13 



placed on the upper 3 5% of these relatively steep slopes 

 (Figure 6) . 



Habitat surrounding 4 3 Ferruginous Hawk nests was 

 largely composed of a mixture of grassland and shrubland. 

 Within 100 m (300 ft) of the nest, the quantity of grassland 

 and shrubland was approximately equivalent, whereas the 

 majority of the area within 1.6 km (1 mile) was composed of 

 grassland (Figure 7) . However, most of the nests were found 

 within the Sagebrush ( Artemisia tridentata ) Steppe 

 Association (Kuchler 1964) (Figure 8) . 



Productivity of Ferruginous Hawks throughout the study 

 area and the Centennial Valley was variable with 81.5% of 

 nests fledging at least one young [x = 1.93 fledglings, SD = 

 1.38 fledglings, n = 27 (all active nests); x = 2.36 

 fledglings, SD = 1.14 fledglings, n = 22 (successful nests)] 

 (Figure 9) . The most common number of young fledged per 

 nest was two. Five nests failed to fledge young, apparently 

 due to a number of factors including removal of the nest 

 from a power pole by utility workers (Scott Jackson, U.S. 

 Fish and Wildlife Service, pers. comm. ) , predation by a 

 corvid, possible shooting of a nestling, chilling of eggs in 

 a nest near a salt lick, and failure to lay eggs by one 

 pair. 



Through identification of 87 prey items I determined 

 that Ferruginous Hawks in the southwest Montana study area 

 preyed primarily upon small rodents, especially ground 



