Polar Bear Blog – Sharing Seals

Its a pretty quiet time for the blog and for the bears. Polar bears are not overly keen on polar vortexes either, they mostly sit and wait out blizzards, sit and wait for spring. One researcher, Nikita Osyanikov, observed that polar bears routinely den up, at least in northern Russia. Male polar bears and young bears stay in dens up to 52 days a year, females with yearlings sleep up to 106 days and females without cubs remain dormant as much as 125 days… While I am sure it varies, one thing for certain is that the bears did a whole lot of not very much in January… like most of us.

What did happen in January, was that two pretty interesting news articles came out about polar bears. One was a series of photographs of a mother polar bear and her two cubs aggressively pushing off a male from a seal kill. You can find the polar bear photo series here… really neat stuff.

What is a bit ‘off’ is the commentary. The researcher, Steve Amstrup, and the PBI volunteers commented that this was unusual behaviour and that none of them had ever seen it – understandable since Amstrup is the only person with real bear experience in the groups and research experience unfortunately results in little behavioural observations.

So the mix up is understandable I suppose because females with cubs are often quite dominant animals. Of course, the young mothers, the old bears and the skinny bears very often choose retreat over anything, the prime females really have a way of taking charge, or at least standing up for themselves quite well. We have seen it many times over the years in Churchill.

Families will bunch together when presented with a perceived threat, however, once together they are just as likely to challenge that threat. We have even seen females let their cubs take the lead, feeling that they have caused a big old bear to back down when it was actually mom standing right behind them, head lowered and glaring.

Again, Osyanikov describes it quite well – this was back from the early 1990s – ‘My observations on Wrangel Island revealed that females with cubs were the most aggressive interactions in the polar bear community. Often a female would bite an adult male or strike him with her forepaw during an aggressive charge, but instead of retaliating the male always retreated. Once on Cape Churchill, I observed an irate female with two two year old cubs. She was so determined to push away a huge adult male that had come too close to her family that she attacked him five times in succession.’

‘The fifth time, while striking at him with her forepaw, she lost her balance and fell down onto the snow. Even then the male did not press his advantage, he merely opened his mouth as he tried to fend her off while taking a few steps backward.’

What was interesting was that during the whole confrontation, a sub-adult male (?) kept feeding the whole time. Once the larger male had been pushed back, the family went over and shared the seal with the other bear. Sharing happens a lot with bears, given that the proper etiquette is followed, of course. Neat stuff either way.

Another interesting thing – an omission this time – is that the aerial study that they were on found a large number of bears along the coast in early November. This is the same aerial survey that has been seeing increasing numbers of polar bears over the course of the project, however, this data was not released until 2012, and only as part of a Nunavut funded study. Probably some data that we should take a real hard look at before we ship more bears to zoos.

The second article involves new research from Rocky and Linda. Rocky Rockwell has been heavily involved with the goose research station at Nestor Two for somewhere around forty years. Linda Gormezano has been working on scat analysis and hair sampling from polar bears which unfortunately hit several roadblocks in Churchill. Either way, I totally support this researcher, the more non-invasive information we can gather the better.

So, the study came out this winter and states that bears may be able to compensate for longer periods on land by foraging on grasses and eating goose eggs, caribou, etc. It does also state that the variety in their diet has increased over the years, likely a cause of longer ice free seasons… which, while there is debate about the actual length, most everyone agrees that the bears are on land a longer than they used to be. And, of course, you can’t actually get a polar bear paper published unless you give a nod to climate change

My one difficulty with the articles on this paper is that they make it out as if the polar bears are forced to forage because of a warming climate. In truth, polar bears have always had a varied diet. Yes, their primary focus is seal but they are opportunists and even the early whalers noticed them feeding on grasses and such, even comparing them to sheep grazing in herds. And then they slaughtered them, but that’s a different blog entry.

Anyway, there were many obersvations of summer foraging in the late 1960s near Churchill, as well as the early 1990s and all along. Bears will dive to feed on kelp and algae on the ocean floor. They have always scaled cliffs to raid nests and occasionally attacked walrus. Females emerging from the maternity dens will sometimes graze for a number of days before heading to the seal hunting grounds on the ice. They even make open water seal kills. Its such a shame that all of this creativity is simply lumped into ‘oh look what the poor bears have to do now’.

What else? We figured out that polar bear hair transmits infrared light to the skin to warm it and that the media has overblown the effects of hunting on polar bears in an effort to have them classified as endangered – although I am by no means a fan of hunting. The PBSG is about to re-assess the global population size and one would think that can only be in an upward trend with the increase in the Chukchi Sea population and less than expected decreases in Hudson Bay. We’ll see…

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