 1975. U.S. Fish And Wildlife Service. Rf-663560-2.
004 Rising, J., T. Pucci, N. Johnson, and R. Dawson. 1978. Birds Of The Kansas City Area. Burroughs Audubon Soc. Of Kansas City And The Shawnee Mission Environ Sci. Laboratory, Shawnee Mission South High School, KS. 46 Pp.
005 Welcome To Swan Lake National Wildlife Refuge. U.S. Fish And Wildlife Service National Wildlife Refuge Pamphlet.
006 Anderson, D. 1973. Fall Survey. Bluebird 40(1):6-9
007 Comfort, J.R. 1975. Missouri Christmas Bird Count 1974. Bluebird 42(1):9-15.
008 Anderson, D. 1976. Spring Survey. Bluebird 43(1):17-22.
009 Goodge, W.R. 1977. Missouri Christmas Bird Count 1976-1977. Bluebird 44(1):7-16.
010 Robbins, M. 1977. Spring Survey. Bluebird 44(2):14-18.
011 Robbins, M. 1977. Spring Survey. Bluebird 44(4):24-28.
012 Robbins, M. 1978. Spring Survey. Bluebird 45(3):14-20.
013 Kleen, V.M. 1974. The Changing Seasons - Middlewestern Prairie Region. Amer. Birds 28(1):58-63.
014 Kleen, V.M. 1974. The Changing Seasons - Middlewestern Prairie Region, Amer. Birds 28(4):807-810.
015 Kleen, V.M. 1976. The Changing Seasons - Middlewestern Prairie Region. Amer. Birds 30(5):961-965.
016 Parker, J.W. 1979. Evidence For Fratricide In Swainson's Hawk (Accipitridae). Sw. Nat. 24(3):533-534.
017 Dunkle, S.W. 1977. Swainson's Hawks On The Laramie Plains, Wyoming. Auk 94:65-71.
018 Cameron, E.S. 1913. Notes On Swainson's Hawk (Buteo Swainsoni) In Montana. Auk 30(2):167-176, 381-394.
019 Bowles, J.H. and F.R. Decker. 1934. Swainson's Hawk In Washington State. Auk 51:446-450.
020 Sharp, C.S. 1902. Nesting Of Swainson's Hawk. Condor 4:116-118.
021 Johnston, R.F. 1964. The Breeding Birds Of Kansas. Univ. Ks Publs. Mus. Nat. Hist. 12(14):575-655.
022 Brown, L. and D. Amadon. 1968. Eagles, Hawks and Falcons Of The World. Vol. 1. Mcgraw-Hill Book Co. Ny, Ny. 414pp.
023 Bent, A.C. 1937. Life Histories Of North American Birds Of Prey. U.S. Nat. Mus. Bull. 167. 409 Pp.
024 Call, M.W. 1979. Habitat Management Guides For Birds Of Prey. U.S. Bur. Land Manage. Tech. Note 338. 70 Pp.
025 Bechard, M. 1981. Ddt And Hexachlorobenzene Residues In Southeastern Washington Swainson's Hawks (Buteo Swainsoni). Bull. Environm. Contam. Toxicol. 26(2):248-253.
026 Gloyd, H.K. 1925. Field Studies Of The Diurnal Raptors Of Eastern And Central Kansas. Wilson Bull. 37:133-149.
027 Pilz, W.R. 1976. Possible Cannibalism In Swainson's Hawk. Auk 93:838
028 Errington, P.L. and W.J. Breckenridge. 1938. Food Habits Of Buteo Hawks In North-Central United States. Wilson Bull. 50:113-121.
029 Platt, J.B. 1971. A Survey Of Nesting Hawks, Eagles, Falcons, And Owls In Curlew Valley Utah. Great Basin Nat. 31(2):51-65.
030 The Wildlife Code of Missouri. Missouri Department of Conservation, P.O. Box 180, Jefferson City, MO 65102. 573-751-4115.
