For the first time, scientists have looked at three species of American bears – the black bear, the polar bear and the brown bear – using the same habitat in Wapusk National Park, Canada.
"Scientifically, it has never been documented anywhere," said Doug Clark of the University of Saskatchewan,
Using remote cameras, Clark and his team of researchers documented 401 bear visits of all three species (366 of polar bears, 25 of black bears and 10 of brown bears) in three camps in the national park of 2011-2017. The results were published this week in the journal Arctic Science.
The presence of polar and black bears was not uncommon. After all, Wapusk National Park houses one of the largest maternity areas in the world for polar bears. The park is also north of a forested region where black bears call home.
It was the number of visits from grizzly that was the biggest surprise.
"These observations contribute to an increasing body of evidence that brown bears are experiencing a substantial increase in northern Canada, and the timing of our observations suggests local deforestation," the authors write.
Clark delved deeper into the study in an essay for The Conversation:
Three dynamic ecosystems – forest, tundra and ocean – converge on Wapusk, and everyone is changing rapidly
as the Arctic warms.
What we saw in Wapusk is consistent with how researchers expect northern carnivore populations to respond to climate change.
The study adds further evidence that grizzly bears are appearing in places where they are not normally found. Other scientists have suggested that the rise in occurrences of so-called "pizzly" or "grolar" bears – or brown-polar hybrids – is the result of brown bears in Alaska and Canada expanding north due to the heated environment, bringing them in contact with polar bears.
"The combination of higher temperatures and vegetation growth means there is more overlap between species and I would expect the overlap to increase," Chris Servheen, a specialist in brown bears at the University of Montana, told The Guardian in 2016.
It is not clear whether the three species of bears are interacting with each other, or what effect their combined presence has on the larger environment.
"How they interact is a really big issue," Clark told the Canadian Press. "There are all sorts of things that can go on."
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