Let Sleeping Bears Lie

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A black bear, which has been sedated, and her cub in a den in Massachusetts. Credit Mark Wilson/The Boston Globe, via Getty Images

Thanks to the science writer Steph Yin for this one:

Waking From Hibernation, the Hard Work of Spring Begins

For animals that hibernate, making it to spring is no small feat. Torpor — the state of reduced bodily activity that occurs during hibernation — is not restful. By the time they emerge, hibernating animals are often sleep-deprived:Most expend huge bursts of energy to arouse themselves occasionally in the winter so their body temperatures don’t dip too low. This back-and-forth is exhausting, and hibernators do it with little to no food and water. By winter’s end, some have shed more than half their body weight.

But just because it’s spring doesn’t mean it’s time to celebrate. Spring means getting ready for the full speed of summer — and after spending a season in slow motion, that requires some ramping up. Here’s a look at what different animals have on the agenda after coming out of winter’s slumber.

A long wake-up for bears

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A black bear with a salmon in Alaska. A bear would take some time to build up to a meal this large after hibernation, initially noshing on insects and plants instead. Credit Wolfgang Kaehler/LightRocket, via Getty Images

Black bears emerge from their dens in April, but stay lethargic for weeks. During this so-called walking hibernation, they sleep plenty and don’t roam very far. Though they have lost up to one-third of their body weight over winter, they don’t have a huge appetite right away — their metabolism is not yet back to normal. They snack mostly on pussy willows and bunches of snow fleas.

In January or February, some females give birth, typically to two or three cubs. New mothers continue to hibernate, but they go in and out of torpor, staying alert enough to respond to their cubs’ cries. When they emerge from their dens, mama bears find trees with rough bark that her cubs can easily climb for safety.

“Slowly, the bears’ metabolism gears up to normal, active levels,” said Lynn Rogers, a bear expert and principal biologist at the Wildlife Research Institute, a nonprofit in Minnesota. “When plants start sprouting on the forest floor, that’s when they start really moving around.”…

 Read the whole story here.

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