Utah Division of Wildlife Resources

Bear denning in the south Book Cliffs

Last month, Division of Wildlife Resources personnel, in company with wildlife students from USU-East, traveled to the south Book Cliffs to visit the den of a sow black bear that was believed to be with cubs. Normally, a black bear gives birth to cubs every other year from the time she is 4 1/2 years old. Litters generally consist of one or two cubs.

USU-East wildlife students trek to a bear den in nasty weather.

The denning party of 25 people left Price shortly after 8 a.m. on a Saturday morning and arrived at the bottom of Nash Canyon in the South Book Cliffs before noon. The group began their hike in a snowstorm with several inches of mud underfoot.

This particular black bear has been radio-collared from the time she was a yearling. She is now five years old. The approximate location of her den was plotted on a map from an airplane using a radio receiver and antenna. DWR Wildlife Biologist Brad Crompton used the same equipment to search for the den at ground level that afternoon.

As the afternoon wore on, mud turned to snow and the snow became deeper. The ground was littered with mountain brush, rocks, logs, boulders and patches of slippery clay soil.

After 3 1/2 hours of strenuous hiking, Crompton found the den by waving his radio antenna back and forth and moving in the direction of the loudest electronic pulse. The den seemed to be in a boulder field at the top of a side canyon. Crompton popped his head inside a rock crevice to see if it was occupied. He saw a sow bear and estimated her weight to be somewhere between 150-175 pounds.

Once mama bear was sedated, biologists were able to replace her collar safely.

Based on her weight, Crompton prepared a tranquilizer dart with enough ketamine and xylazine to put her to sleep. After loading his CO2 pistol, Crompton turned on his headlamp and belly-crawled into the den (armed only with the air pistol).

Crompton found mama bear awake, watching him as he entered. As she saw the biologist pull himself inside, she retreated toward the rear wall. With only one chance to shoot, Crompton took careful aim and fired the dart into her haunch. After several tense minutes, she settled into a sound sleep.

After the bear’s breathing became slow and deep, Crompton crawled up to her to replace the radio collar. He passed the cubs out of the den to give him enough room to work. The college students standing near the entrance were more than happy to tend the cubs that looked like two-pound puppies. We estimate that the cubs were three weeks old, or possibly even younger because their eyes hadn’t opened yet.

After Crompton fitted the bear with a new collar, he called for the cubs. They were passed through the den opening and returned to their mother. Crompton back-crawled to the entrance and stood up.

The group, still excited from seeing the cubs, faced the grim reality of a return hike down a slippery slope. Wet snow and saturated clay made the descent even more treacherous than the climb.

Josiah Safely cradles a bear cub from the south Book Cliffs during a study in March, 2013.

DWR wildlife biologists visit the dens of collared females each year to check for newborn cubs and year-old bears that will often den with their mothers. Reproductive success and cub survival data are used in combination with harvest success and other factors to judge population trends. Radio collars enable wildlife biologists to track animals so they can learn more about habitat and home range.

Some of the information for this post was contributed by DWR Wildlife Biologist Brad Crompton and USU-East Wildlife Club President Josiah Safley.