Polar bears, black bears and grizzles found for first time together in rapidly warming North

A photo of a polar bear taken by a remote camera in Wapusk National Park. (Courtesy Doug Clark)

The appearance of grizzly bears in northern Manitoba challenges a lot of what the public thinks about conservation, a University of Saskatchewan researcher says.

Douglas Clark and his team are the first to document overlapping ranges of polar bears, grizzly bears and black bears. Since the observations were over the course of years and involved different bears, they know it’s not a one-off event.

“It challenges our assumption that change is bad. Well, maybe not all changes are bad,” said Clark, a conservation scientist at the School of Environment and Sustainability.

“To be really clear, it doesn’t mean this is entirely heralding good things for everybody – the area is warming pretty rapidly and polar bears are very vulnerable to that.”

The discovery is a “happy accident” stemming from a long term study on polar bear-human interactions on the coast of Hudson Bay, Clark said. In 2011 Parks Canada had built some field camps in Wapusk National Park inland from the bay to keep a safe distance from polar bears that live on the beach – but they kept seeing more bears than expected, so they called in Clark’s team to figure out that was going on.

The team set up remote cameras – an upgraded version of what hunters use to track white-tailed deer – and have tracked the polar bears over the past seven years.

The cameras also spotted grizzly and black bears in the park over the course of five years. One camera overlooking a beach ridge near some trees captured all three species in seven months – and even a black bear and polar bear within three hours of each other.

The bears each have their own ecological niche, Clark said. The grizzlies, the new arrivals, tend to be found on the tundra where they eat both caribou and berries, the latter of which appears to have become more abundant.

Polar bears mainly hunt seals on sea ice, though they’ll take the odd caribou, scavenge and nibble on berries further inland. Black bears stick to the forest, dining on berries, moose and caribou.

The big questions: what’s happening, and why now?

“It’s not simply that grizzlies were hunted out and now they’re coming back. What appears to be going on is some kind of environmental change. It’s a region of the world that’s warming really quickly, the environment is responding, we see changes in all kinds of animal and plant life, and this is a place where a bunch of ecosystems are found in pretty close proximity to each other,” Clark said.

“It’s right at the edge of the tundra and the forest and it’s right at the coast of Hudson Bay. So when things in the environment are changing, ecosystem edges can move and that’s what we’re seeing. It’s a really dynamic place.”

It’s possible that polar bears and grizzles could interbreed, a phenomenon documented in the Northwest Territories in early 2000s and which has happened repeatedly over hundreds of thousands of years in Alaska and Ireland, he said.

The team’s next step is for people in communities along the coast to set up the cameras to investigate what’s happening.

“People are used to dealing with polar bears up there. Polar bear-human conflicts are an issue, pile grizzly bear-human conflicts on top of that and people are kind of concerned.”

The findings have been published in the peer-reviewed journal Arctic Science.