Polar bears in Canada’s western Hudson Bay are beginning to come ashore for the summer, four weeks earlier than the average return date during the 1980s. Because the ice in Hudson Bay melts completely during summer, the region’s polar bears – which, like all members of the species, hunt seals on sea ice – spend the summer months holed up in cool earthen dens until the ice returns.
Because sea ice has been melting earlier and forming later in the bay in recent years, bears have been forced to spend more time on land and less on the ice, reducing their ability to eat and raising concerns about the population’s future.
According to the National Snow and Ice Data Center, Arctic sea ice extent in June was at a record low for the month, with Hudson Bay among the areas where ice retreat was most pronounced.
Farther east, scientists from the Norwegian Polar Institute (NPI) found that the number of dens on Kongsøya, an important denning area in Norway’s Svalbard islands, has fallen sharply in the past few years.
Pregnant polar bears carve dens into snowdrifts, where they give birth; WWF reports that three years ago, when winter sea ice around the island formed in mid-October, scientists from NPI found 25 dens, but this most recent winter, with sea ice forming only in December, they found just five. The late ice formation likely makes it difficult for many bears to reach the islands in time to make dens and have the cubs grow large enough by spring. The researchers say they don’t know if bears are simply going elsewhere or waiting another year to give birth.
On a lighter note, here is video of Russian polar bear patrol officer and researcher Vladilen Kavriy singing two polar bears to sleep with a lullaby. We do not encourage trying this at home.
Photograph: A polar bear cools himself on early winter ice on the shores of Hudson Bay. Photo by Kieran Mulvaney