ANCHORAGE - At least 143 caribou were killed in a devastating avalanche in the Kenai Mountains last winter, according to a biologist who helped count the skulls.
"It's the only incident I've ever heard of where so many animals from such a small herd were taken out," said Rick Ernst, a biologist and pilot for the U.S. Fish and Wildlife Service.
Before the snow slide last December, the Killey River caribou herd numbered about 700 animals.
Several trips to the site, near Skilak Glacier 30 miles southwest of Sterling, turned up bone after bone as summer's brief heat melted most of the snow from the rocky tundra. Biologists made new piles of skulls on each visit to make sure they weren't recounting the same carcasses.
Investigators believe the caribou were traversing a steep, snow-covered ridge near Alpine Lake when they triggered an avalanche that swept the animals about 2,000 feet downhill. The dead animals lay undetected by humans for about two months.
Ernst was the first to suspect something was wrong.
He was flying along the steep ridges bordering Alpine Lake in early March listening for radio signals from 21 collared caribou.
The transmitters issue a distinct mortality beacon when an animal hasn't stirred for several hours, and Ernst picked up five of the tones while observing the snow slide from the plane. He heard four more of the mortality signals on a later flight.
If nine of 21 collared caribou were caught in the slide, he reasoned, there probably were many more.
Investigators helicoptered into the area in May for a first look from the ground and were stunned by the carnage. They saw broken bones poking out of a debris field blanketed in gray fur. Bears, eagles and wolves had feasted on the remains.
Biologists went back in July, and found yet more carcasses revealed by melting snow. Ernst returned one last time Sept. 9 and found more dead caribou.
Even at that time, snow still covered some of the area. So more animals may lie underfoot, and some wounded may have wandered off to die, he said. He described the 143 figure as "a minimum." By now, the valley is under this season's blanket of fresh snow.
Before the avalanche, state and federal biologists were worried about the Killey River herd growing too large and overgrazing its winter forage.
They were encouraging hunters to thin the herd's ranks by about 200.
Ernst said it's too early to say if the caribou deaths will have an impact on next fall's hunt.
A lot of the animals killed by the avalanche were cows and calves, so the herd will take a while to recover, he said.
A new Killey River caribou head count this fall may help biologists from the state Department of Fish and Game, U.S. Fish and Wildlife Service and U.S. Forest Service gauge the situation, he said. The Board of Game meets in March to decide.