Siku the Polar Bear and the Power of Biophilia

Since my last polar bear post, about intraspecies cannibalism, was a little graphic I wanted to share a cute polar bear video that has recently been tearing up the internet. Siku is a polar bear cub who was abandoned by his mother. The cub was born on November 22, 2011 and is currently being cared for at Denmark's Scandinavian Wildlife Park. I just want to rub his belly. I justify putting up a cute polar bear video with the fact that biophilia, Edward O. Wilson's idea that human love of animals is rooted in our biology, explains why the cuteness so easily creates an internet sensation.

Biophilia is an interesting concept that I first learned about when reading Hal Herzog's book Some We Love, Some We Hate, Some We Eat for Patricia McConnell's human and animal behavior class in Spring 2010. Biophilia can be applied to animals, but goes further into human attachment to all things natural, including whole environments. For more information you can check out Wilson's original 1984 book. Or, just enjoy the polar bear video, which I think will pretty much explain how biophilia works.

Polar Bears Resort To Cannibalism

If a picture is worth a thousand words, for me this one is worth a thousand nightmares:

Photograph by Jenny Ross.

The photograph was captured by Jenny Ross, an environmental photojournalist working in Olgastretet, a part of the Svalbard archipelago, located in the Arctic north of Norway. Ross co-authored a paper with Dr. Ian Sterling a biologist with Environment Canada and a professor at the University of Alberta, about the photographs and observed instances of cannibalism among polar bears. 

For anyone who reads Science Decoded regularly, I don't have to tell you that polar bears are sort of my thing. I've written about them being Irish, mysteriously dying, having osteoarthritis, status as endangered, and their habitat needs. I make no bones about the fact that they are my favorite and I love them. I've loved them since I was a little kid, and have a large collection of polar bear themed...stuff. From earrings to ice cream scoops, I've got it all. My collection doesn't include nightmare inducing, zombie-evoking images of polar bears eating each other. The child in me is horrified by what I now know to be a normal occurrence.

Yes, that's right. While the above photograph might be some of the most jarring evidence to date about intraspecies polar bear predation, the behavior isn't abnormal. In fact, according to Dr. Stirling instances of infanticide (killing baby bears) and predation on older bears, in addition to cannibalism have been known to Inuit hunters in Canada and Greenland and reported in scientific literature. In these instances, the bear doing the killing is always an adult male, which would have the advantage over young bears, old bears, and even adult females.

In the paper with Ross, Stirling reports on three instances of what is most likely intraspecific killing and subsequent cannibalism by adult male polar bears. The instances were all observed on the sea ice in Svalbard in midsummer and early autumn. Each incident was photographed (see above). The victims in each case were killed by more than one bite to the head. This is an instantly lethal way to take down prey, and the way that polar bears would take down seals, their typical food source.

According to Stirling, the instances of cannibalism described in the paper, published in the journal Arctic, are different than the normal instances of intraspecies predation. The bears that did the killing appeared to be in good physical condition, not obviously thin which is typically the case in intraspecies killings. Stirling and Ross concluded that the behavioral and ecological factors present in the instances of killing they describe in their paper show that by late summer, when available ice and the number of seals to hunt are significantly reduced, young polar bears may become a source of prey for adult males to still hunt from the surface of the remaining sea ice. While this type of behavior may be relatively normal, Stirling says that as climate continues to warm and reduce sea ice the frequency of kills like this may increase.

I asked Stirling what we should take away from these photographs, and the instances of polar bear cannibalism, and this is what he said:

"Climate-driven concerns for polar bears are real. The bottom line is that polar bears need ice to hunt from and without that, most bears will not be able to survive. At present, it looks like the last ice will be in the area of the northern Canadian Arctic and in Greenland. Some relatively small, but unknown, number of bears may survive there for some time after they cannot continue in more southerly areas."

So basically, cannibalism is a natural behavior for polar bears. It happens. But due to climate change and the changes that are occurring to sea ice, it is likely that cannibalism is going to get worse. Which leads me to think, do we really want a unique and charismatic species that many people are working to protect to be eating itself? It seems somewhat backwards to invest in conservation and then just watch the bears duke it out amongst themselves. I wish there was a solution I could offer but climate change is its own beast entirely. I will say that intraspecies cannibalism wasn't something I had on my mind when thinking about conservation, but I'll definitely remember it next time.

Polar Bears Have The Luck Of The Irish

I recently learned that I share a trait with my absolute favorite animal, the polar bear, in that we can both trace our ancestry back to Ireland. For people who follow this blog, or have at least looked back through the archives a bit, you'll see that I find it impossible to pass up a good polar bear story. I've written about animal healthcare, mysterious death, and the polar bear's status (or lack thereof) as an endangered species. So it should come as no surprise that I can't pass up the opportunity to talk about this new research that shows an ancient Irish connection to modern day polar bears.

via Wikimedia Commons

A team of researchers led by Beth Shapiro of Penn State University and Daniel Bradley of Trinity College (Dublin) has identified a common ancestor of polar bears (Ursus maritimus) and brown bears  (Ursus arctos) that lived in Ireland before the peak of the last ice age some 20,000 to 50,000 years ago. The researchers concluded that all modern day polar bears can trace their lineage back to this ancient female brown bear. The specific lineage of the brown bear that shared their mitochondrial DNA with polar bears went extinct around 9,000 years ago, but the research still shows that the modern species are related.

