Polar bear numbers predicted to plummet

Loss of sea-ice habitat due to climate warming has been highlighted as the single most important threat to the long-term survival of polar bears, and could see the animal’s population decline by more than 30 per cent over the next 35 to 40 years, says the International Union for Conservation of Nature.

The prediction headlined the IUCN’s release of its updated Red List of Threatened Species, which includes 79,837 assessed species, 23,250 of which are threatened with extinction.

“Based on the latest, most robust science, this assessment provides evidence that climate change will continue to seriously threaten polar bear survival in the future,” said Inger Andersen, IUCN director general. “Climate change impacts go far beyond this iconic species, and present a threat our planet has never faced before.”

The IUCN update said that recent studies show that the loss of Arctic sea ice has progressed faster than most climate models had predicted, with September sea ice extent declining at a linear rate of 14 per cent per decade from 1979 through 2011.

“As polar bears rely on sea ice to access their prey, an annual ice-free period of five months or more will cause extended fasting for the species, which is likely to lead to increased reproductive failure and starvation in some areas,” the IUCN update said. “According to recent sea ice projections, large regions of the Canadian Arctic Archipelago will be ice free for more than five months by the late 21st century; and in other parts of the Arctic, the five-month ice-free threshold may be reached by the middle of the 21st centur

New Canadian research confirms polar bears use crosswinds to sniff out their food

It’s an idea that seems as plain as the nose on a polar bear’s face. But researchers at the University of Alberta have proven that the animal uses its sense of smell to track prey, marking the first time that crosswinds have been shown to play a role in how a mammal hunts.

Researchers Ron Togunov and Andrew Derocher recently published the results of an 11-year study that merged polar bear movements with wind patterns on Hudson Bay.

Ringed seals, the bears’ preferred meal, give birth out of sight, hidden under layers of snow. Researchers knew that polar bears used their sense of smell to find the hidden seals, but Togunov says, “how they use that sense of smell had only been theoretical.”

Togunov and Derocher used satellite telemetry for their study, which allowed them to track both the movements of the wind and 123 polar bears simultaneously.

“Predators search for prey using odours in the air, and their success depends on how they move relative to the wind,” explains Togunov. “Traveling crosswind gives the bears a steady supply of new air streams and maximizes the area they can sense through smell.”

Now Togunov is looking at how wind speed affects the way polar bears hunt. As the Earth warms, the speed of Arctic winds is projected to rise and researchers predict this could make it harder for polar bears to find food. “Fast winds are associated with a decrease in foraging,” he says. “They make it more difficult for the bears to find the source of the smell they detect, but I don’t know at which wind speed it’s actually unfavourable.”

“We can’t conclusively say what effect it’s going to have on the bears,” he added, because “we don’t know how big of a role wind is playing. But we can say it’s definitely not going to be good.”