Visiting bear dens — a day in the life of Washington’s bear biologists

For the past seven years, our statewide bear specialists, Lindsay Welfelt and Rich Beausoleil, have been conducting long-term population research on black bears, including monitoring hibernating black bears in the North Cascade mountains. If you’ve ever wondered what it takes to further the science around black bear monitoring, here’s a deeper look into the project they’ve been working on.

Breaking trail

To get to a bear den, you must hike through waist-deep crunchy snow. You also have to move around as quietly as possible because while bears are hibernating they can still be alert and hear unfamiliar noises. If the researchers do not stay quiet and approach cautiously, the bear may leave the den.

This day, we were able to snowmobile about 200-meters from the den. You might think that 200-meters is a simple endeavor but add to the situation high elevation (around 4,000-feet), waist-deep snow, backpacks with gear, and the need to be quiet, and it becomes pretty complicated pretty quick.

Photo one: Lindsay holds radio telemetry device to locate the den. Photo two: This bear den is in the Glacier Peak Wilderness near Leavenworth, Washington.

In order to find the black bear, biologists use a system called radio telemetry. WDFW biologists collared this female bear with a GPS transmitter two years ago, and the collar reports the bear’s movement every six hours. But the battery-saving technology doesn’t share the den’s exact location. To locate the bear, the biologist holds up a satellite-looking contraption that gets louder the closer you get to the collar. It’s a needle in a haystack, but as they approach, the signal gets louder and louder until we are 10-meters away.

Finding the den

We find the den. Rich begins digging into the snow. He must do it quietly, so he doesn’t startle the female bear or her yearling or yearlings. Once he creates a large enough hole, he slowly slides into the den head first, and darts the female with a sedative. The dart gun he uses operates with air, causes minimal impact to the bear, and barely makes a noise when fired. As Rich says, we want to leave the bears as good as, or better, than we find them.

Once the mother bear is fully asleep, Rich darts the yearling. It takes about 10 minutes for both bears to be fully sedated. The next step is to gently remove the bears from the den and take measurements.

Lindsay displays the dart gun.
Rich and Lindsay remove snow from the den entrance. Rich enters the den head first to dart the female.

By the numbers

A huge ball of brown fur emerges from the den as Lindsay carries the bears out of the den, one at a time. Last year, Rich and Lindsay placed a camera at the den when the female had newborns so they could count the cubs (WDFW biologists avoid disturbing dens with new cubs). At that time, photos showed that she had two cubs. But today, there is only one yearling — 50 percent of litter survival isn’t bad for a first-year mom. Once they remove the bears from their den, they add blindfolds to help keep the bears calm.

Lindsay and Rich remove the yearling from the den and lay him on a green sling. They will keep the bear on the sling until they put him back in the den.

Lindsay places the bear on a green sling and attaches a scale. Rich lifts the bear, and they determine that she weighs 110-pounds. He explains that female bears with cubs can lose up to 40 percent of their weight during hibernation. This female weighed 120-pounds two years ago, and because she’s only six-years-old, Rich tells me she’s healthy. She likely weighed 140–150 pounds in the fall when she began to hibernate, which is right at average for an adult female bear in Washington

Photo one: Bear GPS collars. Photo two: Lindsay removes the female’s collar and replaces it with a new one.
The cotton on the collar that will rot away to keep from harming the bear.

Because we captured the female two years ago, it’s time to change her collar. Lindsay removes her old collar and replaces it with a new one. The collars have a piece of cotton that connects the two ends of the collar. If the collar’s electronics fail, and biologists aren’t able to find her again, the cotton will rot away and the collar will drop off the bear. She won’t have to carry the collar around forever — no harm done.

Rich checks the yearling’s teeth. They are in great shape.
Rich takes the yearling’s paw and head measurements.

The male yearling is 34-pounds, a healthy weight according to Rich. They take the male’s measurements and check his furry belly to see if he has a chest blaze. A chest blaze is a distinguishing mark on bears — typically it’s white or blonde — and biologists can use these markings to help identify individual animals. Rich also checks the yearling’s teeth and fits it with its own collar.


Once they’ve added collars and taken measurements, the final step is to examine the den itself. Lindsay shows me how they document tree cover, aspect of the slope, and den condition. In this den, the female did not add any leaves or sticks for insulation — somewhat unusual for bears as they usually line the den with vegetation. We also record the den latitude and longitude, so when we’re back in two years we have a head start locating where these two may be.

The den entrance and a view from inside.

Back to their long nap

It’s time to place the bears back in the den. Rich puts a dab of Douglas fir oil on their muzzle, so the first thing they smell when they wake up is a natural (not human) scent.

Lindsay and Rich put the bears back in their den. Then they use a pile of tree branches and snow to cover the entrance.
Female bear has a new collar, and biologists return her to the den.

The biologists gently place both bears back in the den next to each other. Then, they cover the den entrance with evergreen branches and snow, leaving it as close to the way we found it as possible. The two should be nice and insulated until they wake up this spring.

Research and science

Work like this helps the us understand how bears are faring in the wild so we can maintain stable bear populations throughout the state. Black bears are native to Washington and the most widely distributed bears in North America. We’re working to keep them on the landscape for generations to come.

Keeping bears wild

It’s not safe or practical for the public to have the unique experience of visiting a bear den. And since bears tend to avoid humans, seeing one in the wild is a pretty neat experience. As bears begin waking from hibernation this March and April, follow these tips to keep you safe and give them their best chance of survival:

· Never intentionally feed bears or other wild animals.

· Always keep garbage cans in a garage or sturdy building until collection day.

· Take down seed and hummingbird feeders until winter.

· Clean up fallen fruit or other possible attractants around your home.

· Remove pet food from wildlife accessible areas, and feed pets inside.

· Thoroughly clean barbecue grills after each use and store them in a secure building.

· Cage and electric fence your domestic fowl and livestock pens. Watch this video to learn more about animal husbandry. (link)

· Avoid storing food in your car.

Thank you for helping us keep wildlife wild!

Sam Montgomery is a communications manager at the Washington Department of Fish and Wildlife. You can contact Sam at



The Washington Department of Fish and Wildlife

The Washington Department of Fish and Wildlife is dedicated to preserving, protecting and perpetuating the state’s fish and wildlife resources.