Monitoring of Grizzly Bear Recovery Status

Grizzly bears in the Greater Yellowstone Ecosystem recovery zone and the surrounding 10-mile perimeter area are moni­tored using ground and aerial observations. Radio telemetry is used in efforts to locate the approximately 80 bears that have been equipped with transmitters. To determine whether the grizzly bear population is meeting the recovery criteria, data is collected on grizzly bear mor­talities, the number of individual female grizzly bears with cubs, and their distribution in the 18 Bear Management Units.

Yellowstone

At least 11 distinct females with home ranges either wholly or partially within Yellowstone National Park (YNP) produced cubs in 2008. The 11 females produced at least 22 cubs. Average litter size in YNP was 2.0 cubs per litter. There were 2 one-cub litters, 7 two-cub litters, and 2 three-cub litters observed. Some of the females observed with cubs in the park in 2008 had home ranges entirely within the boundaries of YNP, while others had home ranges that overlapped the park boundary. The annual number of females producing cubs in YNP was relatively stable from 1996 - 2008, suggesting that the park may be at or near carrying capacity for grizzly bears.

Number of different female grizzly bears with cubs-of-the-year observed in Yellowstone National Park, 1990-2008.

 

Additional project information and Annual Reports are available at the Official Yellowstone National Park Website: Bears and the Interagency Grizzly Bear Study Team Website.