Hibernating Bears Keep Weirdly Warm

"Amazing" adaptation allows bears to stay fit during winter.

The North American mammals generally slumber about five to seven months without eating, drinking, urinating, or defecating, and then emerge from their dens in the spring none the worse for wear.

Scientists have long known that to survive this lengthy fast, the bears drop their metabolism, the chemical process that converts food to energy.

But it was thought that, like most animals, the bears would have to drop their body temperatures to put the brakes on metabolism—each 18-degree Fahrenheit (10-degree Celsius) drop in temperature should equal a 50-percent reduction in the chemical activity.

Not so, according to the new study. A black bear in Alaska can lower its temperature—generally about 91 degrees Fahrenheit (33 degrees Celsius)—by only about

DON'T MISS THE REST OF THIS STORY!
Create a free account to continue and get unlimited access to hundreds of Nat Geo articles, plus newsletters.

Create your free account to continue reading

No credit card required. Unlimited access to free content.
Or get a Premium Subscription to access the best of Nat Geo - just $19
SUBSCRIBE

Read This Next

Did this mysterious human relative bury its dead?
This new birth control for cats doesn't require surgery
How the Zoot Suit Riots changed America

Go Further

Subscriber Exclusive Content

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet

Why are people so dang obsessed with Mars?

How viruses shape our world

The era of greyhound racing in the U.S. is coming to an end

See how people have imagined life on Mars through history

See how NASA’s new Mars rover will explore the red planet