Yellowstone Bison Tally At Lowest Level In Decade

The number of bison counted in an aerial survey in and around Yellowstone National Park has dropped to its lowest level since the early 1980s.

Federal biologist Mary Meagher, who has been studying the park’s bison for 38 years, said this week’s count was 1,982. Before the onset of winter, Meagher estimated the herd size as high as 3,500.

The flights never locate all animals, Meagher has said, and there could be more than were counted.

The Park Service and the Montana Department of Livestock have shot or shipped to slaughter nearly 800 bison so far this winter. But the harsh weather is also taking its toll, Meagher said.

“We have a sense that even over a week, it’s tougher, more of a standand-wait-and-endure” situation, she said. “We’re seeing more fragmentation, a cow with a calf, separated young animals not near any other bison. They’ll die.”

Most of the park remains covered in thick crusty snow almost impossible for a bison to break through. And even if spring arrives early, Meagher said, “it will probably give little.”

Meagher blames the park’s groomed snowmobile trails for creating easy pathways for bison that would otherwise have died to leave the park and survive and breed. She estimated the herd at winter’s start was roughly twice what it would have been without the trails.

There were 2,114 bison in the winter of 1984-85, the first year they began leaving the parks. The number peaked in 1994-95 at nearly 4,000.

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