Year of Award
Doctor of Philosophy (PhD)
Fish and Wildlife Biology
Department or School/College
College of Forestry and Conservation
Rich Harris, Mark Hebblewhite, Kevin McKelvey, L. Scott Mills, Katherine C. Kendall
University of Montana
Understanding how environmental factors influence wildlife populations is at the heart of ecology and management. Populations and their habitats are, however, inherently dynamic, which requires monitoring responses to changes in the environment. Beyond quantifying population dynamics, understanding why populations respond as they do may allow improved predictions within and across populations, ideally leading to better management. Grizzly bears (Ursus arctos) and American black bears (U. americanus) have been researched in North America for decades, providing excellent opportunities to explore ecological questions involving inter- and intraspecific competition and responses to spatial and temporal variation in resources. The wealth of data collected on these species may be used to answer ecological questions and obtain reliable information for monitoring and management in a rapidly changing world.
Chapter 1: Why do grizzly and black bear densities vary in space and time? I used data from noninvasive genetic sampling of grizzly and black bears in northwestern Montana with spatially-explicit capture-recapture models to predict sex-specific density patterns for both species. In addition to intraspecific effects on density, I considered biotic and abiotic factors such as net primary productivity and habitat security.
Chapter 2: Why do detection probabilities of grizzly bears at bear rubs vary within and across populations? Research has shown detection to vary by sex and season, but also across populations. I used data from two large noninvasive genetic sampling studies to explore a suite of biotic and abiotic factors that are plausibly related to bear rubbing behavior. After creating predicted density surfaces for both species, I competed models including effects of density, terrain characteristics, and sampling effort in mark-recapture models to evaluate support for my hypotheses.
Chapter 3: Monitoring the performance of any wildlife population can be difficult, and the variety of research tools to do so can be overwhelming at times. To assist black bear managers across northeastern North America in identifying suitable tools, I assessed the tradeoffs of methods including traditional mark-recapture, spatially-explicit methods, and known fate models. For some methods, I also conducted simulations based on published data to provide insights into study design and expectations of model performance.
Stetz, Jeffrey Brian, "EXPLAINING AND MONITORING POPULATION PERFORMANCE IN GRIZZLY AND AMERICAN BLACK BEARS" (2017). Graduate Student Theses, Dissertations, & Professional Papers. 10984.
© Copyright 2017 Jeffrey Brian Stetz