Tag Archives: range expansion

Grizzly spotted on Western Hudson Bay shore but there are no polar bears on land for it to mate with

On 28 May last week a big grizzly (probably a male) was spotted on the shore of Wapusk National Park just south of Churchill, Manitoba but unless he heads out onto the sea ice, he has no chance of finding a polar bear female to mate with. Even if he does, he is unlikely to find a polar bear female willing to mate: most polar bears mate late March to early May (Smith and Aars 2015). Brown bears (called grizzlies across most of North America) mate later in the year, from late May to July, which means finding hybrids here is highly unlikely.

A few tundra grizzlies from the Northwest Territories have been spotted moving southeast into the Hudson Bay area since 2008. There was some media-and-expert-generated excitement back in 2016 when a hunter shot what he thought might have been a grizzly/polar bear hybrid near Arviat but it turned out to be a blonde grizzly, which are not uncommon in the tundra population from which it came. A similar result came from recent genetic study: samples from two pale blonde grizzlies from the North Slope of Alaska that looked remarkably like polar bear hybrids were not only unrelated to each other but showed no evidence of being hybrids (Lan et al. 2016 Supplementary data, pg. 3).

Contrary to some predictions, grizzly/polar bear hybrids are still quite rare (Crockford 2018:23).

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Another alleged grizzly-polar bear hybrid shot but it’s not a sign of climate change

CBC News this morning (“Grolar or pizzly? Experts say rare grizzly-polar bear hybrid shot in Nunavut: Expert says interbreeding may be happening more frequently due to climate change“) suggests that a putative grizzly x polar bear hybrid bear shot outside Arviat in Western Hudson Bay is a sign of climate change, based on an interview with a black bear expert from Minnesota.

Hybrid pb shot in Arviat_CBC 18 May 2016

This bogus claim has been busted so many times it’s a wonder it still arises – even polar bear specialist Ian Stirling has said flat out that such hybrids are not due to climate change. On top of that, some of the details regarding this putative hybrid make me want to wait for confirmation from DNA testing before adding it to the roster of known hybrids.
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