Spatial Ecology and Resource Selection of Bighorn Sheep (Ovis canadensis) Ewes in a Prairie Badlands Population

Authors

Erin Wood, University of Nebraska-LincolnFollow

First Advisor

John Benson

Second Advisor

Larkin Powell

Third Advisor

Elizabeth vanWormer

Date of this Version

Summer 7-31-2020

Document Type

Article

Citation

Wood, E. (2020). Spatial Ecology and Resource Selection of Bighorn Sheep (Ovis canadensis) Ewes in a Prairie Badlands Population. (Thesis). University of Nebraska-Lincoln, Lincoln, NE.

Comments

A Thesis Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor John F. Benson. Lincoln, Nebraska: July 2020

Copyright 2020 Erin Wood

Abstract

The basic spatial ecology and habitat relationships of female bighorn sheep in Nebraska are poorly understood. Establishing seasonal patterns of space use and resource selection for this population at the margin of their historical and current range addresses a key knowledge gap and provides important baseline information for ongoing conservation efforts in Nebraska. We deployed GPS radio-collars on 56 adult ewes in western Nebraska to quantify seasonal space use, movements, and resource selection of ewes. To investigate spatial ecology, we quantified movements of ewes and the factors that influence home range size, seasonal use, and spatial stability across seasons. Home range behavior and seasonal movements within this population appear to differ from others that have strong migratory tendencies. Multivariate modeling highlighted seasonal differences in space use and predicted a generally positive, non-linear relationship between home range size and road density. We also quantified resource selection patterns of female bighorn sheep within their home ranges and inferred factors that influence resource selection with a focus on predation risk, forage efficiency, and human disturbance. We used mixed-effects logistic regression with used and available locations for each individual to evaluate selection of topographical features, escape terrain, an index of high quality forage, and natural and anthropogenic landscape features. Ewes selected escape terrain, more rugged terrain, higher elevations, and water in all seasons. Selection of roads, development, and crops varied by season and subpopulation. Our work elucidates behavioral patterns of female bighorn sheep in Nebraska that may influence their survival and reproductive success. Our results should contribute to improved understanding of the factors limiting population growth for this declining population of conservation concern.

Advisor: John F. Benson