This is why grizzly bears are becoming nocturnal

Published: July 23, 2020

Grizzly Bear in Banff, Alberta BGSmith

Spend enough time cottaging in the forests of Canada, and it’s likely you’ll accrue a story about a bear. From rounding a corner on a trail and coming face-to-face with a grizzly bear, to a nighttime visit from a curious black bear that has followed their nose to your greasy, uncleaned barbecue grill, the thrill of an encounter with these intelligent carnivores provides cottagers with once-in-a-lifetime stories to be shared around campfires. But these meetings can be problematic for both people and bears.

Researchers have found that grizzly bears in human-dominated areas of British Columbia are adopting nocturnal lifestyles to avoid people. But this change isn’t enough to sustain their populations. Immigration of individuals from wilderness landscapes is what allows bears to persist in areas with human settlements. This delicate balancing act provides clues to how people and bears can change their behaviour and live peacefully alongside one another. 

According to Clayton Lamb—postdoctoral researcher with the Universities of British Columbia and Montana and lead author of the research—a wildlife “conflict” is any speed bump on the way to peaceful co-existence with people. Conflicts can range from a bump-in with a grizzly bear on a trail, to a bear walking away from a campsite with a cooler of food. It is much more unusual to have a physical encounter with a bear. In incredibly rare encounters, conflicts may end in a human fatality. 

Conflicts aren’t good for bears, either. Conservation authorities dealing with a problematic bear that has become dependent on human sources for food, or acts aggressive towards people, may choose to destroy the bear. 

Lamb and his colleagues found that 80 per cent of bear mortalities can be attributed to people, even in wilderness areas. “The majority of bears end up dying in the hands of people,” he says. The difference is that it happens much sooner when bears live close to humans.

A little bit of natural history can also explain why grizzly bears are recognized in the study as one of the world’s most conflict-prone carnivores. Bears only have five to seven months a year to find food, says Lamb. The rest of the time they’re in the den. Because they’re racing the clock, they’re dependent on finding food in the summer and fall in a way that other large carnivores, like wolves and cougars, aren’t. “Because they have to gather those calories, they take risks and trade off their survival in the short-term to make they sure they can make it through the winter,” says Lamb.

Historically, grizzly bears were found eastwards across the plains of Canada into Manitoba, says Lamb. While forest-homes provided black bears with trees as escape routes, grizzly bears didn’t have cover when danger approached. Their survival strategy is unchanged: stand and face the danger, says Lamb. “On the flight and fight spectrum, they’re on the fight spectrum.”

So what brings a grizzly bear to the human-filled areas of British Columbia? “Bears disperse naturally,” says Lamb. Young bears can travel 100 kilometres in search of a new home when they leave their mother. A young bear may find itself in a human-populated area with lots of food available: roadkill, apple orchards, hunter’s scraps. On the plus side, these landscapes tend to have very few other bears to compete with. “It’s pretty hard as an individual to perceive that there’s a problem,” he says.

Lamb and his team found that as bears aged they were shifting to a nocturnal routine to reduce conflicts with people. “Unfortunately, a lot of these animals end up dying before they can figure out how to live down there in the valleys,”  he says. They found that it takes 14 years for a bear to become a successful co-existor in rural areas, meaning their survival rates are similar to adult bears in wilderness areas. But for every bear that lives to 14, about 29 other area bears will die. As he explains, “females were not producing enough cubs to offset the ones that were dying.”

As long as bears continue to move from wilderness areas to rural ones, the bear populations in human-dominated areas can remain steady. “It’s a real bittersweet kind of thing,” says Lamb. “We’re seeing bear populations actually expand into human areas,” he says. “At a large scale, it’s working. It doesn’t mean it’s a good outcome for those individuals.” He stresses that grizzly bears can only continue co-existing in human areas by adapting nocturnal lifestyles if connections for immigrating bears from wilderness areas remain strong.

How can cottagers and other residents of bear-populated areas promote a peaceful co-existence with bears? Lamb says you must eliminate or block attractants that draw hungry bears to your home, such as fruit trees, garbage, livestock, and hunter scraps. He recommends that if you have a property with a permanent attractant, like an apple orchard, that you install an electric fence. Better the bear gets a shock and moves on, than face the consequences of a human-bear conflict. 

He also says it is important to maintain the integrity of wild areas and improve connections between landscapes. He points to Banff, which reduced individual morality of bears and improved connections between wilderness areas all in one when they installed fences and built large overpasses for animals to safely cross highways. These actions also benefit people, as no one wants to hit a bear, or deer, or elk, on their drive, he adds. It is through “finding these innovative win-win solutions,” Lamb says, that people can co-exist with grizzly bears.

Read more: White grizzly bear sighting in Banff National Park sparks wildlife safety concerns

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