Scientists say the wolves of Isle Royale National Park may go extinct because they are dangerously short of females.
Wildlife biologists John Vucetich and Rolf Peterson of Michigan Tech University say they counted 16 gray wolves on the Lake Superior island this year, and just two, at most, are adult females.
"It's usually 50-50, or pretty close," says Peterson. "But we've had a lot of mortality with the females, especially in 2009."
Why the high mortality among females? It's uncertain.
"Back in the early 90s," Peterson continues, "we had only three females, but it's never been this low."
The overall wolf population is the lowest since 1998, when it was 14.
Unless the females successfully raise pups before dying, the entire population could disappear. Their plight raises the question of whether the park should bring in more wolves.
The population has averaged about 23 since wolves migrated over a frozen Lake Superior to Isle Royale from the Canadian mainland in the late 1940s.
Peterson says Lake Superior used to ice over one in every three years; recently, it's been one in 15, so it's less likely that wolves will be able to naturally migrate to the island.
If the females were to die out entirely, the National Park Service would have to approve the transporting of females to Isle Royale. That's never been done.
Wolves on average have a life expectancy of 4-5 years in the wild, although some live to be 10-11 years old, Peterson says.
Scientists have studied their predator-prey relationship with the island's moose for more than a half century.