Grizzly Bears and Resource-Extraction Industries: Effects of Roads on Behaviour, Habitat Use and Demography

Abstract

(1) Roads are an integral part of the development of resource-extraction industries. We wanted to know whether grizzly bears [Ursus arctos] were displaced by these roads from adjacent habitats. Over 7 years, twenty-seven grizzly bears were captured and radio-collared in 264 km2 of the Rocky Mountains, containing active tree-felling and petrocarbon developments. (2) Most bears used habitats within 100 m of roads less than expected. This is equivalent to a habitat loss of 8.7%. This is significant because many habitats close to roads contain important bear foods. Avoidance of roads was independent of traffic volume, suggesting that even a few vehicles can displace bears. (3) Roads and nearby areas were used at night but avoided in the day. Yearlings and females with cubs used habitats near more than other bears. These areas may have been relatively secure because they were avoided by potentially aggressive adult males. (4) Limited data indicated minimal demographic effects during our study, but roads increased access for legal and illegal hunters, the major source of adult grizzly mortality. (5) When roads are developed for resource industries in grizzly bear habitat, the bear population becomes highly vulnerable unless vehicle access and people with firearms are controlled.