Arctic sea ice at the middle of winter (January-March) is a measure of what’s to come because winter ice is the set-up for early spring, the time when polar bears do most of their feeding on young seals.
[Mid-winter photos of polar bears are hard to come by, partly because the Arctic is still dark for most hours of the day, it’s still bitterly cold, and scientists don’t venture out to do work on polar bears until the end of March at the earliest]
At 12 February this year, the ice was similar in overall extent to 2013 but higher than 2006.
Word that Russia is planning to generate a count of polar bears along its entire Arctic coast within the next few years is good news indeed, as it will resolve a long-standing gap in population estimates that have not been dealt with at all well by the polar bear community. Whether North American and European academics will accept the results of the aerial surveys is another matter entirely, especially if the numbers are higher than they like, which is what happened with the first Russian Kara Sea count in 2013.
Up first will be the Chukchi and East Siberian Seas in 2021, the Laptev and Kara Seas, in 2022, and the eastern Barents Sea around Franz Josef Land in 2023.
Posted in Population
Tagged Barents Sea, Chuckhi Sea, counts, Franz Josef Land, global estimate, IUCN Red List, Kara Sea, Laptev Sea, PBSG, polar bear, population size, Russian
A new paper on Baffin Bay polar bears reports data on body condition and litter sizes collected as part of a major study of the region completed in 2013 compared to sea ice declines since the 1990s; based on a computer model, the authors predict that in 37 years time (if sea ice declines continuously), the incidence of twin litters could “largely disappear.” However, no decline in population numbers was predicted and a critical caveat acknowledges that factors other than changes in sea ice could have affected the body condition and litter size data the authors analyzed, which means the conclusions are scientifically inconclusive.
The last (2013) polar bear population survey of Baffin Bay (SWG 2016) generated an estimate of almost 3,000 (2,826; range 2,059-3,593), which means that regardless of some slight changes in body condition and litter size over the last two decades (which may or may not have been caused by loss of sea ice), there are currently a lot of bears in Baffin Bay.
Posted in Conservation Status, Life History, Sea ice habitat
Tagged baffin bay, body condition, causation, correlation, extinction, fatness, Greenland, litter size, NASA, polar bear, sea ice, weight