Intrinsic and extrinsic drivers of Columbian black-tailed deer population dynamics
Date
2025
Authors
Giguère, Isabel
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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.
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Keywords
Population dynamics, Population control, Wildlife management, Immunocontraception, Urban deer, Habitat selection, Reproduction, Human-wildlife coexistance, Urban ecology, Black-tailed deer, Columbian black-tailed deer, Camera trapping, GIS, Vancouver Island, Odocoileus hemionus columbianus, British Columbia, Immigration, Animal marking