Yellowstone Bison Numbers Down Sharply
BILLINGS, Mont. The number of bison in Yellowstone National Park has declined sharply since late last summer, when the population hit a documented high of 4,900. A park spokesman attributed the drop to the hundreds of bison captured and sent to slaughter and to normal winter deaths.
But Al Nash said Friday the new population estimate -- 3,500 -- is in keeping with what park officials anticipated, considering the captures, and that there continues to be a "large, viable wild population of bison in Yellowstone."
In 2003, the late-winter bison estimate was 3,100 animals, he said. By late summer in 2004, the population had grown to more than 4,200, he said.
The new population estimate, released Friday and based on an aerial survey, is still above the target population of 3,000 contained in a state-federal plan for managing bison that leave the park and enter Montana. Josh Osher of the activist group Buffalo Field Campaign, dismisses the target as politically based.
"There's no scientific validity at all in that number," said Osher.
During the first two months of the year, nearly 940 bison were captured near the park's northern boundary and most of those animals were sent to slaughter without first being tested for brucellosis, the disease central to the management plan.
Montana ranchers fear that wandering bison could spread brucellosis to cattle, jeopardizing the state's prized brucellosis-free status. Animal rights advocates counter that while brucellosis is found in the bison herd, the risk to domestic cattle has never been proven.
The late-winter estimate takes into account the bison captured as part of management activities, scientific estimates of winter mortality rates and other factors, park officials said. Nash said officials figure winter mortality typically at about 9 percent of the population.
A loss of about 500 more bison, which would bring the population to an estimated 3,000, would prompt discussions among state and federal officials about how best to deal with any migrating bison to limit the impact on the herd size, Nash said.
Osher said the population estimate doesn't matter as much as how the animals are doing, how they are using their habitat and how management actions might affect their dynamics.
Source: Associated Press