TABLE 3. Individual skulls recovered from raptor pellets collected 

 throughout the Centennial Sandhills, Beaverhead County, in 1999. 



Montana in valley bottom and foothill sage plains 

 and grasslands only in the southwestern part of the 

 state (Hoflfinanetal. 1969b, Zegers 1984). 



Raptor pellets contained remains of 1 1 9 individu- 

 als (Table 3) of which 112 represented 6 mammal 

 "species". Birds and "other mammal" made up 

 the remaining 7 individuals. Proportions of Micro- 

 tus, Peromyscus, and Tiiomomys in pellet 

 samples differed significantly from our trapping 

 results (G = 77.6 l,df= 2, P<0.001). Almost 

 half of the trap captures were Peromyscus, while 

 this species represented only 3% of the pellet 

 sample. Also striking was the ratio of Microtus 

 montanus to M. pennsylvanicus in the two 

 samples (G = 50.362, df= !,/'< 0.001). Nearly 

 all of the 40 identified voles in our traps were M. 

 montanus, but this species made up less than 

 40% of the pellet sample. 



Where the 2 microtine species co-occur, M 

 pennsylvanicus prefers moist areas while M. 

 montanus is found more often in drier sites 

 (Hodgson 1 972); our trap results identify this as 

 the pattern for the Centennial Sandhills, with M. 

 pennsylvanicus present only infrequently near the 

 perimeter of the sandhills proper Raptors (owls, 

 harriers, buteos: Appendix 8) probably hunted 

 most frequently over the extensive wetlands to the 

 south of the sandhills, capturing M 

 pennsylvanicus where it is likely more abundant. 



and returned to perches in the sandhills to digest 

 their meals and cast pellets. This hypothesis is 

 supported by the presence of three Muskrat 

 (Ondatra zibethicus) skulls in the pellet sample. 

 Peromyscus tends to avoid wet habitats (Clark 

 and Stomberg 1985), explaining its low represen- 

 tation in raptor pellet samples and providing 

 additional support for the above hypothesis. 



Carnivores : We detected 3 carnivore species 

 during our survey. Coyotes (Canis latrans) were 

 often heard in both portions of the sandhills, and 2 

 dens were found (one each in the East and West 

 hills). We noted little sign of Badger {Taxidea 

 taxus), but found a skull in the West Hills. Red 

 Fox (Vulpes vulpes) was seen once, on 2 July in 

 the East Hills. Coyote and/or Red Fox probably 

 raided some of our frap lines, as there was evi- 

 dence that a carnivore had disturbed fraps on a 

 few occasions. We failed to find any sign of 

 Striped Skunk {Mephitis mephitis) in the 

 sandhills, but anticipate that this species is some- 

 times present, especially along the southern 

 margins adjacent to wetlands. 



Ungulates : Our survey documented 3 ungulate 

 species in the Sandhills. A small band of Prong- 

 hom (Antilocapra americana) was observed 

 daily in the West Hills (2 fawns on 28 July) and 

 another small band was seen less frequently in the 

 East Hills. We observed a single cow Elk 



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