Prairie Falcon {Falco mexicanus) 



Distribution: Breeds in grasslands, breaks, and shrubsteppe from southeastern British Columbia 

 and southern Saskatchewan south to Baja California and west Texas, west of the 100th 

 meridian. Widespread during the breeding season in Montana (Bergeron et al. 1992), while 

 uncommon in western South Dakota (S.D. Omithol. Union 1991). Winters in grasslands and 

 open country within the breeding range east to eastern Kansas and Oklahoma, south to 

 southern Mexico. 



Habitat Use: Generally found in rather open grassland, sagebrush desert, and other arid habitats 

 with sparse tree cover and nearby cliffs and outcrops, including terrain above upper treeline 

 in high mountains. Habitat use varies with the availability of prey and cliff nest sites. Prey 

 items from nests in Carter County, Montana (Becker 1978, pers. comm.) included 76% birds 

 (Western Meadowlarks, bluebirds. Lark Buntings, Rock Doves, and American Kestrel) and 

 24% small mammals (Thirteen-lined Ground Squirrels and Least Chipmunks). In 

 northcentral Montana small mammals (at least 5 rodent species and cottontail rabbits) 

 comprised 57% of the prey items, while birds (at least 4 passerine species, American Kestrel, 

 Gray Partridge, and unidentified ducks) comprised the remaining 43% (Harmata 1991). 



Nest Sites: All Prairie Falcon nests (n = 26) reported by Becker (1978) from Carter County, 

 Montana were on cliffs ranging from 7-52 m high; mean nest height was 12.8 ± 10.8 m 

 above ground, with a range of 5-50 m. The 3 nest areas found in the Chalk Buttes and 

 Ekalaka Hills in 1994 were cliff faces, and the 4 nests from Harding County, South Dakota 

 with site descriptions (see Appendix 3) were also on cliffs. Harding County nests include 3 

 from South Cave Hills, 4 from North Cave Hills, and 6 from Slim Buttes between 

 1973-1989; at least 15% of these nest sites were used during multiple years. Cliffs are also . 

 the sites used in northeastern Wyoming (Phillips and Beske 1990, Phillips et al. 1990), 

 western North Dakota (Allen 1987), and other western states (Enderson 1964, Runde and 

 Anderson 1986). Nesting has occurred in old magpie nests (MacLaren et al. 1984) and on 

 transmission towers (Roppe et al. 1989). Nest exposures tend to be southerly (Runde and 

 Anderson 1986); 89% of the nests reported by Becker (1978) in Carter County, Montana 

 faced south to west. Most nests are scrapes (depressions) without twigs or sticks (Call 1978). 



Nest Success: Usually lays 3-6 eggs. Becker (1978) reported a mean clutch size of 4.8 in Carter 

 County, Montana in 1978; 65% of 20 active Prairie Falcon nests produced fledglings, with a 

 mean of 3.3 fledglings/nest. The mean brood size for 10 nests in Harding County, South 

 Dakota (Appendix 3) was 3.2; the mean number of fledglings/nest in northcentral Montana 

 was 2.8-4.3, depending on distance from oil and gas activity (Harmata 1991). 



Breeding Phenology: In Carter County, Montana, egg-laying was from mid-March to mid-April, 

 hatching from mid-May to mid-June, and fledging from late June to late July (Becker 1978). 

 In northcentral Montana, egg-laying took place in late April, with hatching in late May, and 

 fledging in early July (Harmata 1991). Nesting season lasts from mid- April through July in 

 South Dakota (S.D. Omithol. Union 1991). 



Status: Widespread and locally common in region; populations appear to be stable in Montana 

 and North Dakota (Dobkin 1994), and throughout westem North America (White 1994). 



Natural Heritage Program rank: G5; S4 in Montana; S3 S4B,S4N in South Dakota. 



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