Researchers in the Arctic Basin yesterday spotted a hugely fat pregnant polar bear female on broken ice over water about 2,500 meters deep. Some people seem to find this surprising but it’s what I discussed last week.
Photo above by Tim Kenna from aboard the Coast Guard cutter Healy. Researchers are in the area as part of the “TRACES of Change in the Arctic” program. Another perspective on the bear and the location it was spotted on 24 August 2015 below, as well as some background on Arctic Basin bears.
A polar bear paper just out in Science concludes the experts were wrong, polar bears are not “walking hibernators” – in summer, they slow down and live off their accumulated fat just like other mammals. Take home message: experts are not infallible and spring fat is critical for polar bear survival over the summer.
This paper presents no compelling evidence that Southern Beaufort polar bears, or those in any other region, lack the ability to survive predicted summer sea ice declines in future decades – although they claim it does. See what you think.
Posted in Life History, Sea ice habitat
Tagged Alaska, Amstrup, Arctic Fallacy, Beaufort Sea, Ben-David, fast, fat, hibernation, polar bear science, polar bears, Regehr, sea ice, Southern Beaufort, summer, temperatures, walking hibernator, Whiteman
Some polar bears may already be living mostly off the fat put on over the spring but others may catch a seal or two on the sea ice before the summer fast begins – since the ice hasn’t left the coast in most regions quite yet. Polar bears eat little in summer, whether they spend their time on land or on the sea ice.
Sea ice is still high over Hudson Bay – for this time of year, it hasn’t had this much polar bear habitat since 2009. Davis Strait and Foxe Basin are also above average – Davis Strait hasn’t had this much ice since 1992 (the Mt. Pinatubo cold year). Polar bear subpopulation refresher map below.
Posted in Sea ice habitat
Tagged Alaska, breakup, condition, Davis Strait, fasting, fat, habitat, Hudson Bay, polar bear, science, sea ice, Southern Beaufort, summer, Svalbard
A Southern Beaufort female with cubs, from the fall of 2007.
Note the non-starving condition.
Twenty-one amazing photos of polar bears feasting on the remains of a bowhead whale carcass outside of Kaktovik, Alaska, taken by wildlife photographer Michal Tyl, have been posted by the UK Daily Mail (December 12, 2013): “Now that’s what you call a spare rib! Pack of bloody-faced polar bears spend day and night stripping a beached whale to its bones.” Have a look and see if you can spot any “starving” bears!
What you will see is the relative size of the bears: notice how much larger males are than females, how small cubs-of-the-year are relative to big males. Oh, and notice all the big fat polar bear butts. I can’t include any of the photos here because of copyright rules (the one above is from 2007) but I have included a map showing the location of Kaktovik, a quote from the article, and a link to my previous post on Kaktovik bears, which has a wealth of background information. Continue reading
Spring is the busiest and most important season for polar bears: it is the most important feeding period and it is also when mating occurs. The fat that polar bears put on during the spring and early summer is critical for their survival over the rest of the year and for females, determines whether they can successfully produce cubs the following year.
Mothers and new cubs emerge from their winter dens in late March to early April and those who have chosen to den on land soon head towards the sea ice. For a fabulous photo of a polar bear female and her two young cubs, just out of their winter den, feeding on a bearded seal pup, pop over here. All other bears, including females with older cubs, will already be on the ice, feeding on the first newborn ice seals of the season and any other seals they can catch.
It’s buffet time for polar bears but the most dangerous time for cute baby seals. Continue reading
Posted in Life History, Sea ice habitat
Tagged bearded seals, Bering