Northern Canadian hunters, scientists and people with vivid imaginations have discussed the possibility for years.

In this undated photo provided by the Canadian Wildlife Service, hunter Jim Martell, left, is seen with a hybrid bear he shot while on a hunting expedition on Banks Island, Northwest Territory, Canada. According to Dr. Ian Stirling, researcher for the CWS, genetic tests showed the bear had a polar bear for a mother and a grizzly bear for a father. Roger Kuptana, center, right, was the guide on the expedition. The other men are unidentified. [AP Photo]

But Roger Kuptana, an Inuvialuit guide from Sachs Harbour, North West Territories, was the first to suspect it had actually happened when he proposed that a strange-looking bear shot last month by an American sports hunter might be half polar bear, half grizzly.

Territorial officials seized the creature after noticing its white fur was scattered with brown patches and that it had the long claws and humped back of a grizzly. Now a DNA test has confirmed that it is indeed a hybrid ¡ª possibly the first documented in the wild.

"We've known it's possible, but actually most of us never thought it would happen," said Ian Stirling, a polar bear biologist with the Canadian Wildlife Service in Edmonton.

Polar bears and grizzlies have been successfully paired in zoos before - Stirling could not speculate why - and their offspring are fertile.

Breeding seasons for the two species overlap, though polar bear gets started slightly earlier.