Isabel Giguere

Topic

Intrinsic and extrinsic drivers of Columbian black-tailed deer population dynamics

School of Environmental Studies

Date & location

• Wednesday, December 10, 2025

• 1:00 P.M.

• David Tuprin Building

• Room B255

Reviewers

Supervisory Committee

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

• Dr. Brian Starzomski, School of Environmental Studies, UVic (Member) 

External Examiner

• Dr. Chris Darimont, Department of Geography, University of Victoria 

Chair of Oral Examination

• Dr. Kieka Mynhardt, Department of Mathematics and Statistics, UVic

   

Abstract

Anthropogenic landscapes fragment and reshape habitat for terrestrial mammals, favoring some species over others, triggering population shifts with cascading ecological impacts. In North America, Columbian black-tailed deer (Odocoileus hemionus columbianus; BTD) contribute to biodiversity loss, seen with both abundant urban and declining wild populations. Effective wildlife management is limited by poor understanding of how extrinsic forces influence intrinsic drivers, such as reproductive success - the key determinant of population persistence in deer. To address this gap, we studied two populations of immunocontracepted (IC) BTD on southern Vancouver Island, British Columbia, to assess how dispersal barriers and habitat quality influence the spatiotemporal dynamics of reproductive success. Using multi-year camera-trap data, we compared reproductive trends across two systems differing in permeability - one constrained by dispersal barriers and one permeable to immigration. We further examined how forage quality and cover shaped habitat selection by mothers (does with fawns) and non-mothers (does without fawns). The permeable system exhibited source-sink dynamics, where immigration drove increases in reproductive output; mothers selected energetically optimal features with nutrient-rich forage and cover, while non-mothers selected nutrient-poor, exposed and risky features. These results demonstrate how extrinsic landscape features can shape intrinsic processes like reproduction, generating temporal variation in IC effectiveness and spatial segregation among demographic groups. Integrating empirical insights from applied management with ecological theory can inform coexistence strategies for large mammals in increasingly human-dominated environments.