polarbearscience

Polar bears are leanest – and therefore, hungriest – at the end of March, not in the summer, as chemist Crispin Halsall stated in a recent article about working in the Arctic.

Recent September 1st stories by CNN and the BBC, based on a press release by WWF Russia on 27 August 2015, that five bears in the southern Kara Sea were hanging around a weather station and frightening workers there, apparently prompted chemist Crispen Halsall to make a nonsensical statement about polar bears being at their “hungriest” in summer (first here, reproduced here and picked up yesterday (September 5) by The Guardian here).

“In the path of the polar bears: what it’s like to be an Arctic scientist” (4 September 2015; Crispin Halsall, Reader in Environmental Chemistry at Lancaster University) had this to say:

“The case of Russian scientists trapped in their remote Arctic base by a group of inquisitive yet hungry polar bears does not come as a surprise. By late summer, Arctic sea ice is at a minimum and polar bears are effectively landlocked in coastal areas eagerly awaiting the return of ice during the autumn freeze and the chance to hunt seals again.

The Arctic summer is also the time of year when scientific activities are at their maximum, with bases operating at capacity and fieldwork operations at full flow, particularly in tundra and coastal regions. Polar bears are hungriest when scientists are busiest – “encounters” are inevitable.” [my bold]

Polar bears are leanest – and therefore, the hungriest – at the end of winter (when it is more likely to kill with the intent to consume human prey) as stated clearly by Stirling and Øritsland (1995:2603):

“Polar bears reach their lightest weights for the year in late March, just prior to the birth of the next cohort of ringed seal pups, which also suggests that it is the success of their hunting in spring and early summer that gives them the body reserves they need to survive through the rest of the year.” [my bold]

A polar bear that has not fed properly in spring – because it was young and inexperienced, too old or too young to defend its kills from bigger, stronger bears, or simply sick or injured – it might be unusually hungry in summer but it’s not the norm.  Polar bears eat nothing or very little over the summer (whether on land or on the ice) because they live off their stored fat – the physiological condition known as ‘fasting.’

The photos and video in the September 1, 2015 BBC story of the Russian bears shows this: the bears are fat, not skinny (“Video caption: Five bears settled near the weather station on the north Russian island of Vaygach, as Frankie McCamley reports”):

Polar bears might approach humans working in the Arctic during the summer because they are curious and/or bored, and they might attack and even eat humans because they have a drive to eat whenever the opportunity arises. But it’s not because they are “hungriest” in the summer.

References
Stirling, I. and Øritsland, N. A. 1995. Relationships between estimates of ringed seal (Phoca hispida) and polar bear (Ursus maritimus) populations in the Canadian Arctic. Canadian Journal of Fisheries and Aquatic Sciences 52: 2594 – 2612. http://www.nrcresearchpress.com/doi/abs/10.1139/f95-849#.VNep0y5v_gU