Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Biology

Program Name/Specialization

Integrative Biology

Faculty/School

Faculty of Science

First Advisor

Frances Stewart

Advisor Role

Supervisor

Second Advisor

Brad Woodworth

Third Advisor

Scott Ramsay

Abstract

Northern ecosystems are experiencing a period of rapid and unprecedented change, with implications for species distributions, mammal community dynamics, and habitat associations. Understanding the ecological processes that shape species distributions is crucial for developing effective conservation strategies that can adapt to such change. This study examines drivers of barren-ground caribou occurrence, a species of cultural and ecological significance, across Thaıdene Nëné Indigenous Protected Area, an ecologically intact landscape of high habitat heterogeneity straddling the treeline of the Northwest Territories. I use spatial and temporal variation in caribou detections generated by camera traps to test the relative importance of apparent competition, top-down, or bottom-up ecological processes across biologically relevant seasons and areas of varying environmental heterogeneity. This is accomplished by regressing weekly detections of caribou against habitat covariates and/or the occurrence of heterospecific ungulates and their shared predators using generalized linear mixed models, each representing a specific ecological process and scale. As predicted, my results suggest this is a primarily bottom-up driven system. Caribou were negatively associated with taiga-type landcovers across all seasons regionally and showed more varied habitat associations locally. I found evidence for a localized seasonal shift in the relative importance of ecological processes, where top-down pressures exerted by gray wolves were the dominant driver of winter caribou occurrence. The hypothesis-based models used in this study failed to adequately explain spring caribou occurrence at the local spatial extent, suggesting unmeasured or no ecological processes govern caribou detections at that spatiotemporal scale. Future work could consider traditional knowledge and additional ecological variables (e.g., movement facilitation, insect harassment) to further refine spatiotemporal models of caribou occurrence. Effective caribou stewardship must be adaptive and context-sensitive, identifying when and where key ecological processes exert the strongest influence on the species. By determining the contexts in which bottom-up and top-down processes dominate across different spatiotemporal scales, this research can help inform management strategies within Thaıdene Nëné and contribute to broader ecological theory regarding the drivers of species distributions.

Convocation Year

2025

Convocation Season

Spring

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