Grizzly bear populations remain at risk
Grizzly bears are doing their best to get along with people, but it still isn’t enough.
Newly published research concludes that without large wilderness areas to replenish their numbers, grizzlies would disappear from landscapes they share with humans.
“The persistence of bears near people, when we see them along highways or near towns, they’re really propped up by the fact they exist near some sort of secure wilderness,” said Clayton Lamb, a University of Alberta biologist and lead author of a paper published in the Proceedings of the National Academy of Sciences.
Researchers found bears in populated areas in Alberta and British Columbia have even changed how they hunt in an attempt to share living space with humans.
The study set out to examine an emerging phenomenon in wildlife conservation — large carnivores re-establishing themselves on mixed landscapes including cities, highways, rural communities and patchworks of natural habitat.
It digested 41 years worth of mortality, movement and demography among 2,669 grizzlies over nearly 400,000 square kilometres of British Columbia.
It found mortality has increased steeply with the amount of human impact measured through an index that includes human population, land use, infrastructure, coastlines, roads, railroads and navigable rivers.
Deaths have outnumbered births and the difference is being made up through emigration of young grizzlies from nearby wilderness. For every point the index increases, a local bear population must increase the number of individuals it draws by about two per cent.
“Grizzly bear range is quite tied to the distance from some secure piece of wilderness,” said Lamb.
That’s despite the grizzlies’ efforts to adapt to humans. The study found young, newly arrived bears gradually learned ways to avoid contact, such as hunting and gathering at night.
Adolescent bears in areas dominated by humans have increased their nocturnal time by up to three per cent annually, which has led to corresponding increases in survival.