Evaluation of Winter Food Choices by Tame Mule Deer

Abstract

Use of tame animals, particularly mule deer (Odocoileus hemionus), in food habits studies has become a widely used technique. Major advantages include the opportunity to identify forage species and plant parts eaten and better control of experimental design (Wallmo and Neff 1970). The main disadvantage is the unquantified relationship between tame and wild ungulate forage choices. Evidence supporting correlation between them is mostly empirical, based on observations of the 2 feeding together or separately on the same or similar areas (Buechner 1950, McMahan 1964, Healy 1967, Neff 1967, Arthur 1977). However, Markgren (1966) reported tame moose (Alces alces) calves ate little juniper (Juniperus sp.), an important winter food for wild moose, and Neff (1974) conceded that winter stress conditions could force wild deer to eat some forages not readily acceptable to tame deer. From a quantitative assessment of tame deer performance, Regelin et al. (1976) concluded artificial feed had little effect on selection of major forage species by tame mule deer fawns on a pinyon-juniper (Pinus edulis-Juniperus osteosperma) range during fall. Since forage availability is much greater during fall than winter, it was desirable to expand evaluations to include critical midand latewinter periods. The study objective was to determine if forage selections by tame deer maintained on artificial feed in a pen environment are similar to those of tame deer subsisting on native forage on pinyon-juniper range during winter. STUDY AREA AND METHODS