Range relationships of mule deer in the prairie habitat, northcentral Montana

A study was conducted in the Cottonwood Creek area in the prairie habitat of northcentral Montana during summer and winter to obtain quantitative data on seasonal distribution, range use, food habits and interspecific relationships of mule deer and cattle.Vegetation of the area included three major types: Silver Sage, Big Sage, and Grassland.Canopy coverages and frequencies of occurrence were determined for low-growing taxa on representative sites in each of the types.Use of vegetation types by mule deer during both summer and winter was determined by recording the location of 1,812 and 1,086 observations of mule deer from the ground and air, respectively.The Big Sage and Grassland Types combined received 81 and 99 percent of the use for summer and winter, respectively.Sixty-four percent of the 2,332 observations of cattle for the period May 1 to November 1 occurred in the Silver Sage Type compared to 31 percent in the Grassland Type.Both mule deer and cattle used the Silver Sage Type during late summer.Food habits of mule deer were determined from the examination of 29 rumens and 79 feeding sites.Volume of browse averaged 43, 81, 60 and 59 percent of the rumen contents for summer, fall, winter and spring, respectively.Forbs constituted 54 percent of the rumen contents for samples taken in summer.Yellow sweetclover, snowberry, rubber rabbitbrush and creeping juniper were the most important items in the diet during summer, fall, winter and spring, respectively.Grass constituted 17 percent of the diet during spring but was insignificant during other seasons.Grass accounted for 67 and 85 percent respectively, of the summer and early fall diets of cattle as determined from the examination of 52 feeding sites.Forbs, including yellow sweetclover, were important in early summer.Greasewood, snowberry, and chokecherry were shrubs used by cattle.Hog-dressed weights averaged 70 percent of whole weights of 18 mule deer.Kidney fat indices for mule deer collected between January and June averaged 108, 36, 20 and 11 percent, respectively, for yearling females, older females, male fawns and yearling males.An average ovulation incidence of 2.0 and a conception rate of 90 percent were determined for females collected from January to April.Fawn:female ratios for winter were 106:100 and 104:100 as determined by ground and aerial observations, respectively.There appeared to be some land use but no significant forage competition between mule deer and cattle.