BILLINGS, Mont. — The Yellowstone National Park bison population has reached an estimated 4,900 animals -- hundreds more than last winter and the highest level documented, a park spokeswoman said Wednesday.

The population growth is renewing concerns about how federal and state officials manage the bison, some of which carry the disease brucellosis.

Jake Cummins, executive vice president of the Montana Farm Bureau Federation, said Wednesday the population is three times greater than the park's carrying capacity -- what the landscape can successfully sustain -- and that it poses a serious risk to a livestock industry fearful that wandering bison will transmit brucellosis to cattle in Montana.

"Our concern is for the bison population to be reduced to a manageable size," he said. He contends the National Park Service has shirked its responsibility by not "controlling" the herd. But Cheryl Matthews, a park spokeswoman, said officials have seen no measurable effects on the land as bison numbers have grown.

The population was estimated last winter at about 4,200 animals, she said.

Cummins and Steve Pilcher, executive vice president of the Montana Stockgrowers Association, support more aggressive control methods. Cummins said he wouldn't be averse to having "excess" bison killed in the park, but he called Montana's proposed winter hunt of up to 50 bison that wander into this state "silly," in large part due to the small number of animals that could be killed.

Pilcher said he wants the federal government to move as quickly as possible toward eliminating brucellosis.

"Somebody is going to have to show a commitment to doing it," Pilcher said.

Larry Cooper, a spokesman with the U.S. Department of Agriculture's Animal and Plant Health Inspection Service, said brucellosis eradication continues to be the goal.

Some bison in the park have brucellosis, which can cause cows to abort, and other wildlife, including elk in the greater Yellowstone area, have tested positive. Bison advocates have long argued, however, that there hasn't been a documented case of transmission from bison to cattle in the wild.

During the winter, bison often leave the park in search of forage in Montana. When they do, the bison become subject to hazing or being captured and tested for brucellosis under the terms of a management plan carried out by federal and state agencies. Bison that test positive get shipped to slaughter.

The plan also sets a population "target" of 3,000 animals. If the late-winter/early-spring count tops that, officials can take steps to reduce the size, including sending bison that enter Montana straight to slaughter without testing.

Given the current population, that could lead to a lot of dead bison if the area has a hard winter marked by heavy snowfall or ice that push bison from the park in large numbers, said Fred DuBray, executive director of the Intertribal Bison Cooperative.

Amy McNamara, national parks director for the Greater Yellowstone Coalition, a conservation group, called the bison management plan illogical, and said it is time the agencies involved rethink it.

"We can treat bison like wildlife while still protecting Montana's brucellosis-free status and we ought to be focused on that," she said.

During the 2004-2005 season, the state Department of Livestock said 98 bison that left the park's western boundary were sent to slaughter, and 17 were sent to an experimental "quarantine" facility. More than 2,200 bison were hazed and nine were vaccinated against brucellosis, the department said.

Both Matthews and Karen Cooper, a department spokeswoman, said the agencies will continue following the management plan.

Source: Associated Press