9 

 average distance which separated active nests was 1911 m (SD 

 = 659.15, n = 8) and I found that each active territory 

 contained an average of 2.31 nests (including the active 

 nest and any alternate nests) (SD = 1.92, n = 16). Eight 

 territories contained the active nest only, whereas one 

 territory contained seven alternate nests. 



The single aerial survey proved to be quite efficient. 

 During a period of two hours I located two Ferruginous Hawk 

 nests in the approximately 7800 ha (19200 acres) surveyed. 

 However, both nests were inactive. I subsequently surveyed 

 the area on foot and by vehicle, discovering one additional 

 inactive Ferruginous Hawk nest and an active Red-tailed Hawk 

 nest from which young had recently fledged. 



Ferruginous Hawks chose a variety of substrates for 

 nesting, most commonly upon rocky outcrops (Figure 3). 

 Other than those nests on cliffs or in trees, most were 

 quite accessible from the ground, potentially accessible to 

 ground predators. Nests were oriented nonrandomly with 

 hawks preferring to orient their nests with a southern 

 exposure [x = 190.84° , circular standard deviation = 

 76.94", n = 48; Rayleigh's test, z = 7.91, p < 0,0001 (Zar 

 1974) ] (Figure 4) . 



The slope upon which Ferruginous Hawks placed their 

 nests was quite variable and the mean slope was quite high 

 (X = 62.8%, SD = 40.2%, n = 50) (Figure 5). Most nests were 



