Three cougars that decimated the bighorn sheep population on a Montana Island have been killed. Before wildlife officials tracked them down, the predators had killed over 70 members of the prized herd.
The Montana Fish, Wildlife, and Parks Department announced this winter that one adult female and two adult male lions were euthanized on Wild Horse Island to help protect both the sheep population and visitors from further attacks.
According to the department, bighorns have no way of evading predators on the 3.4-square-mile island. So there was no chance that any of the remaining animals would survive much longer.
“I think what people don’t really realize is that Wild Horse Island has almost no escape terrain for bighorn sheep,” Neil Anderson, regional FWP wildlife program manager, said. “So, they’re pretty vulnerable to predation. To have that many mountain lions on the island, they could do a pretty good number on the sheep.”
No one is sure just how the cougars made it to the island. But some believe that they either swam or walked across an ice bridge during the winter. And once the animals had access to the sheep, they hunted them down to the lowest sheep count reported in two decades. As it stands, officials estimate that only 35 sheep remain.
“That’s what groups of people have seen,” Anderson continued. “We haven’t done a flight (survey) yet.”
Montana has used the island to protect bighorn sheep for decades, and after the cougar attacks, officials may have to relocate animals from other herds to help replenish the population. It is the first time in 30 years that such measures have been needed.
Bighorn Herd That Was Attacked By Cougars Had Lived on the Montana Island for Over 7 Decades
The Wild Horse Island bighorn population originated in 1939 when Montana introduced two sheep to the area. And since then, the animals have flourished because very few predators hunt on the island and there are no documented diseases.
Over the years, the Montana State Parks has only needed to add ten sheep to the herd. And the last time that happened was in 1987 when two were transplanted from Lincoln county.
The parks department aims to keep 100 to 120 bighorns on the island to protect the ecosystem. And in 2019, it counted around 130. So 26 of the animals moved to another location.
But shortly after the population began to drop dramatically. And because no live animals showed signs of illness, officials knew predators had made their way to Wild Horse Island.
“It started going down pretty significantly after that,” Anderson said. “The logical explanation is predation.”
In 2019, Flathead Lake, which surrounds the island, frozen over for the first time since 1990. The parks department believes that have the cougars the perfect chance to make it to Wild Horse.