Rapid reduction of sea ice level due to climate change is hitting the population as hunting ground recedes

The proportion of polar bear females around the Arctic islands of Svalbard who gave birth to cubs crashed to just 10 per cent in 2014, according to a small scientific survey of the animals.

The Barents Sea population of a few thousand polar bears is one of the biggest in the world. But global warming is rapidly reducing the extent of sea ice on which the bears hunt seals, their main food.

The annual survey undertaken by Jon Aars and his colleagues at the Norwegian Polar Institute was conducted in April, just after cubs and mothers leave their dens. They discovered that just three of the 29 adult females they tracked and examined had a cub born that year.

“This is a lower number than we would have expected,” he said. “Typically one third or more of the adult females have cubs from that year.” But even this higher level is in long-term decline: annual records dating back two decades show that about half of adult females in Svalbard had cubs in the mid-1990s.

Like a number of polar populations in remote regions, scientists do not have enough data to say whether Barents Sea polar bear numbers are rising or falling. Aars is confident that numbers bounced back after mass killing of polar bears by hunters was outlawed on Svalbard in 1973, and lie somewhere between 1900 and 3600.

“They were nearly hunted to extinction,” he said. “But we are pretty sure there are more bears now than in 1973, probably about twice as many.” As to the future, he said: “With worse and worse sea ice conditions we think there will come a point when the population will suffer, but we don’t know when that point is.” Winter ice cover in the Arctic fell to its fifth lowest extent on record in 2014. This continues a long-term trend of decline which is occurring more rapidly than scientists expected and the ice cap could vanish in summer within decades. — © Guardian Newspapers Limited, 2014

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