Black Bears in Rocky Mountain National Park: Few, but Growing

A black bear. The park's population is small but has room to grow. NPS.

The question

Across most of North America black bear numbers are stable or rising. But studies from 1985–1991 found only about 20 bears in Rocky Mountain National Park — one of the lowest densities and reproductive rates ever recorded — because so much of the park is tundra and high forest, with few berries and other rich foods. How big, stable and healthy is the population now?

The study

Roger Baldwin and Louis Bender of the New Mexico Cooperative Fish and Wildlife Research Unit combined several methods:

• snaring bears, anesthetizing them and fitting radio collars for tracking;
• remote cameras every five kilometers across the park to spot uncollared bears;
• visitor reports of bears;
• den checks to count cubs and their survival.

Measuring a bear's foot. NPS.

Results

• 14 bears collared: four adult males, four adult females, two subadult males and four subadult females (one to three years old).
• Cameras found five more bears west of the Continental Divide and six east of it.
• With visitor reports, the park held at least 20 to 24 bears.
• Four bears died during the study — two legally hunted on neighboring land, two of unknown causes. Overall survival from 2003 to 2006 was 93%.
• Sixteen cubs were seen across old and new studies, about 1.8 per litter. Cub survival rose from 43% in 1985–91 to 71%.

What it means

Density is still among the lowest recorded, but the population could grow substantially over the next 10 years. Bears are heavier and better nourished than in the earlier study — possibly from eating more human food — and are using more human-use areas in their home ranges. That is a warning sign: bears habituated to human food can become aggressive in getting it, and such "problem bears" are usually euthanized.

Sources

Based on "Black Bear Population and Stability," by Darin Newton, Rocky Mountain National Park, National Park Service; a work of the United States government in the public domain. The summary is not a statement of park policy.