The continuing climate crisis could be having an unexpected effect on Arctic wildlife, with rising temperatures causing an overlap between the hunting grounds of two of the region’s apex predators, polar bears and grizzlies. The bears, however, appear to be lovers not fighters, and are not afraid to dabble in a bit of “opportunistic mating”, producing the curious polar-grizzly hybrid known as a “pizzly”.
Unfortunately, this isn't a furry case of "Life, uh, finds a way" but a reminder of the effects of the human-caused climate crisis on the animal kingdom.
Arctic climate change poses a serious threat to polar bears (Ursus maritimus) as warming temperatures reduce sea ice, and reduced sea ice means fewer opportunities to prey on juicy resting seals. This is pushing polar bears, which are particularly adapted to a diet of high-fat blubber and meat, further south out of their hunting zone in search of food, potentially altering their diets and consuming foods they are not well suited for, according to a study published in Global Change Biology.
Warming temperatures, on the other hand, are pushing grizzly bears (Ursus arctos) north, making them more likely to come into contact with polar bears.
“We’ve known about pizzlies for quite some time, but their occurrence may be more common with ongoing Arctic warming,” explains Larisa DeSantis, associate professor of biological sciences at Vanderbilt University and co-author of the study, in the video below.
We have indeed known about pizzly bears for while. In 2006, hunters shot a white bear sporting brown patches, and DNA confirmed that it was a pizzly. There have also been incidences of second-generation hybrids. Ulukhaktok airport in Canada's Northwest Territories famously greets visitors with a stuffed pizzly that is 3/4 grizzly and 1/4 polar bear. In 2017, a study traced eight known pizzlies back to one female polar bear that had mated with two grizzly bears.
As DeSantis says in the video, the two species are capable of reproducing offspring that are themselves capable of reproducing (most hybrids are sterile) because the two species only diverged around 500,00- 600,000 years ago. Whether the pizzly population will actually increase is yet to be seen, as both bear species have adaptations best suited for their habitat. However, DeSantis points out, there have been examples of where hybrids have been better able to adapt to a particular environment, "particularly if that environment is deviating from what it once was."