Year of Award

2020

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Wildlife Biology

Department or School/College

Wildlife Biology Program

Committee Chair

Chad J. Bishop

Commitee Members

Joshua J. Millspaugh, Eric J. Bergman, Ragan M. Callaway

Keywords

Alces alces, Colorado, moose, nutrition, occupancy, resource selection

Publisher

University of Montana

Subject Categories

Behavior and Ethology | Other Forestry and Forest Sciences | Other Nutrition | Population Biology

Abstract

Across much of North America, moose populations (Alces alces) are declining due to disease, predation, climate, and anthropogenic pressures. Despite this, populations of moose in Colorado have continued to grow. Studying successful (i.e., persistent or growing) populations of moose can facilitate the continued conservation of the species by identifying habitat features critical for moose persistence.

First, I evaluated calving success of moose in Colorado and the impact of willow habitat quality and nutrition. I then estimated the probability of female moose having a calf using repeated observations in a Bayesian occupancy model. I assigned values for dry matter digestibility, browse intensity, willow height, willow cover, and leaf length based on overlapping sample locations with estimated individual moose homeranges and tested the effect on calf presence. Willow height had the strongest predictive effect on calf presence and was the only covariate with credible intervals not overlapping zero. Dry matter digestibility had no effect, while browse intensity and leaf length were uninformative. Results presented here suggest that the quality (i.e., age and structure) of willow habitat are important for female moose with calves. This work sets the stage for future research on the structure of willow habitat and the incorporation of additional remotely sensed data.

Second, I used a resource selection function to evaluate resource selection by moose in Colorado and the effect of large-scale bark beetle disturbance. Bark beetles have impacted forests across North America, decreasing canopy cover and increasing solar radiation reaching the forest floor. These disturbances lead to an increase in ground forage but have been hypothesized to have a negative impact on thermally sensitive species such as moose. I evaluated resource selection at two scales: a large population scale and finer movement-based scale. The strongest selection by moose was for distance to willow, followed by elevation. Selection for beetle-disturbed habitat was mixed across populations and scales showing little overall effect. The lack of selection for beetle disturbed habitat suggests mixed influences on resource selection by moose. Undisturbed forest had moderately strong positive selection at both scales, illustrating the importance of maintaining undisturbed forest habitat for moose.

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