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Topic

Understanding moose population declines in salvage-logged landscapes: Impacts of forest harvest on juvenile moose habitat use and survival, maternal strategies, and predator-prey interactions in interior British Columbia

School of Environmental Studies

Date & location

• Tuesday, March 25, 2025

• 8:30 A.M. 

• Clearihue Building, Room B021

• and Virtual Defence

Reviewers

Supervisory Committee

• Dr. Jason Fisher, School of Environmental Studies, University of Victoria (Co-Supervisor)

• Dr. Brian Starzomski, School of Environmental Studies, UVic (Co-Supervisor)

• Dr. Bradley Anholt, Department of Biology, UVic (Outside Member) 

External Examiner

• Dr. Eric Vander Wal, Department of Biology, Memorial University of Newfoundland 

Chair of Oral Examination

• Dr. Doug Magnuson, Department of Educational Psychology and Leadership Studies, UVic

   

Abstract

Understanding how anthropogenic disturbances compound with natural stressors to influence wildlife during vulnerable life stages is critical for conserving biodiversity and informing management decisions. Juvenile ungulates, including moose (Alces alces) are often sensitive to disturbances that alter resource availability and predation risk, potentially leading to population declines. Across interior British Columbia, moose populations declined concurrently with extensive salvage logging following insect outbreaks – but the causes of these declines were poorly understood. In this dissertation, I sought to tease apart the mechanisms underlying moose population declines by examining how moose recruitment is shaped by habitat use, maternal habitat selection strategies, and predation in landscapes undergoing drastic changes from forest harvest, with a focus on vulnerable 7-8 month old calf moose. In Chapter 1, I investigated how the habitat selection and movement of wolf (Canis lupus), one of the main predators of moose in this system, is influenced by the cumulative effects of landscape change, and how forest harvest features are tied to wolf kill-sites of moose. The combined selection and movement responses by wolves to logging features, coupled with increased moose mortality sites associated with cutblocks, indicate that landscape change increases risk for moose. In Chapter 2, I explored how recruited (i.e., surviving from 7-8 months to 1 year old) and non-recruited juvenile moose move and select natural and anthropogenic features, and how this is influenced by maternal proximity. I found that while recruited juveniles avoided habitats with elevated predation risk and energetic costs, non-recruited juveniles lingered in these unsafe habitats, which likely reduced their survival. In Chapter 3, I assess seasonal habitat selection, maternal body condition, and previous recruitment success of adult female moose in relation to their success in recruiting older calves. Successful females exhibited riskier behavior, which likely offset nutritional deficits from previous recruitment successes and winter tick loads. In Chapter 4, I investigated how forest harvest features and silvicultural treatments shape predator and ungulate distributions, and their interactions, based on wildlife camera trap data. Predator and ungulate occurrences, and their spatial relationships, were linked to silvicultural treatments, not only patterns of forest harvest. In Chapter 5, I examine how use of forest harvest features influences juvenile moose survival, and whether this mortality risk was modified by body condition, long-term use, forage availability, weather, or predation risk from wolves and black bears (Ursus americanus). I demonstrated that anthropogenic disturbances create risky landscapes for juveniles from predation and hunting, regardless of modifying factors, and in addition to natural stressors such as parasitism, reduce juvenile survival. Overall, I find that forest harvest increases juvenile mortality and contributes to moose population declines by altering wolf spatial distributions and hunting efficiency, increasing predation risk for juvenile moose lingering in high-risk cutblocks unlike their more experienced maternal females which benefit from using these habitats, reshaping predator and ungulate distributions and their interactions, and ultimately, creating risky landscapes that reduce juvenile survival.