Date of Award:

1-1-1979

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Ecology

Advisor/Chair:

Philip J. Urness

Abstract

This s tudy examined feeding behaviors and habitat preferences of mule deer (Odocoileus hemionus hemionus) and elk (Cervus canadensis nelsoni) in aspen (Populus tremuloides) and lodgepole pine (Pinus contorta) types. Specific purposes were 1) to determine where deer and elk, undisturbed by humans, prefer to graze and rest within these two types and 2) to consider what species- specific characteristics contribute to their differing forage and habitat preferences.

Tame free-ranging mule deer and elk were observed for 24-hour periods biweekly through summer to determine their grazing and resting preferences for various habitat subunits. Relative distributions of deer and elk fecal groups were also recorded and compared with actual distribution of the animals . Species dry-weight compositions of monthly diets in the aspen type and lodgepole pine type were quantified by the bite count technique and used as basis for assessing consumption rates , intake and certain aspects of diet quality. In particular, relative digestive capacities of deer versus elk were investigated by using rumen inocula from each species in the fermentation of that animal' s diet, as well as in fermentation of the other species' diet . Crude protein values of diets in the aspen type were also determined monthly and compared with values reported for deer and elk in the lodgepole pine type.

In either type , both deer and elk exhibited strong grazing preference for open habitat subunits. However, elk most preferred highly productive meadow bottoms, whereas deer most preferred less productive clearcut lodgepole pine. Aspen forest subunits were also preferred by deer. Clearcutting greatly increased deer and elk grazing use of these areas in the lodgepole pine type, but aspen clearcuts were used about equally to uncut aspen, even though forage production doubled. The reason deer used meadow bottoms less than elk is attributed to the deer's preference for a more digestible diet; deer were generally more selective than elk, especially in meadow subunits where density of vegetation and abundance of nonpreferred grasses and sedges apparently interferred with forage selection and prevented maximum forage consumption rates. Elk had significantly greater digestive capacity than deer and were apparently better adapted to using a more diverse array of plant species as food. In any case, consumption rates were highest on subunits the animals most preferred to graze. The fact that both species made considerable use of less preferred habitat, where consumption rates were "suboptimal", suggests that deer and elk are innately motivated to explore their environments for alternate food resources.

Elk generally preferred to bed near where they finished feeding, although always in close proximity to cover. In contrast, deer generally retreated to specific beds which they used repeatedly t hroughout the summer . Deer resting behavior made them better adapted than elk to cope with biting insects.

Relative distributions of deer and elk pellet groups differed significantly from actual habitat use by either animal. Importance of the most valuable habitat was underestimated by pellet group distributions, and value of less important habitat was overestimated.

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