Grolar bears: Climate change upping number of grizzly and polar bear hybrid 'pizzlys'

The killing of a grolar bear – a hybrid of a polar and grizzly bear – has led experts to say climate change will lead to increasing numbers of the creatures (also known as pizzly bears). Researchers say global warming will lead to the two species crossing paths more often, which will result in lots more pizzly and grolar bears being born.

Hunter Didji Ishalook killed the bear on Hudson Bay in Canada, a region that is home to both polar and grizzly bear populations. Initially, he thought he had shot a female polar bear. However, closer inspection showed it had features of a grizzly, with the coat of a polar bear.

"It looks like a polar bear but it's got brown paws and big claws like a grizzly. And the shape of a grizzly head," he told CBC News. "It turned out to be a grizzly half-breed."

Bear expert Dave Garshelis, from the Minnesota Department of Natural Resources, said the colouration of the bear's claws, nose and eyes shows it is a hybrid, rather than an albino grizzly. "An albino bear would have a light-coloured or pink-coloured nose, and no pigmentation in the eyes and the claws," he said. "This bear has a black nose, and normal dark-coloured eyes and claws. So, it's not an albino."

More overlap between polar and grizzly bears

Grolar (where the father is a grizzly) and pizzly bears (where the father is a polar bear) were first confirmed as a hybrid species in 2006 through DNA testing of a specimen shot in the Canadian Arctic.

In 2010, US researchers confirmed grizzly bears were increasingly being found in areas of Canada traditionally populated by polar bears. Whether this shift in habitat was a result of climate change was not known, however.

While further evidence will be needed to attribute the change to global warming, Grashelis believes this is the cause of the increasing interaction – and interbreeding – between the two species.

"With climate change, grizzly bears are moving further north, so there is more overlap between grizzly bears and polar bears in terms of their range," he told CBC. "There are even American black bears that are moving further north."

Chris Servheen, a grizzly bear expert from the University of Montana, also told the Guardian: "The combination of warmer temperatures and vegetation growth means there is more overlap between the species and I'd expect that overlap to increase. We didn't see it much in the past but we are now. The two species are very similar genetically so males of both species will be attracted to females, which is why we are seeing a mix-up in the breeding."