The Columbia River Basin of British Columbia is home to the Columbia North, Frisby-Boulder and Columbia South caribou ranges. These areas are known for their deep snow and steep terrain. Caribou navigate these areas, keeping above the snow with their large hooves to access arboreal lichens.

In recent history, human activities like forestry have changed the landscape drastically. As a result, the mature old-growth coniferous forests have shifted towards younger, deciduous-dominated forests, that favor ungulates like moose. Areas with more young forests and moose therefore sustain higher predator populations than what would otherwise thrive there. As a result of the changes to the food web in the Columbia River Basin, caribou herds are facing unsustainably high predation rates, leading to declines. Southern Mountain Caribou are listed as Threatened under the Species are Risk Act.

Changes to the landscape are also leading to the expansion of white-tailed deer into the region. White-tailed deer were first found in the study area in 1986, and are an important food source for predator populations. Young forests create an abundance of early-seral forage, and winters are becoming less severe with climate change – both of these spell good news for deer.

How white-tailed deer population dynamics influence the predator-caribou system, and how management actions might be able to address these issues, has yet to be evaluated. Understanding white-tailed deer population dynamics within the Columbia region will become important as caribou management continues to unfold, and as climates continue to favor the northward expansion of white-tailed deer. It is particularly important to understand how white-tailed deer populations are responding to the reduction of wolves and cougars in the region.

Beginning in 2019, 17 white-tailed deer does were captured and outfitted with GPS collars to estimate survival and cause-specific mortality. Concurrently, 8 mule deer does were captured and monitored. As of 2022, the 3-year mean annual survival rate of white-tailed does was estimated to be 0.71, whereas mule deer survival was 0.80. Vehicle collision and predation (by coyotes, cougar, and potentially wolverine) were the leading cause of death. Continued monitoring of captured deer will improve the accuracy of survival estimates and provide an understanding of trends in annual survival rates and cause-specific mortality. With the addition of a pilot wildlife camera program, we hope to combine camera-trap data and GPS-collar data to monitor population trends.

This project will inform the missing knowledge of how white-tailed deer populations contribute to increased abundance of wolves and cougars within SMC range. These results will have direct implications for the long-term effectiveness of predator and prey reduction programs in British Columbia.

Acknowledgements:

Funding for this project has been provided by the Fish and Wildlife Compensation Program, Habitat Conservation Trust Fund, the Government of British Columbia, and Environment and Climate Change Canada.

The support of Splatsin of the Secwepemc Nation and the Revelstoke Rod and Gun Club has been instrumental to the program’s success.