with saltgrass, silver sagebrush (p<.001), and water (p<.01), and were signif- 

 icantly and negatively correlated with time (p<.OOT). | 



Mourning Dove . Sample abundances of mourning doves for the five roadside 

 routes are plotted in figure 10. Spring arrival occurs in early April, and the 

 peak of breeding activity occurred in late June and July, as confirmed by nesting 

 data (table 10), and extended from mid May through early August. Scattered 

 clumps of silver buffaloberry in open coulee bottoms wer? the preferred nesting 

 habitat in the proposed mining area, although a variety of other trees and shrub 

 were also using for nesting. Highest numbers per route were seen along the 

 Prairie Elk route in April and May and along the Missouri River in July and 

 August. Sample abundances were similar for the Circle and Flowing Well routes, 

 and were lowest for the Dreyer Ranch route, although high densities were recor- 

 ded on tne silver buffaloberry-silver sagebrush breeding bird census grid loca- 

 ted adjacient to this latter route. Sample abundances were found to be signif- 

 icantly and positively correlated with trees and tall shrubs (p<.001), culti- 

 vated land, silver sagebrush, and horizontal juniper (p<.01), and were signif- 

 icantly and negatively correlated with time and grassland (p<.01). Most mourn- 

 ing doves had left the area by mid-September, 1977, although a few individuals 

 were seen in October of 1975 and November of 1977. Baskett et al . (1978) noted 

 that call frequencies for unmated males are 6-13 times greater than those of 

 mated males; this may partly explain the July peak in sample abundances, al- 

 though the present study included both calling and silent individuals in counts. 

 Data^gathered during the nationwide mourning dove call-count survey revealed a 

 significant decline in breeding population (p<.10) within the Missouri Plateau 

 unglaciated stratum (in which the proposed mining area is located) over the per- 

 iod 1965-1976 (Ruos 1974; Dolton 1976). ^ 



Great Horned Owl . Great horned owls occurred yearlong in relatively low 

 densities throughout the study area, and were most frequently encountered in 

 the vicinity of farm groves and cottonwood groves. Individuals were observed 

 on the proposed mining area, but no active nests were found. Preliminary analy- 

 sis of pellets collected during this study indicate a reliance on desert cotton- 

 tails, deer mice, and voles as prey items; the pellets have been stored by DNRC 

 awaiting more complete analysis. 



Burrowing Owl . Burrowing owls were rare and local in rolling grassland 

 habitats. Two active nests were located during this study (table 10), one near 

 the edge of a prairie dog town along the Missouri River roadside survey route, 

 and one near the start of the Circle roadside route. A group of fledged young 

 were seen several miles northwest of Circle, in a prairie dog town near the 

 head of Hungry Creek, but the nest site could not be found. A single breeding- 

 season observation was made within the proposed mining area. Another owl was 

 seen at the entrance to a burrow about 300 m (1000 feet) southeast of the pro- 

 posed mining area, but was not seen on subsequent visits to the site. 



Eastern Kingbird . Spring arrival of the eastern kingbird on the study 

 occurred in early May, with the peak of breeding in late June and early July 

 (figure 11). The July peak in sample abundances probably represents the in- 

 fluence of newly fledged young. The Dreyer Ranch and Missouri River routes 

 apparently traversed the most suitable breeding habitat of this species, as 

 sample abundances were highest for these two routes. Sample abundances (May- 



78 



