The Elk Valley in southeastern B.C. has developed into an "ecological trap" where a high number of grizzly bears are getting killed on roads, on railway tracks and in conflict with humans, new research has found.
"In the last eight years we've lost 40 per cent of our grizzly bears in that area – that's not normal," says Clayton Lamb, a PhD candidate at the University of Alberta and lead author on the study.
In the past, some of the highest grizzly bear densities in North America have been found in the region. But Mr. Lamb says the data collected in the study show the grizzly population is in steep decline because of human activities.
While hunting is a factor, 68 per cent of grizzly bear deaths in the Elk Valley are from non-hunting causes.
"Within the non-hunting [category], over half is due to the roads and the rails," Mr. Lamb said.
The research paper states that 54 per cent of the non-hunting deaths were due to collisions with vehicles and trains, 33 per cent were due to human-bear conflicts, such as problem animals being shot in urban areas or by ranchers, and poaching accounted for 13 per cent of the bear mortality.
Mr. Lamb said the statistics are troubling because while hunting can be controlled through simple regulatory changes, it is more difficult to mitigate the other causes.
His study also found that when grizzly bears are killed in the Elk Valley, more bears from surrounding wilderness areas soon move in to replace them. The result is that bear populations have declined over a large area beyond the Elk Valley.
"What we found was in the [Elk Valley] trap there was really high mortality and the bears suffered. They had low survival rates in that area," said Mr. Lamb. "[But] we found that as grizzly bears were being killed in the trap, individuals from the back country would then move into the trap to backfill the holes that were caused by that mortality. So you essentially had this flow of back country bears into the front country."
About 12,000 people live in the Elk Valley, which contains the towns of Fernie and Sparwood and is surrounded by the southern Rocky Mountains. Several highways, with traffic volumes of more than 18,000 vehicles a day, and many secondary roads run through the region, as does a Canadian Pacific Railway line.
Mr. Lamb said a lot of the bears from which DNA samples were collected early in the study were dead by the time the research was completed.
He said grizzly bears and other large carnivores select their habitats using cues. In the Elk Valley, rich berry crops have caused the bears to identify the region as an attractive habitat, and they are drawn there instinctively. But long after the bears adapted to living in the valley, humans moved in and, in a relatively short time frame, altered the habitat dramatically through development.
The bears continue going to the area despite the great dangers to their survival posed by the relatively recent human activities.
Mr. Lamb said if the decline of bears is to be reversed, people will have to figure out ways to reduce human-carnivore conflict.
His continuing research is aimed at finding such solutions. This week he is in the region trapping and putting radio collars on grizzly bears so he can track their daily movements.
"We are trying to understand, at the scale of the individual … how are they using the habitat, where exactly are they dying and what is the mechanism of that death?" Mr. Lamb said. "We hope to provide some mitigation so we can address this because the problem seems to be ongoing because we've had five grizzlies killed in the last month. So we are kind of living it right now."
Mr. Lamb is a Vanier Scholar in the University of Alberta's department of biological sciences. His paper, with co-authors Garth Mowat and Bruce McLellan of the B.C. Ministry of Forests, and Scott Nielsen and Stan Boutin of U of A, is published in the Journal of Animal Ecology.