Two pups of the Junction Butte wolf pack in Yellowstone were killed in a collision with a vehicle/NPS

Being comfortable around human onlookers and roads might have played a role in the deaths of two Yellowstone National Park wolf pups that were hit by a passing vehicle in the Lamar Valley, according to park biologists.

The pups, members of the often visible Junction Butte pack, were killed on November 19 when they were struck around sunset on the road between Tower Junction and the Northeast Entrance, a park release announced Wednesday. A necropsy confirmed the black male and female pups died from a vehicle strike. Yellowstone law enforcement officers have been investigating the incident.

During the summer of 2019, the pack of 11 adults attended a den of pups near a popular hiking trail in the northeastern section of the park. Wanting to keep visitors and wolves apart, the park closed the den and surrounding area to the public. When the pups approached the trail and were in proximity to hikers, most people quickly moved away. However, some people violated the required 100-yard distance from wolves and approached the pups when they were on or near the trail to take a photo, the release said. Other people illegally entered the closed area to get near the wolves.

Having grown accustomed to hikers, the pups then came close to visitors along a road.

Yellowstone staff hazed the pups several times over the last five months in an attempt to make them more wary of people and roads. This effort was never fully successful and the pups continued to demonstrate habituated behavior due to continued close encounters with visitors.

“Having studied these pups since birth, I believe their exposure to, and fearlessness of people and roads could have been a factor in their death,” said Yellowstone’s senior wolf biologist Doug Smith. “Visitors must protect wolves from becoming habituated to people and roads. Stay at least 100 yards from wolves, never enter a closed area, and notify a park ranger of others who are in violation of these rules.”