Yellowstone’s Summer 2010 Bison Population Estimate Released

Yellowstone National Park has completed its annual summer bison population abundance estimate.

The population is estimated to be 3,900 bison. The estimate is based on a series of aerial surveys conducted in June and July.

This year’s calf production represents 15 % of the population. Fifty-six percent of the bison are distributed across the Northern Range this summer, while the remainder are found in the Central Interior herd.

The population was estimated at 3,300 bison last summer; and at 3,000 adult and yearling bison in late winter. The peak population estimate of 5,000 bison was recorded in the summer 2005.

The observed rate of population change this past year is within the natural range of expectation for wild bison. The rate at which wildlife populations increase in abundance is a reflection of the combined effects of reproduction and mortality, and is heavily influenced by age structure of the population, and habitat conditions encountered over the course of time.

This population estimate is used to inform adaptive management strategies under the Interagency Bison Management Plan (IBMP). Specific management actions may be modified based on expected late winter population levels as corroborated by the summer population estimate.

The IBMP is a cooperative plan designed to conserve a viable, wild bison population while protecting Montana’s brucellosis-free status.

The cooperating agencies operating under the IBMP are the National Park Service, the U.S. Forest Service, the Animal and Plant Health Inspection Service, the Montana Department of Livestock, the Montana Department of Fish, Wildlife and Parks, the InterTribal Buffalo Council, the Confederated Salish Kootenai Tribes, and the Nez Perce Tribe. More information on the IBMP can be found at http://www.ibmp.info/.