. Ecology of sympatric populations of mule deer and white-tailed deer in a prairie environment . Fig. 6. Estimated white-tailed deer population trends on the Cherry Creek study area for autumn, early winter and early spring, 1975-1987. Declining whitetail numbers were first evident in estimates for autumn, winter, and spring 1983-1984. Sharp declines occurred during 1984-1986 (Fig. 6, Table 6). Only 16 whitetails were counted on the area during the aerial surveys in early winter 1986 and 9 in spring 1987, when a maximum residual population of 30 was estimated. Overall, during 1975-1986, estima
. Ecology of sympatric populations of mule deer and white-tailed deer in a prairie environment . Fig. 6. Estimated white-tailed deer population trends on the Cherry Creek study area for autumn, early winter and early spring, 1975-1987. Declining whitetail numbers were first evident in estimates for autumn, winter, and spring 1983-1984. Sharp declines occurred during 1984-1986 (Fig. 6, Table 6). Only 16 whitetails were counted on the area during the aerial surveys in early winter 1986 and 9 in spring 1987, when a maximum residual population of 30 was estimated. Overall, during 1975-1986, estimates indicated seasonal populations approximately doubled from 1978 through 1982, then decreased by 70-80% by 1985- 1986. The difference between the estimated high summer population of 585 in summer 1983 and the low of 30 in spring 1987 represented a nearly 20-fold fluctuation in total numbers during this study. Whitetail population trends on the Cherry Creek area during 1975-1986 generally followed those indicated for white-tailed deer by other research and management studies in eastern Montana. Populations were relatively low or varied among habitats during the mid 1970s, increased to peaks and perhaps all time highs during 1982-1983, and stabilized or declined during 1983-1985 (Mackie et al. 1985). Data for white- tailed deer populations along the lower Yellowstone River (Dusek et al. 1989) indicated trends very similar to those observed on our study area, though the magnitude of decline from 1983 through 1986 was much less on that area. Productivity and Herd Composition Data on initial productivity of whitetails were limited to a small sample tested for pregnancy during 1983-1985, fawn:doe ratios derived from observations of marked females during summer 1983 and 1984, and classifications during all aerial surveys in autumn and winter. Pregnancy tests showed all but one (a 2-year-old) of 12 females examined were pregnant (Wood 1987). Although fawmfemale ratios derived from se
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