Year of Award

2020

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Wildlife Biology

Department or School/College

W.A. Franke College of Forestry and Conservation

Committee Chair

Dr. Victoria J. Dreitz

Commitee Members

Dr. Douglas W. Smith, Dr. Todd E. Katzner, Dr. Jedediah Brodie

Keywords

Golden Eagle, Habitat, Reproduction

Publisher

University of Montana

Subject Categories

Ornithology | Population Biology

Abstract

In the United States (US), National Parks are considered the “crown jewels” of protected lands. However, the importance of National Parks to wildlife populations and the species that inhabit them is not often quantified, thus, requiring a better understanding of National Parks as a conservation tool. Golden eagles (Aquila chrysaetos) are a North American species of conservation concern and territories in the northern range of Yellowstone National Park (YNP) are relatively dense. However, average reproductive rates over the past ten years (2011-2020) have been low (productivity = 0.34, nest success = 28%). The contrast of high density and low reproduction has stimulated questions regarding what environmental factors limit reproductive success. The overall objective of this study is to identify spatial and temporal components of golden eagle habitat that explain reproductive demographics in YNP’s northern range. To accomplish, I first examined resource selection at multiple spatial scales during two seasonal periods influential to reproduction. I found that golden eagles select home ranges in areas with low forest cover and in close proximity to open water. Within the home range I found that golden eagles select for increasingly rugged topography and upper slopes increasing to ridgelines. Additionally, I found weak evidence that eagles are selecting prey habitat based on season. I then used the resource selection analysis findings coupled with yearly weather variation to examine their effects on nest initiation/egg-laying and successfully fledging nestlings. Results indicate that increasing occasions of prolonged precipitation and severe weather negatively influence both nest initiation and success. I found weak evidence that home ranges with more rugged terrain and territories in closer proximity to neighboring territories positively influence nest success. The resource selection analysis reaffirms the importance of increased openness and topography near prey habitat on eagle presence and daily needs. Overall, my study advances our understanding of the drivers of low reproductive rates of golden eagles in the northern range of YNP. Harsh weather negatively influences nest initiation and success with weak evidence of a positive effect for spatially distributed resources. Given the potential consequences of low reproductive success in YNP, research will need to address other life-history stages to better understand population status.

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© Copyright 2020 David Brown Haines