Year of Award

2021

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Wildlife Biology

Department or School/College

W.A. Franke College of Forestry and Conservation

Committee Co-chair

Angela D. Luis, Mark Hebblewhite

Commitee Members

Paul M. Lukacs, Jon S. Horne, John L. Maron, J. Joshua Nowak

Abstract

Large carnivores are re-colonizing their historical range globally, following decades of systematic eradication. The subsequent expansion of large carnivore populations is creating complex predator-prey interactions by trophically upgrading previously simpler food webs. Overlap between large carnivore and human range expansion is increasing human-carnivore conflicts, with many calling for large carnivore management to mitigate predation on harvested ungulates. However, the complexity of food web interactions in trophically upgraded systems coupled with independent management strategies for each species makes it difficult to determine what are optimal management strategies in these systems. These issues are further complicated by expectations of harvested ungulate densities based on historical baselines. By ignoring these issues, agencies could be sub-optimally preserving and managing wildlife populations.

In this dissertation, I used theoretical modelling and real-world data to evaluate the effects of large carnivore recolonization on population and community dynamics and the efficacy of predator management in the Rocky Mountains. I found that large carnivores and ungulates are capable of nonlinear, complex dynamics and that carnivores can shift prey populations between alternative stable states through predation. I then used a global meta-analysis of predator control experiments and found that predator management had positive, yet uncertain effects on ungulate populations. Following the evidence of complex dynamics in predator-prey systems, I developed an integrated community model (ICM), a Bayesian hierarchical model that integrates multiple data sources for multiple species to expand inference to the community-level. I used these ICMs to explore the effects of harvest management in trophically upgraded systems in Idaho. I found that predators can hold prey to lower, stabler populations and that predator harvest could reverse these stabilizing effects. I then used ICMs to explore optimal management, finding that managing for high ungulate populations in these systems could necessitate either long-term predator management and significantly reduced ungulate harvest.

In summary, my findings suggest that large carnivore recolonization will reshape predator-prey communities in the Rocky Mountains, and that conflict may increase due to the difficulty of managing for elevated ungulate populations. I suggest that further research into predator-prey management as a socio-ecological, not just biological problem, may help resolve increasing conflict in the Rockies and elsewhere.

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© Copyright 2021 Tyler James Clark