CHAPTER 9 



HABITAT USE AND INTERSPECIFIC RELATIONS 



Food Habits 



Food habits of mule deer on and adjacent to the study 

 area were emphasized in earlier work by Mackie (1970), Knowles 

 (1975), and Komberec (1976). During 1976-1986, we obtained 

 additional information by collecting rumen samples from 

 hunter-killed deer during late October through November each 

 year, as well as from coyote-killed deer, trapping casualties, 

 road-killed deer, or deer deliberately collected for study. 

 The following discussion generally summarizes our knowledge of 

 food habits from both the earlier published reports and the 

 additional information. 



On an annual basis, shrubs comprised 62%, forbs 33%, and 

 grasses 5% of the mule deer diet during 1960-1964. Shrubs 

 comprised 50% or more of the diet during August through March, 

 and averaged 36% of the diet during May through July, their 

 period of lowest use (Figure 9.1). Peak use of shrubs 

 occurred during December and January (90%+). Forbs comprised 

 one-third or more of the diet during April through September. 

 Forb use was highest during May, June, and July, when it 

 comprised 60-70% of the diet of mule deer. Lowest use of 

 forbs occurred in December and January, coinciding with the 

 greatest use of shrubs. Use of grasses was relatively minor, 

 but peaks occurred during October and November of some years 

 and late March through April in all years. 



Seasonal Patterns 



Summer 



Forbs comprised 45-75% of the summer diet of mule deer, 

 averaging slightly over 50% (Mackie 1970, Knowles 1975). 

 Yellow sweetclover was the major forb species used, comprising 

 36-59% of the diet. A variety of other forbs were also eaten, 

 usually in minor amounts. The shrub, fragrant sumac, was the 

 second-most important forage species during summer, comprising 

 10-36% of the diet. Both Mackie (1970) and Knowles (1975) 

 noted that use of fragrant sumac increased as the abundance 

 and succulence of yellow sweetclover decreased. During 

 summer, use of fragrant sumac was primarily confined to leaves 

 and buds. Other shrubs, including snowberry, rose, and 

 chokecherry received increasing use as summer progressed. 

 Grasses received minor, incidental use during summer. When 

 sweetclover was scarce or absent, use of other forbs increased 

 to a small degree, but most of the lack of yellow sweetclover 

 was made up by increased use of fragrant sumac, snowberry, 

 rose, and chokecherry. 



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