You are encouraged to attend the defence. The details of the defence and attendance information is included below:  

Date: June 16, 2025
Time: 10:00 AM to 12:00 PM (PT)

Defence mode: Hybrid
In-Person Attendance: Senate Chambers, UNBC Prince George Campus  
Virtual Attendance: via Zoom 

LINK TO JOIN: Please contact the Office of Graduate Administration for information regarding remote attendance for online defences. 

To ensure the defence proceeds with no interruptions, please mute your audio and video on entry and do not inadvertently share your screen. The meeting will be locked to entry 5 minutes after it begins: please ensure you are on time.  

Thesis entitled: NORTHERN MOUNTAIN CARIBOU (Rangifer tarandus caribou) DISTRIBUTIONAL RESPONSE TO HABITAT DISTURBANCE AND ALTERED PREDATOR-PREY DYNAMICS

Abstract: Northern mountain caribou (NMC; Rangifer tarandus caribou) range at the northern limit of expansive human-footprints in British Columbia. The southern extent of NMC range is threatened by habitat disturbance that has led to population decline and has forced caribou into small and isolated alpine areas. Human-caused habitat change is linked to increased predation risk through disturbance mediate apparent competition (DMAC). At the northern extent of NMC range in British Columbia, caribou freely range in large subpopulations in landscapes with minimal anthropogenic disturbance. The contrast between high- and low-disturbance landscapes offered a unique opportunity to study caribou distribution dynamics as they relate to habitat disturbance and subsequent DMAC. First, we used Bayesian stable isotope mixing models to understand the diet of wolf (Canis lupus) and grizzly bear (Ursus arctos horribilis), the two main predators of caribou and moose (Alces americanus), their apparent competitor. The caribou to moose ratio in wolf diet estimates appeared to be a reliable indicator of moose caribou abundance ratios. That analysis allowed us to determine if the diet of predators could serve as an index of the magnitude of DMAC between the two study landscapes. Second, we used this same contrast in disturbance to investigate the relationship between the distribution of GPS-collared caribou, habitat disturbance, and DMAC. Our results indicated that habitat disturbance influenced the magnitude of DMAC. We quantified a lower proportion of caribou relative to moose in the diet of wolves in the high-disturbance study landscape signalling the prevalence of DMAC. In contrast, we quantified a higher caribou relative to moose in the diet of wolves where anthropogenic habitat disturbance was relatively absent from the landscape, signalling no DMAC. We found a strong relationship between the distribution of monitored female caribou, disturbance, and DMAC. Seasonal home ranges were smaller and caribou used higher elevation habitats when they were confronted with relatively greater area of human disturbance. These two results are consistent with observations for other types of mountain caribou and indicate that habitat disturbance and DMAC cause range contraction. In total, our study suggests that increases in habitat disturbance will lead to continued range contraction for southern subpopulations of NMC and potentially instigate range contraction in the north. Thus, it is critically important to immediately consider ways to reduce habitat disturbance and proactively safeguard intact habitats across the range of NMC.

Defence Committee:  
Chair: Dr. David Connell
Supervisor: Dr. Chris Johnson
Committee Member: Dr. Heather Bryan
Committee Member: Mr. Conrad Thiessen
Committee Member: Dr. Doug Heard
External Examiner: Dr. Dale Seip