The semi-annual estimate of the Yellowstone National Park bison population is out, now pegged at 3,900 bison -- up significantly from last summer's estimate of 3,300 bison, but far short of the peak population of 5,000 in 2005.

The population figure is well within the expected range of the Yellowstone National Park bison population, which does tend to fluctuate given many variables, including the age structure of the population and habitat conditions encountered over the course of time. The population's age is well within expectations as well, with this year’s calf production representing 15 percent 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 current population is up over the 3,300 bison estimation released by the National Park Service last summer and 3,000 adult and yearling bison in late winter. The peak population estimate of 5,000 bison was recorded in the summer 2005.

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.

RELATED STORIES: Yellowstone Bison Population Up This Winter; Yellowstone Bison Population Up Slightly, Remains Steady; The numbers hold up in 2008; Park officials defend bison numbers

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