Up to 5,000 polar bear cubs were born in the Arctic in late December on the birthday of polar bears. This special day was celebrated in Russia on December 29 2012 for the fifth time. The day was announced in 2008 by the Council for Marine Mammals public scientific organisation and the WWF Russia.

"If we agree with specialists from the International Union for the Conservation of Nature that the global polar bear population is 20,000-25,000, nearly 4,500-5,000 bear cubs are born during these days all over the world," head of the Bear Patrol project Viktor Nikiforov said. He added that the accuracy of the estimate directly depends on the depth of the research carried out on the 19 sub-populations.

"The sub-populations of the polar bear in the Russian Arctic have undergone the least research. Our observation of the polar bears as part of the Bear Patrol project allows us to monitor the bears on the coast, but protecting and monitoring the animals requires a full blown research programme, with counting first and foremost. The latest polar bear count in the Barents Sea was carried out together with Norway in 2004. Polar bears inhabiting other seas in the Russian Arctic have never been recorded," Nikiforov added.

Tiny bears weighing 500-600 grammes are born in warm dens all over the Arctic. They later grow into white giants, the planet's largest land predators, whose weight may reach 750 kg scientists and wildlife campaigners note.