Canadian Arctic polar bears are swimming longer distances to find suitable ice in which to hunt seals and rear their young. Scientists are deeply concerned that such swims of several days duration, particularly in the Beaufort Sea, are the cause of population decline in the Arctic.
Canadian researchers tracked 58 adult female polar bears as well as 18 young male and female bears between 2007 and 2012 in the Beaufort Sea. Another group of 59 adult females in the Hudson Bay region were tracked as well. Since adult males typically remove their collars and their larger neck size generally makes it difficult to attach the collars, only the females were tracked.
Polar bears are swimming longer distances especially in the Beaufort Sea. Andrew Derocher photo.
Overall, the Hudson Bay polar bears, those including the Churchill population, rarely made long-distance swims.
However, in the Beaufort Sea, during times when sea ice dissipates, many of the polar bears made at least one swim of 50 km or more while 69 per cent did so in 2012, a record low year for ice coverage.
“More and more animals in the population are being caught in places that they just can’t stay – so the ice that they’re on is breaking up, the floes are too small, and they have to make longer distance movements to try to find better habitat,” said Andrew Derocher, a University of Alberta biologist highly involved in the study.
Researchers identified a total of 115 long-distance swims during the study, 100 of them in the Beaufort Sea, with the average distance being 92 km or thew equivalent of 3.4 days. Polar bears average swimming speed is around two km/hour. The bears have very little rest while swimming, rarely stopping and since swimming burns calories at a higher rate than walking, body fat needed for Arctic survival burns away rapidly. One female was tracked on a nine – day, 687 km swim lost her cub on the journey while also dropping 22 per cent of her weight.
Polar bear sow and cub swimming in the Hudson Bay. John Lehmann photo.
The polar bear population in the Beaufort Sea has fallen more than 50 per cent in the past 10 years, according to Derocher. The long – distance swimming could have a huge bearing on this data. “So it is a concern that this is probably one of the factors associated with the population decline,” he said.
However, the study found no direct evidence that swimming contributes to the population decline. The polar bears tracked survived all the swims recorded in the study. Researchers were unable to track survival rates of cubs whom may have been with them other than the one extended swim referred to above. Due to hypothermia exposure to cubs, mothers with young seemed to make fewer marathon swims the researchers noted.
“Polar bears are well adapted to swimming,” Derocher said, “but of course, not all polar bears are created equal when it comes to the ability to swim.” Younger bears do not have the insulating body fat nor the stamina for prolonged water journeys.
Until the 1980’s Sea ice in the Beaufort Sea always melted close to shore as summer arrived. With the ice edge visible from land, polar bears utilize that edge during migration as a way to manage their hunting grounds. As the Arctic warms and the summer sea ice edge extends farther and farther north, polar bears are forced to swim long expanses to find stable ice.
Polar bears will need to find alternate food sources in order to survive. Andrew Derocher photo.
The dynamic Hudson Bay polar bear population has adapted to ice completely melting in summertime by spending long periods of time on land and in the shallows. Reliant on other food sources, polar bears in this region, including Churchill, have adapted somewhat and continue to develop ways to augment their winter food sources. Beluga whales, berries, bird – eggs and land seal – kills are more common food sources these days for the animals.
Polar bear and ravens scavenge a seal kill carcass on land in Churchill Wildlife Management Area. Brad Josephs photo.
Despite Scientists previous predictions that polar bears would need to swim farther as climate change causes chaos with Arctic sea ice, this was the first study showing enough data to actually show the correlation.
Fortunately the “last ice” region we are discussing is being used in a manner of symbolism. The area of interest is above Canada’s High Arctic Islands and northwest Greenland. National Geographic Society and World Wildlife Fund-Canada are on a mission to protect the Arctic.
Since the late 1970s when satellite monitoring was instituted, Arctic summer sea ice extent has been shrinking at a rate of about 12 per cent per decade, according to both organizations in an August news release.
Polar bear on sea ice in the high Arctic. Natural Habitat Photo.
The two organizations have teamed up to increase attention and awareness of — the “Last Ice Area” — the region climate scientists project summer sea ice to last the longest.
Recognizing the ‘Last Ice Area’ and the need to protect it for ice-dependent species and northern communities has been a top priority of our Arctic work for several years,” said WWF-Canada President and CEO David Miller. “We couldn’t have asked for a better partner to help steer the public eye northward to this important region.”
The National Geographic Pristine Seas project will include partner WWF-Canada to bring attention to the threats facing the summer sea ice and document “how the Inuit culture is connected to the area and its extraordinary wildlife.”
The “last ice area” near Greenland. Jane George photo.
“Highlighting the ‘Last Ice Area’ and the need to protect it for ice-dependent species and northern communities has been a top priority of our Arctic work for several years,” said WWF-Canada President and CEO David Miller. “We couldn’t have asked for a better partner to help steer the public eye northward to this important region.”
The Pristine Seas project by National Geographic will partner with WWF-Canada to spread awareness of the threats of shrinking summer sea ice areas. The connection between the inuit culture of the north and the extraordinary wildlife will be the primary focus.
“We came close to Arctic wildlife and filmed them like never before while also documenting the last traditional hunting by the Inuit,” said National Geographic’s Enric Sala about a recent trip to northern Baffin Island.
Polar bear on sea ice in the Arctic. Nasa photo.
The Arctic summer of 2013 was a cool one. So much so that the trend of decreasing sea ice has regained it’s recent losses by at least one third over the last few years. Because of the cool summer that year, more multi – year ice was left at the end of the summer.
Despite the encouraging news, scientists cautiously warn the news is an anomaly and climate change related to warming is still very real.
“It would suggest that sea is more resilient perhaps if you get one year of cooler temperature. We’ve almost wound the clock back a few years on this gradual decline that’s been happening over decades,” lead author Rachel Tilling told BBC News. “The long-term trend of the ice volume is downwards and the long-term trend of the temperatures in the Arctic is upwards and this finding doesn’t give us any reason to disbelieve that. As far as we can tell, it’s just one anomalous year.”
President Obama will visit Anchorage, Alaska on August 31 to address the state departments GLACIER conference. Foreign ministers from Arctic nations as well as non – Arctic states will attend as well as scientists, policy makers and stakeholders from the Arctic and Alaska will also attend.
The conference goal is to increase global awareness of how Arctic climate change is a harbinger for warming affects in the rest of the world.