This study of the ecology and condition of white-tailed deer (Odocoileus virginianus) was conducted on Missouri River bottomlands in northcentral Montana from June, 1964, to June, 1965. Range use was evaluated from 4,647 field observations of whitetails. Forty and 33 percent of summer observations, and 22 and 35 percent of fall observations, were made in the meadow vegetation type and alfalfa fields, respectively. Fifty percent of winter and 19 percent of spring observations were in the cottonwood type. The weed type accounted for 26 and 53 percent of winter and spring observations, respectively. Food habits were evaluated from analyses of 48 rumen samples and examination of 57 feeding sites. Browse averaged 45, 81, 65, and 43 percent of the contents of rumen samples for summer, fall, winter, and spring, respectively. Forbs averaged 54, 17, 29, and 18 percent for the same seasons. Grass was present in rumen samples during all seasons but was a minor item except in spring when its volume averaged 38 percent. Western snowberry (Symphoricarpos occidentalis), with values of 95 and 27 percent, respectively, for frequency and average volume of all rumen samples, was the most important food plant. Volume of snowberry decreased from 60 to 1 percent and volume of kochia (Kochia scoparia), increased from 6 to 41 percent from early to late winter. Poor physical condition of the deer suggested this change was due to range depletion. Classification of 188 whitetails in December showed a low fawn/doe ratio of 16 to 100, but 12 pregnant females examined December to June averaged two fetuses each. Minor use of bottomlands by mule deer (Odocoileus hemionus) and elk (Cervus canadensis), especially during winter and spring, precluded significant competition with whitetails. There was severe overlapping use of browse by cattle and whitetails during winter, as indicated by utilization of plants along transects.
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