Year of Award

2018

Document Type

Thesis

Degree Type

Master of Science (MS)

Degree Name

Wildlife Biology

Department or School/College

Wildlife Biology Program

Committee Chair

Mike Mitchell

Commitee Members

Dr. Thomas Stephenson, Dr. Mark Hebblewhite, Dr. Paul Lukacs, Dr. Creagh Breuner

Keywords

Sierra Nevada Bighorn sheep, neonate, predation, resource selection function, juvenile recruitment, mountain lion

Publisher

University of Montana

Subject Categories

Behavior and Ethology | Genetics | Integrative Biology | Other Ecology and Evolutionary Biology | Population Biology

Abstract

Long-term viability of endangered populations requires development of effective management strategies that target the population vital rate with the highest potential to influence population trajectories. When adult survival is high and stable, juvenile recruitment is the vital rate with the greatest potential to improve population trajectories. For my thesis I examined how lactating Sierra Nevada Bighorn sheep (Ovis Canadensis sierra) balance forage and predation risk during the neonatal period. I first identified resource selection strategies employed by lactating females to promote survival of neonates and then determined the primary factors affecting survival of neonates. I found lactating females selected for habitat reduced the risk of predation by mountain lions. Understanding the availability of high quality neonate rearing habitat is an important consideration in restoring bighorn populations. My predictive resource selection function models will assist managers in identifying habitat that is most likely to meet the lambing needs of lactating bighorn females. I also found that despite the efforts of lactating female to protect neonates from risks of predation, predation was the strongest factor contributing to variable survival of neonates across subpopulations. I determined that neonates become less vulnerable as they age, were most vulnerable if they were born before the peak birth pulse (April) and if lactating females selected habitat farther from the safety of escape terrain. My work is the first to examine factors affecting selection of neonatal habitat by lactating females and survival of neonates within Sierra bighorn sheep populations. My results have elucidated potential management strategies that may inform recovery actions.

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© Copyright 2018 Shannon Forshee