Despite significant differences between polar bears and brown bears (size, coloring, fur type, tooth shape, swimming ability vs. climbing ability, etc.) scientists have suspected for some time that the species have closely connected histories. The polar bear is known to have mitochondrial DNA (the part of the genome contributed by the mother) that traces back to the brown bear. But how modern polar bears acquired this brown bear DNA was a bit of a mystery.

via Wikimedia Commons

The two species are known to interbreed, and have been studied in captivity in addition to being spotted in the wild. An example of a polar bear/brown bear hybrid, jokingly nicknamed grolar bear or pizzly, was found in the wild Canada in 2006. But, even with the knowledge that the two species can co-mingle scientists were still perplexed about the history of these different species. The long standing theory about how polar bears evolved from brown bears had their history traced to the ABC Islands (the Alaskan Islands of Admiralty, Baranof, and Chichagof) around 14,000 years ago. But the bears' genomes tell us a different story.

The research team led by Shapiro and Bradley found that the hybridization of polar bears occurred much earlier than would have been possible on the ABC Islands through a genetic analysis of the bears. The study analyzed 242 samples from polar bear and brown bear mitochondrial DNA spanning 120,000 years and several different geographical regions. The researchers found that the fixation of the mitochondrial genome in polar bears likely occurred closer to 50,000 years ago in the area of present-day Ireland.

According to Shapiro, in addition to genetic evidence, the interconnected history of the polar bear and brown bear is also supported by climate events. One example of this is the British-Irish ice sheet, which reached its maximum range around 20,000 years ago. At this time parts of Ireland would have been difficult to inhabit, pushing bears from the warmer areas toward ice shelves and land exposed by lower sea levels. This would have brought the bears into close contact with their northern neighbors, showing how the animals that became two different bear species could have started out in the similar location, sharing their genes.

The polar bear is currently considered a threatened species, and future conservation efforts may be aided by this new understanding of its genetic history and its ability to hybridize with the brown bear. The research is described in the paper, "Ancient Hybridization and an Irish Origin for the Modern Polar Bear Matriline" in the journal Current Biology.

Knut the Polar Bear Dead At Age Four

Knut as a baby. Source: Wikimedia Commons

Yes, I am posting a memorial piece for a polar bear. Yes, I know that I talk about polar bears too much. But, this really is an interesting case of mysterious death - one that was witnessed by hundreds and has cause an onslaught of media coverage of what may very well be history's most widely read polar bear obituary.

Knut was a polar bear born in captivity in the Berlin Zoo in December of 2006. He gained world wide fame, basically for being so darn cute. He was raised by the zookeepers after being rejected by his mother and was the first polar bear to survive infancy at the Berlin Zoo in 30 years. He died March 19, 2011 in his enclosure at the zoo in front of an estimated 700 viewers. His death has been the subject of worldwide media coverage from the UK's Daily Mail to New York Magazine.

Reports say that the polar bear had a spasm, and was then seen floating in the water in the enclosure before the exhibit was closed off by zoo personnel. Polar bears in captivity have been known to live up to 30 years, and Knut was not known to have any medical problems so his sudden death at age four is mysterious. A necropsy (an autopsy for animals) will be performed to determine what happened to the bear.

Knut a little older. Source: Wikimedia Commons

As far as polar bears go, you couldn't have a bigger celebrity than Knut. He was on the cover of Vanity Fair in 2007, he has been marketed through plush toys and children's books, he was the subject documentary films and even had his name trademarked by the Berlin Zoo. His untimely death even warranted him an obituary in People Magazine's website.

While I don't intend to get sappy about the loss of this animal, I do think it is important to note because Knut succeeded in getting people to feel emotionally invested in animal rights issues and to get people talking about science topics like climate change (and its effects on polar bears). He was a major draw to the Berlin Zoo and the loss of revenue will most certainly be felt. Hopefully the necropsy will be able to determine how he died so that zookeepers can learn something about how to keep animals in captivity healthy.

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Update 4/1/11 - The Berlin Zoo has released the results of Knut's necropsy. The findings show that the polar bear's official cause of death is drowning, which occurred when he collapsed into the pool in his enclosure. The reason Knut collapsed is still a bit of a mystery. The necropsy showed encephalitis (brain swelling and irritation) most likely caused by a virus, although the exact virus remains to be identified. So far rabies, botulism, and bovine spongiform encephalopathy (mad cow disease) have been definitively ruled out as the cause of the brain swelling. The zoo will continue to test Knut's remains to try to identify the virus.