Pizzly or grolar bear

30december2009
Source: bbb.co.uk, photo by Jean-Pierre Lavoie
What do you get when you cross a polar bear with a grizzly bear? A remarkable mix of both bears. This phenomenon was studied at the Osnabruck zoo. Two polar grizzlies were born there.
Only one hybrid of these two bears has ever been spotted in the wild. In 1996 a hunter in Canada shot it. In various zoos across the world there are only a few polar grizzlies. Also in Osnabruck a grizzly bear and a polar bear shared an enclosure. Nothing happened in 24 years, until the female grizzly gave birth to two hybrid cups in 2004. Shortly after their birth the two cubs were moved to another zoo. This way they were not able to learn any behaviours from their parents. The polar grizzlies were studied by zoo staff and scientists from the university of Osnabruck. The cubs show physical characteristics of both parents. Their size is in between that of the larger polar bear and the somewhat smaller grizzly bear. Their neck is just as long as that of the polar bear, but their shoulders resemble more those of the grizzly bear. Their head shape is a mix of both species and also their paws show mixed features. The soles are partly covered in hair. The soles of polar bears are completely covered in hair (for insulation), while the soles of brown bears are completely hairless. The hybrids have visible tails, like polar bears. The tail of the grizzly bear is hardly visible. Also the hybrid’s hair is a remarkable blend. Polar bear hairs are hollow, those of brown bears are not. The hybrids have both types of hairs. In their behaviour the polar grizzlies mostly resemble polar bears. When given large objects to play with (barrels or tractor wheels), they stamp on it with both front legs, just as the polar bear does to break ice. Jute bags are hurled like prey. Brown bears do not show this behaviour.
The male polar grizzly has been sterilized. It is not yet known whether the female polar grizzly is fertile.

The results of this study were published in Der Zoologische Garten.

The photo shows a grizzly bear, by Jean-Pierre Lavoie.
Photo license: Creative Commons Attribution-Share Alike 3.0