Yellowstone Late Winter Bison Population Estimate Released

Date: March 9, 2007
Contact: Nash, [phone]
Contact: Vallie, [phone]

Yellowstone National Park has completed the 2007 late winter bison population estimate. The late winter population is estimated to be 3,600 bison. 

The estimate is based on a late winter aerial survey. It takes into account the 2006 late summer population estimate of 3,900 bison, known brucellosis risk management mortalities and scientific estimates of over-winter mortality rates.

The population estimate is used to guide 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 annual late winter estimate.

This is the seventh winter the IBMP has been used to guide brucellosis risk management actions.

The IBMP is a cooperative plan designed to protect Montana’s brucellosis-free status while allowing for the conservation of a viable, wild bison population. Protecting Montana’s brucellosis-free status requires keeping bison from mixing with cattle grazing on land outside the park.

The five cooperating agencies operating under the IBMP are the National Park Service, the U.S. Forest Service, the USDA Animal and Plant Health Inspection Service, the Montana Department of Livestock, and Montana Fish, Wildlife and Parks.