On Wednesday night around 6:30 p.m., a semi-truck collided with a herd of bison north of West Yellowstone, resulting in the death of 13 bison.
According to Gallatin County Sheriff’s Office Sergeant Dan Haydon, a large herd of bison normally migrates from Yellowstone National Park into the West Yellowstone area using the road corridors and groomed trails. The truck was traveling northbound in the dark near mile marker four on U.S. Highway 191 and became disabled after striking the group of bison. No human injuries were reported, and the truck was towed to clear the roadway.
“A number [of bison] were immediately deceased,” Haydon said. “More were so severely injured that they needed to be dispatched by responding officers.”
When dealing with wildlife collisions, it’s typical for officers to assess whether the injuries are survivable for any animal, according to Haydon. The impact force from the semi was too great for animal survival, and the officers euthanized—or “dispatched”—several of the injured bison, bringing the herd’s death toll to 13.
Haydon said this is the most significant vehicle collision with bison that he’s aware of in the recent past, considering the number of animals involved. Unfortunately, similar events are more common with elk farther north along Highway 191 between Gallatin Canyon and Gallatin Gateway.
“The key is, when visibility drops from darkness or weather conditions, you need to make sure you’re driving at a slow enough speed that you can react to obstacles in the roadway,” Haydon said, although he said it’s unknown whether the semi’s speed was a factor in the collision.
The eyes of bison do not reflect headlights, making the dark animal very difficult to detect at night.
“This is obviously a terrible thing to have so many animals be struck and killed,” Haydon added. “People operating vehicles at a slow and safe speed are really helpful to protect animals in that area.”
A Dec. 30 press release from the West Yellowstone police department suggested that road conditions this time of year often require travel below posted speed limits, and drivers not drive faster than they can stop in the distance their headlights project.
A pair of passenger vehicles were initially reported to have also collided with the bison, but the press release clarified that the other two vehicles were “secondary incidents.”
“We are always saddened by any of these incidents, especially when so many animals are lost,” the release stated.