Learning About Bears
Biologists have devised numerous means to study the elusive and shy black bear. One of the most common ways is to try to capture the bear by luring it to a trap with bait.
Once the researchers tranquilize the animal, they put a radio collar on the bear that will emit radio signals that can be picked up with receivers from the ground or air.
Once the bear is released, biologists can follow the animal and also detect when it is active or resting.
Trapping bears can be tough. It's often easier to find the bears in the winter when they are sound asleep in their dens if you can find the den! Finding dens can be a challenge in Idaho, they are usually far from roads and human settlements. Biologists begin monitoring bears in October, looking for a bear that is returning often to a certain site.
When the radio collar signals indicate the bear is resting a lot, biologists figure that the bear has denned. They mark the site on the map, and then use snowmobiles, snowshoes, or skis to reach the den later in winter while the bear is in its deep sleep.
At that time, the researchers can usually remove the bear, replace the collar with one containing fresh batteries, and collect data. When they are done, they return the bear to its den and cover the entrance again with snow.
Data collected from hibernating bears has provided clues to several human ailments. For example, black bears may possess a clue that may help prevent bone disease in humans. Many humans develop osteoporosis as they get older and less active. Their inactivity causes bones to lose calcium and weaken. This happens in most mammals that are inactive for long periods of time, but it doesn't happen to black bears. Even after sleeping six months, their bones are as strong as the day they curled up for the winter. What's the difference?
Black bears, like other animals, lose calcium from their bones during this period of inactivity. But, unlike other inactive animals, bears don't urinate when they hibernate. Their waste products are broken down into substances that their bodies can use again and calcium is reabsorbed. If scientists can discover how this occurs, they may be able to create a method for preventing osteoporosis in humans.
After a radio-collared bear emerges from its den, biologists can follow its movements and activity. They plot the bear's locations on topographic maps, and then they compare the locations with information about that area's habitat. To classify bear habitats, they separate major types using aerial surveys. For example, they can see where a clearing is, where a stream flows, where trees are particularly dense. Then they go to these areas on the ground and identify the plants growing in these major habitat areas.
To determine daily patterns, they monitor a bear at hourly intervals for 24 hours. The signals change if the bear is motionless for more than two minutes, thus indicating to researchers that the bear is resting. In this way they can create a picture of what a bear does each day throughout the year.
"To study bears, we often have to capture them. As with any animal capture study, we encounter bears who are trap-shy. At Priest Lake, one female often bedded within 50 yards of a trap. She would feed near the trap, but never attempted to eat the bait we placed in the trap. She was exceptionally wary, and we caught her very few times during the study. It was enough to make us feel personally rejected."
- John Beecham