As the planet has warmed, grizzly bears have expanded their territories further north, while the endangered polar bears, thin and starving, have been driven further south, in search of food.
The two species of bears – intermingling as their territories overlapped – has resulted in strange, hybrid bears popping up in the colder reaches of North America.
With features that could give them an edge in warming northern habitats, some scientists speculate that the pizzlies, or “grolars”, could be here to stay, Larisa DeSantis, a paleontologist and associate professor of biological sciences at Vanderbilt University in Tennessee, told Live Science:
“Usually hybrids aren’t better suited to their environments than their parents, but there is a possibility that these hybrids might be able to forage for a broader range of food sources.”
She went on to explain that polar bears have a longer skull that aids them in grabbing seals out of the ocean, “But their molars are smaller than is typical for their body size because all they eat is blubber all day. Grizzlies, on the other hand, can eat whatever they want. We don’t know yet, but perhaps the intermediate skull of the pizzly could confer a biomechanical advantage.”
A rare animal, indeed
It has only been about 500,000 to 600,000 years since polar bears and grizzlies went their separate ways, reports Nature World, so the two species can mate and give birth to viable young. Research and study of the hybrid animals in the wild suggest that the hybrids are very fertile and have also produced offspring.
Sightings of the hybrid bears began in 2006 when a hunter shot what he thought was a polar bear in the Northwest Territories of the Canadian Arctic. On closer inspection, he discovered a more uncommon animal.
The bear did have the creamy white fur typically seen on a polar bear, but it had the humped back, long claws, and hallow face of a grizzly bear, along with some brown patches of hair. DNA tests were done and confirmed the bear was a polar-grizzly hybrid.
Since that time, sightings of the pizzly bears has increased in number, with a 2017 study noting a single female polar bear who mated with two grizzly bears ended up producing a total of eight offspring over the course of several years.
Interestingly, the rise in the number of pizzly bears has coincided with the decline in the number of polar bears. Their numbers are predicted to decline by over 30 percent in the next 30 years, as stated by a 2016 study in the journal Biology Letters.
What does this all mean? “We’re having massive impacts with climate change on loads of species right now,” DeSantis said. “The polar bear is the canary in the coalmine telling us how bad things are.”
In some sense, pizzly bears could be a sad but necessary compromise given current warming trends, DeSantis said. “Apex predators help stabilize ecosystems, and looking forward I really hope the Arctic still has a polar bear. But, with that all being said, could the pizzly allow for bears to continue to exist in intermediate regions of the Arctic? Possibly, yes. That’s why we need to continue to study them.”
