It's not pawsible, is it? Brown and polar bears on a hunting trip together? 

Reports recently have revealed mating between grizzly and polar bears in North America, and it is claimed climate change is bringing the two species closer together. 

A similar global warming effect could be happening in Siberia, with brown and polar bears finding love. And it's true that polar bears do very occasionally reach the Kamchatka peninsula in the extreme east of Russia. 

Yet the explanation here seems different. This is a brown bear mother with her two cubs. One is brown and the other pure white. They were spotted by tourists on a rafting trip on the Bustraya River, in the Ust-Bolsherechensk district of Kamchatka.

Senior research fellow at the Kronotsky Nature Reserve Alexander Nikanorov said: 'I have been working in the reserve for more than 40 years and observing the bears. 

'This is the first case of meeting with the bear of such a colour. It's not an albino, of course, because he has a black nose, rather than pink, as it should be if the bear is albino. But it is very white.'

He believes the explanation is a rare mutation. The bear is about three years old, he said. Soon the animal will begin its 'adult life', and it is possible this 'white brown bear' will pass its colour to future generations?

'On Kamchatka we have in the past spotted brown bears of unusual colours - pale fawn, ginger, and light brown.' 

A question for the wildlife experts here is whether the bear will be helped or hindered as it goes it alone. Certainly, as the picture shows, the bears mother had no problems accepting her white cub.