300 bison released at Yellowstone

BILLINGS – Authorities at Yellowstone National Park have released most of the 300 bison that had been held on fenced-in pasture for nearly a month, a park spokesman said Monday. Officials hoped the greening grass would keep the bison from straying outside the park in search of forage.

Al Nash said a few bison remained at the Stephens Creek holding site, including some cows with calves and some that appeared close to giving birth. He said officials planned to move those animals from the area separately to allow them to move at a slower pace and to minimize stress on the bison.

The bison had been held at the Stephens Creek site, just inside the park’s northern edge, since March 22, when they were captured to keep them from migrating into Montana for forage.

The hazing and capture of bison is allowed under a state-federal management plan aimed at reducing the potential spread of the disease brucellosis from bison to cattle in the state. Brucellosis is a disease that can cause cows to abort. It can be spread by direct contact with infected animals or an area contaminated by such things as the birthing materials or aborted fetuses of infected animals, according to the state Department of Livestock.

Nash said the park put in place protocols to deal with the potential for transmission among the captured bison. For example, he said, onsite personnel segregated bison that appeared ready to give birth, disposed of matter left behind and disinfected the area with a chlorine bleach solution.

He said he did not know if similar actions were taken in previous years when bison also were held temporarily at Stephens Creek.

So far this year, 1,255 bison have been captured near the park’s northern boundary, and 849 of those were sent to slaughter, Nash said. Several animals died in the past few weeks in holding at Stephens Creek, and Nash said he knew of two instances in which cows aborted fetuses.

Several dozen bison have been sent to slaughter after being captured near the park’s western boundary.

The bison management plan lists 3,000 as the target bison population. The late winter-early spring estimate released by the park in early March put the population at about 3,500. Heading into winter, the population was estimated at 4,900, a documented high.

Dan Brister of the Buffalo Field Campaign said he worries about the stress being put on the bison. He believes park officials could have released the bison earlier than they did. But Nash said officials waited until they believed forage and green-up conditions were sufficient to allow for a successful release.