Journalist Kieran Mulvaney says he first fell under the spell of polar bears almost a decade ago, when he went to visit Alaska on assignment. His new book about polar bears is called The Great White Bear (Houghton Mifflin Harcourt, 2011). He told EarthSky:
Polar bears are creatures of paradox. They live in the Arctic, one of the coldest regions on Earth, but their problem isn’t staying warm. They’re so well insulated and adapted to their environment, their problem is staying cool.
He described shafts of a polar bears’ hair as hollow, which allows them to trap warm, insulating air inside each hair. He added that polar bears have black skin underneath their fur, which absorbs heat. Mulvaney said that even polar bears’ mating habits are adapted to their icy environs. He explained that polar bears are free roaming. They’re often thousands of miles apart from one another, on the ice. And yet, he said:
Come springtime, come mating time, males somehow know where the females are. Somehow, they’ll be on a beeline for miles and miles and miles.
Scientists now believe that females leave a scent “impression” on the snow with their paws, he said.
It’s this very, very powerful signal that allows them to find each other over quite vast distances.
Mulvaney said that experts now believe the polar bear population could potentially dwindle from up to 25,000 – what it’s believed to be today – to only a few thousand by the end of the century, mainly owing to the melting of Arctic ice triggered by climate change.
He hopes that everyone who wants to see a polar bear up close gets the chance, while these creatures still “own the ice,” as he put it. He said:
They are extraordinary to watch and spend time around. They are very smart animals. Each polar bear seems to have a different personality. They’re very smart. They’re very patient. It’s very hard not to anthropomorphize polar bears when you watch them in the wild.
The first time we saw a good healthy polar bear off the Russian Arctic, it seemed to be swaggering. Its shoulders were rolling as if it were a prizefighter. And one of the crew on the icebreaker said to me, “Yeeeeeah, look at him. He owns the ice.” They have an air about them that is really unique to these top-of-the-food-chain carnivores.
Add to that a layer of blubber and smaller ears than other bears, so less heat escapes from their heads. He says polar bears are so well insulated, snow doesn’t melt if it lands on them – it just stays put.
He explained how polar bears keep cool, because they’re good at staying so warm:
You often see them resting in the snow, you’ll often see them laying on the ice or punching a hole in the ice so that their butts are in the cold water underneath. They’re capable of great bursts of speed to catch seals, but then after that they have to pant and rest and gather their energy.
He said the first thing he really noticed about polar bears is how quiet they are, and how patient:
I only once ever heard one vocalize in the wild – they have a kind of hiss when they’re frightened. Like a cat. They not only don’t vocalize, but their paws are massive, like snowshoes.
I’ve watched a polar bear pad towards me, and get closer and closer and closer in the snow, and it was only when it was 10 or 12 feet away – I mean, I was safely tucked away overhead – that I heard the very softest of crunches of snow underneath. And of course that’s what makes them good predators.
Another things is they’re very patient. Obviously the Arctic is a difficult environment, and they are prepared to wait a very long time to catch seals. Seemingly for hours to wait for a seal to pop its head through the ice, and then they’ll try and swipe it. And natives, in particular, have said that if they miss the seal after all that time waiting, occasionally they’ll swat the ice in frustration – until they decide to get back down to work and listen again, and wait again.
He said polar bears don’t hibernate, like other species of bears.
In fact, the winter, when most bear species are at hibernating, that’s when polar bear hunting is at its best. But where the ice melts, in Hudson Bay, Canada, for example, during the summer, they have to come ashore. It’s hot, and they’re very hungry, and they rest in dens. It’s not hibernation but it is carnivore lethargy. They do slow down considerably.
He said polar bears are actually referred to as marine mammals, even though, technically, they live on “land.” More truly, they live on top of frozen water. He told EarthSky:
Everything is going on underneath, of course. It’s a tremendously rich marine environment. And at the top of all those animals who are underneath the sea ice are seals, particularly ringed seals. And those are the species that the polar bears absolutely depend on. You’ll hear people say that polar bears need sea ice as a platform for walking, for hunting and for mating.
It’s more than that. Polar bears need sea ice for everything. Without that, they’re not polar bears, they’re not ice bears, because they have evolved to take advantage of the ecosystem that is produced by the sea ice – by the algae that come out of the ice that feed the phytoplankton that feed the zooplankton that feed the fish that feed the seals. Without the sea ice, the Arctic ocean changes completely, and without it, everything that the polar bear has adapted to take advantage of is no longer there.
Listen to the 90-second EarthSky interview with Keiran Mulvaney on why polar bears are cool (at top of page).
Beth Lebwohl researches, writes and helps produce science content in audio and video formats for EarthSky. She is one of the authors on EarthSky.org, a script-writer for our podcasts, and helps host our English science podcasts in 90-second, 8-minute and 22-minute formats. Beth came to EarthSky in 2006 from the American Museum of Natural History's Department of Astrophysics, where she was surrounded by some of the greatest telescope-building, equation-wielding, code-writing physicists of our time. And they made her think . . . this science thing . . . it's pretty cool.