Grizzlies have great sniffers

Hungry Horse News

When it comes to grizzly bears, the nose knows - boy does it know.

Dr. George Stevenson, a retired neurosurgeon from Jackson Hole, Wyo. has been examining the brains of grizzly bears for the past year. Within nine months to a year, Stevenson and a team of neuroscience students hope to publish a "rough" atlas of the grizzly bear's brain.

What he's seen to date is fascinating, Stevenson said earlier this week.

For example, a grizzly bear's nose is highly developed - thousands of times more developed than a human's, and far better than the best tracking dog's nose.

"They have the greatest olfactory (mechanism) on earth," Stevenson said.

He said the portion of the grizzly brain that governs smell looks like a golf ball with porcupine quills running out of it.

Those quills are nerve endings that run to another part of the grizzly's brain - the gray matter where memories are stored.

Grizzlies, compared to other animals, have a lot of gray matter, Stevenson notes. That gray matter allows grizzlies to remember where food and shelter and all the other necessities of life are - via smell.

"We're very impressed with the olfactory systems of bears," he said. "I think they smell their way through life."

Stevenson's research corroborates other studies of bears. Grizzlies have been known to travel for miles - sometimes more than hundreds of miles - just to reach a prime berry patch.

Bears are also known for having a knack for finding their way home. Past management bears have been caught from, say, the North Fork of the Flathead, moved a long ways away, only to return within a week.

How do bears find their way?

Smell, Stevenson theorizes. They use smell to remember places. Just like you remember the smell of your mother's pancakes for breakfast, a bear uses smell to remember exact locations of its last good meal. And that meal may have been three years ago with mom on a favorite mountainside in June.

"Olfaction memory is a big thing in grizzly bears," he said.

Stevenson's findings are not necessarily surprising, but they are "fascinating," said Chris Servheen, the grizzly bear recovery coordinator for the U.S. Fish and Wildlife Service.

"No one has ever looked at bears the way (Stevenson) is doing it," Servheen said. "We're lucky to have someone like George doing this."

Servheen said the research, at least now, doesn't have much impact on the way bears are managed, other than giving biologists a better view of the thought process of bears. But who knows? Somewhere down the line it could have management implications.

Stevenson is also looking at the pituitary glands of bears and how it connects with the brain. The pituitary gland is the part of the brain that would control hibernation.

He said it's too early to say for sure the pituitary gland is better developed in bears, but he suspects that it is - at least in some species. Hibernation is a natural biological mechanism that allows bears to have and raise young and save energy through the winter months.

But not all species of bear hibernate, Stevenson notes. Tropical bears for example, don't hibernate. Even some North Fork grizzly bears don't appear to hibernate - or if they do, they don't hibernate for long.

Temperature and the way the bear's brain senses temperature changes may actually start the hibernation process, Stevenson theorized.

Stevenson to date has looked at six different grizzly bear brains. They come from management bears - bears that would be normally euthanized because of management concerns, such as depredation or continual raids on human dwellings or households or bears that are accidentally killed.

No bears are killed for the study.

The study is being completed in cooperation with U.S. Fish and Wildlife Service and Montana Fish, Wildlife and Parks.

Stevenson is donating his time and effort to the project, with the hope that some institution will finance the publication of the atlas when its completed.