It's spring, and bears are in the air.

One my friends lives outside of Anchorage, Alaska and recently had a black bear pay a visit to her backyard. Now her preschoolers are obsessed with bears.

Minnow too has a bit of a bear obsession at the moment, though she hasn't seen any bears in their natural habitat. At school, she's been reading "We're Going on a Bear Hunt" and at home one of her favorite books is the "Berenstain Bear's Big Honey Hunt." Saturday morning, Minnow announced that we were going on a bear hunt, or maybe that we were going to look for bees that would, presumably, lead us to bears. We made it all the way to the end of the block before it started to rain. Disappointed, Minnow and I retreated to the house.

This evening, bears were once again on Minnow's brain. It was still raining, so we had to content ourselves with virtual bears, courtesy of youtube and the BBC. Videos below the fold. But don't worry, I've beefed up the incredible videos with some other tidbits about polar bears and grizzly bears. Enjoy!

Mother polar bear leading a baby polar bear onto the ice for the first time:

Polar bears (Ursus maritimus) spend most of their life out on sea ice, hunting for seals. Typically, the only time they go ashore is to when pregnant females head inland to dig a snow den to give birth. She'll head ashore to an area with snow drifts (sometimes even drifts on ice will do) during the fall. The cubs are born in November or December, and remain with their mom in the den until March or April. At that time, the mom will take them out on the ice for the first time (as shown above). Prior to that, the nursing mother will not have eaten, drunk, or defecated for months in the snow den. Typically two cubs are born at a time, and mothers generally only have five sets of cubs over their lifetimes. (More info here.) Last year, the polar bear was listed by the U.S. as a threatened species, because of Arctic sea ice loss due to global warming. But last week, Secretary of the Interior Ken Salazar announced (echoing the Bush administration) that the Endangered Species Act (ESA) will provide limited protection for polar bears, because the act was never meant to regulate climate change.

Grizzly bears fishing for salmon in an Alaskan river.

Grizzly bears (Usrus arctos), also called brown bears, are the closest relatives of polar bears, and are characterized by a distinct hump on their shoulders. . They are found in Alaska, western Canada, and northwestern parts of the contiguous United States, where they are listed as a threatened species outside of Yellowstone. Grizzlies eat an incredibly diverse omnivorous diet, ranging from dandelions and ants, to moose and salmon. Research in Alberta identified 40 different food items in the stools of grizzlies. Along the Pacific Coast, grizzlies enjoy a seasonal feast when salmon return from the ocean to streams in order to spawn. These salmon make an incredibly arduous upstream swim, and the grizzlies have figured out exactly where the salmon are the most vulnerable (as shown above). Unfortunately, grizzlies that gorge on salmon show elevated levels of persistent organic pollutants relative to their less piscivorous colleagues.