Bison in a brucellosis research project will be put in a horse trailer equipped with skis and taken to the interior of Yellowstone National Park.
The seven cows, equipped with radio collars, have been in a pen at the park’s northern boundary near Gardiner.
These bison and hundreds of others entered a National Park Service trap that is part of a temporary plan for dealing with bison that wander from the park. There are concerns in Montana that the bison will spread brucellosis, which causes abortions in cattle and undulant fever in humans.
The trapped animals are tested for the disease brucellosis, with those testing positive going to slaughter. Bison testing negative are held in a corral and are being fed until state and federal negotiators of a bison management plan decide what should be done with them.
As of Wednesday, nearly 1,000 bison had been killed as part of the herd control, either through shootings in the park area or at slaughter. The Montana Department of Livestock said its shooters killed 17 bison near West Yellowstone on Wednesday.
The seven bison are among nearly two dozen chosen for a multiyear research project designed to show how brucellosis affects bison.
Yellowstone Chief Ranger Dan Sholly said the seven will be put in a horse trailer that is equipped with homemade metal skis and will be pulled by a machine used to groom snowmobile trails. The animals will be transported from the trap to Yellowstone’s Mammoth Terraces area in one trailer, and then will be transferred to the ski trailer.
The bison probably will be released near Old Faithful, where thermal features provide warmth and expose some natural food, Sholly said. Because deep snow and ice cover most of the park, grasses that bison eat are concealed and they wander elsewhere to look for food.
Some of the collared bison carry vaginal inserts designed to set off an electronic signal when the animals abort or give birth. Tests in the brucellosis research can then be conducted on these animals.
Scientists have a good understanding of how brucellosis affects cattle, but their knowledge of effects on bison is much thinner.
“We’re trying to understand the natural course of the disease in bison,” said Tom Roffe, the wildlife veterinarian in charge of the research. “How it is transmitted from animal to animal and from generation to generation.”
He began the project in 1995 and hopes to monitor the animals for five years.
Sholly said the National Park Service preferred to haul the bison in a conventional trailer to the Horse Butte area near West Yellowstone and release them on public land. The federal agency in charge of brucellosis eradication, the Animal and Plant Health Inspection Service, approved that plan but the Montana Department of Livestock disagreed, Sholly said.
Some of the bison in the project are pregnant or have been exposed to brucellosis, and Roffe said state livestock officials told him they did not want to risk allowing those animals in the area.
Subscribe to the Morning Review newsletter
Get the day’s top headlines delivered to your inbox every morning by subscribing to our newsletter.