Over twenty years of GPS collar data was used to understand where bears go and why in the southern Rocky Mountains
The southern Rocky Mountains provide a critical but narrow connection between grizzly bear populations in North America. To the east lie the prairies of Alberta and to the west, the settled valley of the Rocky Mountain Trench. Much of the southern Rocky Mountains are in national and provincial parks, though gaps remain in this protected network. Both in and outside of protected areas, major highways bisect valleys and towns sit in the low elevation valley bottoms.
Grizzly bears are well known for their large home ranges that often cover hundreds of square kilometres. This means that even in protected areas, bears have to navigate roads, highways, towns, and other human infrastructure. Outside parks, grizzly bears encounter even more — from logging and coal mining to large reservoirs built for hydroelectric dams.
Human development in the form of housing developments, traffic, and coal mining is increasing in the southern Rocky Mountains. Roads, towns, and industrial activity can change how bears move across the landscape, potentially isolating populations or increasing human-bear conflicts. Identifying important movement corridors and habitat patches—and barriers to their use—is essential to human-bear coexistence.
A new study used an impressive twenty years of GPS collar data from over 150 grizzly bears to understand their movements throughout 85,000 square kilometres of the southern Rocky Mountains. The researchers modeled bear movements and habitat selection in spring, summer, and fall, and used computer simulations to predict how bears change their movement behaviour in response to human developments such as roads and mines. This study brought together data and researchers across provinces and agencies to understand what bears do and why across this large and varied region. This work comes at a time when new developments and conservation plans are both on the table for the region.
“We had a unique opportunity to assess how bears move through the landscape and adjust their behaviour as local conditions change by using an incredible dataset collected over the past two decades. Although there are large tracts of well-connected grizzly bear habitats in the southern Rockies, we found that their movements are increasingly constrained by human development.” says Eric Palm, the postdoctoral researcher who led the research during his time at the University of Montana and the University of British Columbia.
Grizzly bears strongly avoided crossing highways, coal mines, large reservoirs, and towns. However, there were important differences between male and female bears. For example, males were more likely to use lower elevations and travel near towns in spring and summer. Females avoided roads and mines more strongly than males. Yet both were drawn closer to towns in the fall — likely attracted by fruit trees and other food sources such as garbage or livestock in rural and residential areas.
In general, when high-quality natural food was abundant, bears stayed away from roads. But in places where food was scarce, bears risked coming closer to roads to find it. Because both male and female bears avoided crossing major highways, these roads simultaneously fragment their habitat while drawing bears in with easy food that exposes them to danger.
The study found that existing human development has reduced connectivity between habitat patches compared to historical conditions. Looking ahead, the researchers used computer models to simulate future development. They found that additional development in this landscape would reduce habitat connectivity, with developments in “core” grizzly bear habitat having outsized impacts compared to developments on the periphery of their current range.
“Grizzly bears in the southern Rockies have to travel through a mix of wild lands and human development during their lives,” says Clayton Lamb, senior author and Biodiversity Pathways wildlife scientist. “This study shows how roads, towns, and mines can fragment their habitat and change where bears go and when — but it also highlights actions that can be taken to keep these areas connected and safer for both people and bears.”
Large-scale studies like this are vital. They show where bears live and move — and what stands in their way. The results highlight solutions to co-exist: maintaining high-quality wild habitat, building safe wildlife crossing structures on highways, and managing attractants in towns — like removing fruit trees or garbage that lure bears into risky areas.
Funding partners: This research was supported by Yellowstone to Yukon Conservation Initiative, Canadian National Program for Ecological Corridors, Nature Conservancy of Canada, Elk Valley Regional Land Trust, Habitat Conservation Trust Foundation, Wilburforce Foundation, and the Aldo Leopold Wilderness Research Institute.
Contact Clayton Lamb, Wildlife Scientist, with any inquiries.