Blog: Exploring the Effects of Landscape and Climate Change on White-tailed Deer - and What They Might Mean for Caribou

Authors
Alberta Biodiversity Monitoring Institute
Resource Date:
2021

White-tailed deer populations are expanding in many areas across North America, sometimes leading to apparent competition with other species, like caribou. Essentially, larger deer populations mean more predators, such as wolves, and more predators mean more predation on all prey species—including ‘innocent bystanders’ like caribou. White-tail population expansion is influenced by many factors, including human land-use patterns and climatic effects, and understanding these factors can help managers mitigate the effects.

The Caribou Monitoring Unit team, led by MSc researcher Maud Laurent, estimated white-tail presence and density from nearly 200,000 ABMI camera trap images, and used models to relate it to snow-depth (a proxy for winter severity) and province-wide human footprint from the ABMI’s Human Footprint Inventory.

The results were in line with the team’s expectations but offered some surprises. Everywhere across Alberta, less snow was associated with higher deer presence, which lines up with seasonal deer movement patterns. On the other hand, more human footprint was associated with more deer in the north but not in the south, and the effect was especially strong for sites with relatively low human footprint to begin with. In other words, in relatively undisturbed habitats, such as those prevalent in the north, even small increases in human footprint may facilitate white-tailed deer expansion. 

So what does it all mean?  From a management perspective, these results suggest that restoring caribou habitat to nearly unaltered conditions may help to slow white-tail expansion, reduce predator densities, and, by extension, lower predation on caribou. This would be more feasible in northern areas because habitat there is, on average, less disturbed: the effort required for restoration is lower, and such actions might be expected to have a disproportionate benefit. But—and there’s always a “but”—the effectiveness of habitat restoration at restoring predator‐prey dynamics needs to be considered in the context of warmer winters due to climate change. Too warm, and the effect of habitat restoration might be diminished. Ultimately, other caribou recovery measures, such as predator and prey population management, will likely need to be considered along with habitat restoration.