On 29 December, Russia celebrates a special occasion – the birthday of polar bears. At about this time, mother bears give birth to one to three small cubs (less than a kilo) in snowy dens.

“In three months, when the days become longer and the Arctic sun begins to shine brighter, stronger cubs weighing almost 10 kg (all weight gained from their mum’s high-fat milk) will come out of the den with their mother,” says Viktor Nikiforov, the coordinator of environmental projects at the Marine Mammals research and expedition centre.

Cubs can stay with their mother until they are 2.5 years old. The most difficult period is the first year of life. During this time, about 30-50 percent of the cubs die in the severe Arctic conditions.

The polar bear is listed in Russia’s Red Data Book. All polar bear hunting is prohibited in Russia.