Seasonal sex and age ratios calculated from classified observations of 

 white-tailed deer are shown in table 23. Classified observations of 82 deer 

 during the fall of 1977 gave production ratios of 74 fawns: 100 females, 64 fawns :i 

 100 adults, and 20 bucks: 100 females. Ratios of 117 fawns:100 females, 109 

 fawns:100 adults, and 10 bucks:100 females were calculated from 78 observations 

 during the winter of 1977-1978. Comparable production data from studies of white- 

 tailed deer in eastern Montana are shown in table 23. Recent white-tailed deer 

 harvest estimates are summarized in Appendix L. 



Sample abundances of white-tailed deer for the roadside wildlife survey 

 routes are shown in figure 32. Note that the largest number of white-tailed 

 deer were seen along the Circle route, especially in fall and early winter. 

 These represented several resident herds frequenting an area of cropland, snow- 

 berry-rose drainages, and nearby cottonwood groves near the beginning of the 

 route. Fair numbers were seen in the river-bottom cottonwood forest and ri- 

 parian shrubbery of the Missouri River route, but the number of observations 

 here was likely biased downward due to dense cover. Few white-tailed deer were 

 seen on the other routes; none were seen on the Dreyer Ranch route. 



Pronghorn Antelope . Data were recorded for 9296 observations of pronghorn 

 antelope in 1167 groups during the study period (table 24). Seasonal changes in 

 pronghorn group size are shown in figure 26. Groups were largest in winter, 

 when the animals gathered in large herds on winter ranges, and smallest in 

 late spring and early summer, when herds are small and widely dispersed. This 

 seasonal change in group size is consistent with the findings of other studies 

 (Bayless 1969, Kitchen 1974, Martin 1977). The average yearlong group size was 

 8, and the largest group encountered numbered 130 during the severe winter of 

 1977-1978. I 



The distribution of pronghorn observations by season is shown in maps 14- 

 20. During the winter of 1977-1978, aerial surveys were confined to the vicinity 

 of the proposed mining area; therefore, distribution throughout the reconnais- 

 sance area were not obtained. Winter concentrations of pronghorn antelope were 

 indicated along Highway 24 and in the southwest corner of the reconnaissance 

 area (map 14). Pronghorn antelope did not appear to winter on the proposed 

 mining area; only one winter sighting of a group of 30 pronghorn antelope was 

 recorded there (near the southern boundary). The spring 1977 aerial survey 

 revealed that pronghorn antelope were dispersed over the entire reconnaissance 

 area, with relatively larger numbers in the southern half (map 15 and 16). 

 Pronghorn antelope occurred regularly on the proposed mining area during spring, 

 concentrating on the southern sections and in the vicinity of the Waller Ranch. 

 The distribution of antelope on the reconnaissance area and proposed mining area 

 remained similar to the spring distribution during the summer and fall of 1977 

 (maps 17-19). The 1977-1978 winter aerial survey in late January revealed that 

 pronghorn antelope were located mainly in the southwest quarter of the reconnais- 

 sance area (map 20). No pronghorn antelope were sighted on the proposed mining 

 area during the winter. General observations indicated that some pronghorn 

 antelope on the reconnaissance area prof^ably moved southward out of this area 

 during the severe winter of 1977-1978, leaving reduced density in comparison 

 to the moderate wintere of 1976-1977. 



Minimum antelope density estimates obtained for each season (based on 

 aerial surveys of the reconnanssance study area) are as follows: spring, 0.2/ 

 km2 (0.4/mi2), summer, 0.2/km2 (o.5/mi2); fall, 0.3/km^ (0.7/mi^); winter I 



120 



