State and tribal wildlife officials lethally removed three adult mountain lions from Wild Horse Island on Flathead Lake this winter, euthanizing the large cats because they had grown habituated to people and were preying on an isolated population of bighorn sheep used for herd augmentations across the West.
Bears and lions have been sporadically documented on the island over time, and can access the land by swimming or by crossing the sprawling lake on the rare occasion that it freezes. However, the density and habituated behavior of these three lions on the 2,163-acre island warranted immediate removal before they presented a public safety hazard, according to wildlife managers with both the Montana Fish, Wildlife and Parks (FWP) and the Confederated Salish and Kootenai Tribes (CSKT).
According to FWP Region 1 Supervisor Jim Williams, who is a world-renowned mountain lion expert, an adult male lion can have a home range close to 150 square miles, and even juveniles explore wide-ranging territories that dwarf Wild Horse Island, which by contrast is approximately three square miles in size.
“To have three adults concentrated on three square miles of land is probably one of the highest temporary densities of mountain lions on planet Earth,” Williams said Friday.
The management action was prompted by reports from property owners earlier this winter that the large carnivores were caching prey beneath the decks of homes and cabins, officials said. The lions — two males and one female — were removed with the aid of hounds on three separate trips to the island, officials said, adding that they returned to the island on two follow-up trips, but did not detect any evidence of mountain lions.
According to FWP Region 1 Spokesman Dillon Tabish, the uptick in visitation to Wild Horse Island in the summer months gave the management action an additional degree of urgency.
“We had reports from landowners on the island that these lions were coming up on their decks and stashing carcasses,” Tabish said. “These particular lions had grown extremely habituated to people, and presented a real public safety issue.”
FWP and CSKT officials were also concerned about the impact the lions could have to one of the nation’s most important conservation herds of Rocky Mountain bighorn sheep, which have persisted disease-free on the island for nearly a century. Although Wild Horse Island provides high-quality habitat that supports a sheep population that has produced some of the largest rams in the world, the animals have no escape route from mountain lions in an island environment, Tabish said.
In the last half-century, more than 560 sheep have been translocated from Wild Horse Island to establish new herds and augment existing populations across the U.S. For example, last year FWP moved 26 bighorn sheep from the island to the Tendoy Mountains in southwest Montana to help reestablish a herd in that area. Since then, however, the population numbers have declined.
“Right now we estimate a sheep population of about 35, which is down from our management goal of 100 or 120 sheep,” Tabish said.
“Alongside prioritizing public safety, we felt it was important to protect one of the few disease-free bighorn sheep herds because of the role it plays in the greater conservation of the species across North America,” added Neil Anderson, FWP regional wildlife manager. “Due to the lack of escape terrain for bighorn sheep and the number of lions on the island, the bighorn population has been reduced to a number we haven’t seen in decades.”
Tabish emphasized that northwest Montana is home to a healthy and robust population of mountain lions, and that the decision to lethally remove them aligned with FWP’s long-standing policy against relocating a habituated mountain lion. Previous research shows lion relocations are largely unsuccessful in preventing the lion from returning, and can create new territorial conflicts with other lions, he said.
The lion hides and skulls from Wild Horse Island were transferred to the CSKT for educational use.
“Mountain lion and other cats, like the bobcat, hold significant cultural importance to Tribal members, and are not hunted within the Flathead Indian Reservation,” said Kari Eneas, CSKT wildlife manager. “Our mountain lion populations are healthy and, in this unique situation, we considered the habituated behavior and density of animals of all wildlife species on the island in our cooperative decision with FWP.”