A pizzly bear is a hybrid between a polar bear and a grizzly bear. These hybrids are real, and several have been found in the wild. But the idea that pizzlies are suddenly spreading across the Arctic isn’t supported by the genetic evidence.
A 2017 study found that the eight known wild hybrids in Canada’s western Arctic all came from a single female polar bear that mated with two male grizzlies. And in 2024, researchers analysed samples from more than 800 polar and grizzly bears and found no new hybrids at all. Climate change may give the two species more chances to meet, but there’s no evidence of a pizzly population boom.
What is a pizzly bear?
Polar bears (Ursus maritimus) and grizzly bears (Ursus arctos) are different species, but they’re closely related enough to produce hybrid offspring, and those offspring are fertile. Polar bears evolved from grizzly-like ancestors only several hundred thousand years ago. The hybrids go by several names, including pizzly bear, grolar bear and polar-grizzly hybrid, as Wikipedia’s article on the hybrid explains.
There’s a technical difference between the two most common names, though. A hybrid with a grizzly father and a polar bear mother is a grolar bear, while one with a polar bear father and a grizzly mother is a pizzly. That creates an amusing problem with the famous Canadian hybrids, because all eight had the same polar bear as their mother or grandmother, and grizzly fathers. Strictly speaking, all eight were grolar bears, even though “pizzly” is the name that stuck.
What does a pizzly look like, and how big is it?
There’s no single look that every hybrid must have. They can show a mix of features from both parents, such as pale fur like a polar bear combined with a grizzly’s shoulder hump, long claws or dished face. Many look like a whitish or blonde grizzly with patches of brown. But looks alone can’t prove a bear is a hybrid, and DNA testing is far more reliable.
Size is one of those questions where a confident internet answer can mislead you. Polar bears are generally bigger than grizzlies, and a hybrid can inherit a mix of traits from both. But so few wild hybrids have been documented, and the known ones span different generations, that there’s no reliable average. The safest answer is that a wild pizzly or grolar is a large bear with an appearance somewhere between its parents.
The strange bear found in 2006
The modern pizzly story took off in 2006, when a hunter on Banks Island in Canada’s Northwest Territories shot a bear he thought was a polar bear. It had mostly pale fur, but also brown patches and features that didn’t fit a typical polar bear. DNA testing confirmed it was a polar-grizzly hybrid, the first documented in the wild. That raised an obvious question: was this the start of a new population of hybrid bears?
Eight hybrids, one unusual family
In 2017, biologist Jodie Pongracz and colleagues published a detailed genetic analysis of the known Canadian hybrids in the journal Arctic. They identified eight hybrid bears, but those eight weren’t the result of eight separate matings. All of them traced back to one female polar bear who had mated with two male grizzlies.
She produced four first-generation hybrids, and one of her hybrid daughters then bred with grizzlies to produce four more, each roughly three-quarters grizzly. What had looked like a sudden rise in hybridisation was really one family. Researchers came to describe the mother, who was born in 1989, as a “pretty strange” bear, as CBC News reported.
The 2024 DNA study put the numbers in perspective
The strongest evidence against a pizzly boom came in 2024. A team including Ruth Rivkin of the University of Manitoba developed a genetic chip to look for hidden hybrids: bears that might look like ordinary polar bears or grizzlies but carry the other species’ DNA.
According to Polar Bears International, they tested 371 polar bear and 440 grizzly bear samples from across Canada, Alaska and Greenland, and confirmed that only the eight already-known bears were hybrids. Rivkin said the team was surprised to find no new cases despite speculation that numbers were increasing.
There’s an important caveat, though. As Discover Wildlife notes, the samples were collected between 1975 and 2015, so the study shows hybridisation was extremely rare over those decades, not what’s happening right now. It also wasn’t a census of every bear. But it’s a very different picture from pizzlies spreading across the north.
Does climate change cause pizzly bears?
This is where the story needs nuance rather than dismissal. Climate change can shift where animals live and how often different species meet. Grizzlies have been expanding northward into polar bear country, and changes in sea ice affect how much time polar bears spend on land. More overlap means more chances for the two species to meet, and Rivkin told CBC she expects hybridisation to happen more often in the future.
But more opportunity isn’t the same as frequent hybridisation, and timing explains why. Rivkin has explained that the two species mostly overlap in summer, when polar bears are on the mainland coast waiting for the sea ice to return. Polar bears mate in winter, out on the sea ice, where female grizzlies rarely go. The most accurate summary is that climate change may increase the opportunity for hybridisation, but the evidence doesn’t show wild hybrid numbers rising.
Would hybrids thrive, and are they a new species?
Even if more hybrids were born, there’s no evidence they’d replace polar bears. Polar bears are specialised for life on the sea ice, hunting seals, while grizzlies are adapted to life on land, and a hybrid inherits a mixture of both. Polar Bears International’s Geoff York has said the 2024 study shows hybridisation isn’t an adaptive capability of polar bears, so it’s no solution to the problems they face. For a species the IUCN lists as vulnerable, the far bigger threat from a warming Arctic is losing the sea ice it relies on, not interbreeding.
Pizzlies aren’t a new species either. They’re individuals produced by two different species mating. Some can breed, as the later-generation bears in the Canadian family show, but a new species would need persistent separation from the parent populations over many generations, and there’s no sign of that.
The pizzly is real, the pizzly boom is not
The pizzly is almost designed for a headline: a bear that’s part polar bear and part grizzly, created by a warming Arctic. The reality is more interesting precisely because it’s less dramatic. The eight known wild hybrids turned out to be one extended family, and the 2024 genetic survey of more than 800 bears found no others.
That doesn’t make the animals any less fascinating; it just makes the story more precise. It’s a good reminder to check whether a dramatic trend is really a trend or one unusual case. For another popular science story that needed updating, see Zealandia, the lost continent hidden under the Pacific, and for the terms behind another commonly confused climate topic, see climate change versus global warming.
Sources
Discover Wildlife: Grizzly-polar bear hybrids extremely rare but predicted to rise (2024)
Wikipedia: Grizzly-polar bear hybrid
CBC News: Grolar bear hybrids quite rare, new study finds (2024)