new research suggests that it is a lack of food—not too-many or too-bold bears—that drives grizzlies into conflict with humans.
The increase in conflicts, though not statistically significant, might be explained by the continued presence of attractants or the social impact of the kills on other bears. Hunting had no impact on the frequency of conflicts.
“What we found challenges a common assumption in wildlife management, that killing bears is necessary to reduce conflict,” said lead author Kyle Artelle, a PhD candidate at Simon Fraser University and scholar at the Hakai Institute.
Data suggest that reduced food supply — especially when bears are feeding in advance of hibernation — is the driving factor behind conflicts between humans and grizzly bears, Artelle said.
Because conflicts between grizzlies and humans vary dramatically from year to year, the researchers were able to detect a striking pattern.
In areas of the province where bears normally have access to salmon in the latter half of the year, human-grizzly conflicts peak in years when spawning salmon returns are poor. Each 50-per-cent decrease in salmon abundance led to a 20-per-cent increase in conflicts with humans.
“In an ecological sense, that’s quite a strong association,” Artelle said.
Over the past 35 years, more than 80 per cent of conflicts have occurred when bears are eating heavily to fatten up for winter, even in areas where salmon is not available, suggesting that food availability is the main factor behind conflicts.
Grizzly attacks on humans — though rare — peak around the same time, said Artelle, who is also a biologist at the Raincoast Conservation Foundation.
“It has often been argued that we need to kill grizzlies in order to control their numbers and that would reduce human-bear conflicts, but there hasn’t been much research about whether that actually works,” he said. “Intuitively that would make sense because there are fewer bears to bump into.”
However, Artelle argues that killing a few individuals in the grizzly population would have little impact during a food crisis affecting the larger population. In fact, the data show that neither recent hunting kills nor conflict kills had a significant impact on conflict patterns.
Grizzly bear conflict kills have increased from fewer than 20 per year before 1990 to about 40 per year since and they are concentrated in the Northern Interior, Kootenays and Central Coast.
Conservation officers consider several criteria before destroying a large carnivore, including aggression toward humans and habitual reliance on human food sources, according to the B.C. Ministry of Environment. Relocation is not an option in those cases.
However, most human-bear conflicts will resolve themselves naturally, Artelle said.
Studies that tracked bears with radio collars have found that bears enter urban areas when food is scarce, but when food supplies improved those same bears would avoid humans.
“If you kill those conflict bears they won’t come back because they are dead, but if you don’t kill them, they still don’t come back,” Artelle said.
While it may be necessary to kill individual bears that prey on humans, killing conflict bears in general does not appear to be a sound management strategy, the study says.
The authors argue that restoring natural food supplies and allocating spawning salmon for bears in fishery plans could be an effective strategy for reducing human-bear conflict.