6 

 situated directly (not elevated) upon the ground; outcrop = 

 nest situated on a rocky outcrop, the size of which ranged 

 from < Im to several meters in height; rimrock or bluff = a 

 linear escarpment or fault-line, smaller than a cliff and up 

 to approximately 12m in height; cliff = less linear than 

 rimrock and usually > 12m in height; tree = conifer or 

 deciduous tree, or shrub; and power pole. The activity 

 status of each nest was determined, number and approximate 

 age of young were recorded, slope and aspect were measured, 

 prey items were enumerated, and pellets were collected at 

 each nest. Additionally, I visually estimated the percent 

 cover and percent quantity of major vegetative cover types 

 primarily including grassland, shrubland, and shrub/grass 

 mosaic areas within a 100 m radius of the nest and within a 

 1.6 km (1 mile) radius of the nest. I determined the 

 habitat association within which each nest occurred from 

 maps located at the Dillon Resource Area office (Kuchler 

 1964) . 



Ferruginous Hawk pellets were dissected with a 10-30X 

 dissection scope, prey items were identified, and prey were 

 enumerated, corrected to the minimum number of individuals 

 represented for each nest or collection date. Beetles 

 (Carabidae and Scarabaidae) were treated as though they were 

 incidentally ingested, hence, were not included in the 

 analysis. Diet diversity was calculated for the complete 

 study area (Ludwig and Reynolds 1988) . 



