Photo of the Day #25: Polar Bear


Polar Bears (Ursus maritimus) have always been favorite animals at zoos and aquariums, but the current problem of anthropogenic global climate change has popularized them further by making them extinction's poster species. While many documentaries show the loss of ice as one of the primary factors that is threatening the bears, the overall rise in temperatures is having a more subtle (but widespread) impact on the unevenly distributed populations of bears. Polar bears have adapted to cold climate so effectively that they do not do well when temperatures exceeding 50 degrees Fahrenheit, and if you see these animals at zoos during the summer you'll notice how affected they are but the hot temperatures. In the wild the bears do not have access to cold pools or rocks year round, however, and the body condition of the bears in many populations has deteriorated due to the effects of warming, the Western Hudson Bay population dropping by about 22% between 1987 and 2004. If you would like to know more about the status of the various polar bear populations, more information can be found through the IUCN Polar Bear Specialist Group.

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I had heard that another factor pressurizing polar bears is that as the Arctic warms, competion species, especially the grizzly bear, migrate further north. Not sure if any truth to that though.

I remember seeing a documentary about polar environments where a male polar bear was searching for food and there were no ice floes...he just ended up drowning. It was horrific and depressing.

Well, there is a possibility that as brown bears move further north, they might compete with polar bears that find themselves being restricted to land; that, and in time to come polar bears could end up hybridising with brown bears.

Amanda: Planet Earth, I presume? According to the show, after some time spent swimming, that particular male polar bear found a walrus colony and unsuccessfully tried to make a kill. He died of his injuries though.

Oh, and this isn't exactly related to polar bears in the wild, but it does raise some of the issues of polar bears in captivity:

That being said, I wonder how Knut is now?

(disclaimer this rant is not directed at you, Brian, just at the situation of our wildlife in general)
I am not one of those people that thinks zoos are universally unfair and evil, but there are a couple of species that I think are very unethical to keep in captivity, and the polar bear is one of them. They are so incredibly active and wide-ranging in the wild, no matter how much money/space you have it's impossible to provide that much physical and mental stimulation in a captive environment. I know, I know, soon there may not be any "wild" left so we need to preserve them, but to me an animal is defined just as much by its ecology as by its body, and a bunch of captive bear bodies with no habitat does not succeed in "saving" the species. I don't mean I think we shouldn't try to save some individuals if in situ conservation fails to be an option . . . but I don't think it should be considered a substitute for protecting habitat.

*steps down off of soapbox*

Fantastic picture, by the way, these are the closest thing we have to the extinct megafauna that used to live in North America, very awe-inspiring.

Dave; Inter-species competition is an issue, but I think the break up of sea-ice and the effect of rising temperatures on the physiology of the bears is going to have a bigger impact. Then again, maybe there will be some polar bears that are more heat-tolerant and will find a niche somewhere, but I think the change is happening much too fast for that to be likely. There have been some polar/grizzly hybrids known in the past, but I don't think such rarities are going to be the rule (i.e. polar bears aren't going to be "absorbed" by populations of grizzlies through reproduction). What's worrisome about the polar bears is that there are so many different pressures affecting them as a result of change, ranging from competition for resources to the breakup of ice to the effects of the temperatures on their bodies; with so much pressure accumulating so fast variations currently existing within the species might not be enough to stave off extinction.

Amanda; I think that was in Planet Earth, although a similar scene was in Arctic Tale, I'm told. Seals are being affected by the loss of ice, as well, many of them are dispersing in order to try and find new beaches to haul out on to give birth (people are finding many drowned pups as the females have nowhere to give birth and suckle their young and do so at sea).

I agree completely, Anne-Marie; the only time I see Polar Bears "happy" is during the winter, the humid east-coast summers being too much for them. It really is a shame, although reintroducing animals that have been at zoos for so long isn't necessarily feasible, so it's a bit of a catch-22. Still, I get aggravated that so many animals are bred at zoos but so few zoos have plans to reintroduce the animals into the wild. Yes, we're no longer taking animals from the wild, but there are so many animals (big carnivores especially) that are living alone in small enclosures, wasting away. That's why I get so sad when I see the male Amur Leopard at the Philadelphia Zoo; his species is disappearing and he's just wasting away in a cage. When we only have tigers, polar bears, orangutans, etc. in zoos and not in the wild, we have truly lost those species no matter what we do from that point on.

Indeed, as much as I like visiting zoos to see these animals they often seem to be a sort of "devil's bargain"; they can be inspirational and get people interested in animals, but few do much to help the wild populations (the WCS is a notable exception). My visits to zoos are often bittersweet for this reason, as I love seeing the animals but I know they're only shadows of what they are in the wild, often growing bored and restless even in the best of circumstances. Don't even get me started on cetaceans in captivity...