031 Thom, R.H. and J.H. Wilson. 1980 The Natural Divisions Of Missouri. Trans. Mo Acad. Sci. 14:9-24.
032 Heilbrun, L.H. 1977. 1976-1977 Christmas Bird Count. Amer. Birds 31(4):428-909.
033 Anderson, D. 1976. Summer Survey. Bluebird 43(1):22-24
034 Robbins, M. 1977. Winter Survey. Bluebird 44(1):17-28.
035 Robbins, M. 1977. Summer Survey. Bluebird 44(2):19-22.
036 Wilson, J.D. 1983. Fall Survey. Bluebird 50(1): In Press.
037 Kelly, G. (Ed.) 1986. Animal Habitat Relations Handbook. Mo Dept. Of Conservation and U.S.D.A. Forest Service. Jefferson City, Mo. 293 Pp.
038 Bechard, M.J. 1983. Food Supply And The Occurrence Of Brood Reduction In Swainson's Hawk. Wilson Bull. 95(2):233-241.
039 Gilmer, D.S. and R.E. Stewart. 1984. Swainson's Hawk Nesting Ecology In North Dakota. Condor 86(1):12-18.
040 U.S. Fish and Wildlife Service. List Of Missouri Animal Notice Species, February 2, 1989. U.S. Fws, P.O. Box 1506, Columbia, Mo 65205.
041 Bednarz, J.C. 1988. A Comparative Study Of The Breeding Ecology Of Harris' And Swainson's Hawks In Southeastern New Mexico. Condor 90:311-323.
042 Anderson, D.E., O.J. Rongstad and W.R. Mytton. 1990. Home-Range Changes In Raptors Exposed To Increased Human Activity Levels In Southeastern Colorada. Wildl. Soc. Bull. 18(2):134-142.
043 The Checklist Of Rare And Endangered Species Of Missouri. 1991. Mo Dept. Of Conservation. Jefferson City, Mo. 44 Pp.
044 Shroeder, R.L., T.T. Cable and S.L. Haire. 1992. Wildlife Species Richness In Shelterbelts: Test Of A Habitat Model. Wildl. Soc. Bull. 20:264-273.
045 Cable, T.T., R.L. Schroeder, V. Brack, Jr., and P.S. Cook. 1992. Summer Bird Use Of Kansas Windbreaks. Prairie Nat. 24:175-184.
046 Unpb Missouri Department of Conservation Heritage Database. P.O. Box 180, Jefferson City, Mo 65102.
047 Thompson, F.R., S.J. Lewis, J. Green and D. Ewert. 1993. Status Of Neotropical Migrant Landbirds In The Midwest: Identifying Species Of Management Concern. Pp. 145-158 In Finch, D.M. and P.W. Stangel, Eds. Status And Management Of Neotropical Migratory Birds. Sept. 21-25, Estes Park, Co. Gen. Tech. Rep. Rm-229. Fort Collins, Co: Usda, Forest Service, Rocky Mountain Forest and Range Exp. Sta. 422 Pp.
048 Best, L.B., K.E. Freemark, J.J. Dinsmore and M. Camp. 1995. A Review And Synthesis Of Habitat Use By Breeding Birds In Agricultural Landscapes In Iowa. Am. Midl. Nat. 134:1-29.
049 Easterla, D.A., M.B. Robbins and R.A. Anderson. 1992. Annotated Check-List Of Missouri Birds. The Audubon Society Of Missouri.
050 Jacobs, B. and J.D. Wilson. 1997. Missouri Breeding Bird Atlas 1986-1992. Mo Dept. Of Conservation. Natural History Series No. 6. Jefferson City, Mo. 430 Pp.
051 Missouri Natural Heritage Program. 2004. Missouri Species and Communities of Conservation Concern Checklist. Missouri Department Of Conservation. Jefferson City, Missouri. 47 Pp.
052 Bechard, M.J. 1982. Effect Of Vegetative Cover On Foraging Site Selection By Swainson's Hawk. Condor 84:153-159.