Dissertation/Thesis Abstract

Evaluation of winter range habitat treatments on overwinter survival, density, and body condition of mule deer
by Bergman, Eric James, Ph.D., Colorado State University, 2013, 153; 3593359
Abstract (Summary)

The management and research of mule deer (Odocoileus hemionus ) in Colorado and throughout the Rocky Mountain West is an exciting arena for wildlife professionals as the prevailing view among biologists, managers, researchers, hunters, wildlife viewers and general wildlife enthusiasts is that they would like to see more deer on the landscape.

In Chapter 1, I used 4 years of data and 8 study units to evaluate the effect of habitat management on the overwinter survival of mule deer fawns. Habitat management consisted of different levels of habitat management efforts: reference study units received no habitat management, traditional habitat treatment units received mechanical disturbance and advanced habitat treatment units were comprised of both mechanical disturbances as well as follow-up chemical control of weeds and reseeding with desirable browse species. Mule deer fawns that overwintered on areas that received both a traditional treatment as well as follow-up treatments experienced an improvement in survival ( Ŝ = 0.768, SE = 0.085) over deer on winter range without habitat treatments (Ŝ = 0.675, SE = 0.112). When partitioned into different levels of treatment intensity, mule deer inhabiting winter range that advanced treatments (i.e., both traditional treatments and follow-up treatments) experienced higher survival (Ŝ = 0.768, SE = 0.0849) than deer on areas that experienced only traditional treatments (Ŝ = 0.687, SE = 0.108), which in turn experienced higher survival than in areas that had received no treatments (Ŝ = 0.669, SE = 0.113).

In my second chapter, I relied on recent advancements in abundance estimation methodologies to determine if habitat management strategies increased mule deer density. In order to estimate mule deer density, I conducted annual helicopter mark-resight surveys across the 8 study units that were utilized in chapter 1. Resighting probabilities (range 0.070–0.567) were best modeled as an interactive function of study unit and year, although sampling method was also important. A consistent pattern of higher deer density on advanced treatment study units was not observed despite its being the primary hypothesis of the study. Total deer densities did vary by latitude with 20–84 deer/km² in southern study units and 4–12 deer/km² in northern study units. I conclude that if population density is to be used as a population response variable, it only be used in tandem with other, possibly more sensitive parameters, such as overwinter survival of mule deer fawns.

In my third chapter, I investigate the relationships between habitat, body condition, and life history characteristics. With the increased availability of portable ultrasound machines and the refinement of hormonal assays, assessment of ungulate body condition has become a more accessible monitoring strategy. I employed body condition scoring, estimation of % ingesta-free body fat (%IFBF) and assessment of thyroid hormones (FT4 and FT3) as metrics to determine if landscape-level habitat manipulation affected body condition of adult (≥1.5 years old) female mule deer.

For my final chapter, I assimilate the knowledge and information gained from my first 3 chapters with the existing knowledge base surrounding mule deer population dynamics and population limitation within Colorado. Such reviews have been conducted periodically (e.g., 1960s and late 1990s) and have been precipitated by mule deer population declines. A dramatic decline in mule deer populations was detected during the final years of my field research but the underlying cause of this decline is yet to be determined. (Abstract shortened by UMI.)

Indexing (document details)
Advisor: Doherty, Paul F.
Commitee: Chong, Edwin C., Naug, Dhruba, White, Gary C.
School: Colorado State University
Department: Fish, Wildlife, and Conservation Biology
School Location: United States -- Colorado
Source: DAI-B 74/12(E), Dissertation Abstracts International
Subjects: Wildlife Management
Keywords: Colorado, Habitat, Management, Mule deer, Winter range
Publication Number: 3593359
ISBN: 978-1-303-36021-3
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