Polar bear cubs are born at about the same time every year, in the last days of December.

“Environmentalists estimate that around 5,000 polar bears are born throughout the world every year,” said Viktor Nikiforov, Head of the Russian WWF’s Polar Bear Patrol project. “Unfortunately, we know little about how many polar bears there are in Russia, as a full count of just one population with icebreakers and helicopters costs several million dollars.”

He also said that polar bears give birth to their young in late December, for which reason the Polar Bear Birthday is celebrated on 29 December. This day was first observed in 2008 and has since become a tradition.