Grolar (Grizzly/Polar Bear hybrid) in Osnabruck Zoo (Photo By Corradox – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=63796271)

Dear Readers, there was a very interesting article in New Scientist this week, concerning the hybridisation of polar and grizzly bears. As the Arctic ice that enables polar bears to go north to hunt for seals becomes less and less reliable, polar bears are increasingly moving further south, where their range overlaps with grizzly bears who, finding the climate to their liking, are moving north. Hence, some interbreeding is taking place in the wild. One female polar bear met up with two grizzlies, and had two cubs by each male – three daughters and a son. In a turn of fate that even Shakespeare couldn’t have dreamed up, one of the females then mated with her own father and with the other male that her mother had mated with. She in turn had four cubs.

Scientists were initially excited by this turn of events –  for a start, the cubs of the original mating should have been infertile but, as one of the daughters showed, they could clearly reproduce. Would the offspring be better adapted to the changes occurring due to climate change?

Grolar bears (and pizzlies, bears with a polar bear father and a grizzly bear mother) are more heavily-built than polar bears, with larger feet and heads. Scientists originally conjectured that this might mean that they could hunt for a wider range of prey, rather than being restricted to seals as polar bears are. But, as I learned on my biology course last year, hybrids are often not well-adapted to either of the environments of their parents, being somewhere in the middle between them, and so it proved with these hybrids. There are no wild grolar bears/pizzlies except for the ones that we already know about. These bears don’t have the non-slip paws of polar bears, and so can’t hunt on the ice, but they also don’t have the massive forelimbs and shoulders of grizzly bears, which enable them to hunt terrestrial prey. It seems that they are not the future of bears in the far north after all.

Grolars and pizzlies are not the only climate-induced hybrids that exist as populations that were once separate move together – there are blynxes (bob-cat/lynx hybrids) in North America, and coywolves, the result of wolf/coyote matings. Where both animals serve a similar purpose in an ecosystem, these hybrids might not have much of a knock-on effect on their ecosystems, but where they have different ‘habits’ things could change significantly. For example, grizzly bears leave carrion for other animals to feed on, but polar bears eat pretty much everything. If grolars and pizzlies inherited the polar bear habits, this could have a significant effect on the grizzly ecosystem.

However, this is largely hypothetical. It looks as if grolars and pizzlies are not common, and are unlikely to be the future of Arctic bears. It’s ironic that the word ‘Arctic’ actually means ‘with bears’ (Antarctic meaning ‘no bears’). Our only hope is a) that climate change is actually taken seriously by our governments and something is done about it or b) that polar bears learn to eat some of the prey that grizzlies currently take. Neither is likely, but hope was the last thing left in Pandora’s box, as we know.

Incidentally the bear in the photo was the result of a grizzly/polar bear mating at Osnabruck zoo. Whether this was an accident or a deliberate attempt by the Zoo to raise an ‘unusual’ animal isn’t clear to me. Two hybrid cubs were born, and the female, Tips (in the photo) was shot dead after escaping from her enclosure in 2017. It’s an open question about whether any animals should be in zoos, but clearly this was a desperately unhappy end to an unhappy story. Not very festive, I know. I promise to ease up on the misery going forward.