There is nothing typical about the pikas living on the icefields of the St. Elias Mountains. For one, they survive on nunataks -- isolated islands of rock rising out of the glaciers in a region famous for its storms and extreme weather.

Clinging to steep tiny meadows near the tops of the nunataks, these tiny mammals also have a most un-pika-like diet. Since favourite foods like willows and sedges are in short supply, they have learned to expand their menu; they still eat plants, but they also eat dead birds -- brains and all.

During spring and fall, storms blow migrating songbirds onto the icefields where they often die on the glaciers. The stocky little pikas scurry onto the glaciers and collect the dead birds, just as they collect alpine plants for drying.

"It's like manna from heaven that flies in every year," says David Hik, an ecology professor at the University of Toronto who has studied the pikas for several seasons. "Sometimes they even stack the birds like cordwood in their haypiles."

"We know that the pikas are eating the brains of the birds because of the neat little holes chewed in the back of their heads. Most animals, when they eat a carcass, will go for the guts and the brains. They're high in fat and proteins, and they're easily digestible."

Hik first went onto the icefields in 1991 as part of a research group trying to catalogue all the plants and animals living on the nunataks, part of a larger effort to determine how global warming might affect northern alpine ecosystems.

"When you're out there it's a fairly stark environment and even a blade of grass catches your eye; but there are numerous protected meadows that support plants, insects, even nesting birds. And to me, the most remarkable aspect is the small mammals living on those isolated nunataks."

He returned to the icefields to learn more about the collared pikas, and is the first scientist to study them in detail. This species lives in the Yukon, Alaska and northwestern British Columbia, and is one of two North American species of pikas.

Scientists and mountaineers have reported seeing pikas on nunataks in the St. Elias Mountains for the last 50 years. While other mammals live at the margins of the glaciers, Hik says collared pikas are the only mammals known to live year-round in the central icefields. They are also the only North American pikas known to eat meat.

Pikas are lagomorphs, the Order that includes rabbits and hares. Field guides will inform you that pikas are herbivores. They use their chisel-shaped front teeth to harvest huge quantities of grass, enough to last them all winter. Even their digestive systems mark them as vegetarians as they ferment food in their guts.

Hik says that at first other biologists didn't believe his stories about the meat-eating pikas. "I was saying, 'Isn't this neat' and asking whether anyone else had observed anything like this, and the response was 'You're crazy.'"

Hik knows that pikas are eating the birds because his research team has analyzed hair and feces from the pikas, and used a technique called stable isotope analysis to determine what they have been eating. He wants to figure out how much of the pikas' diet is made up of bird meat.

Bird brains are obviously a delicacy for the pikas, and might affect their ability to survive and reproduce on these isolated nunataks. Hik is trying to determine the importance of this meat supplement by comparing the icefield pikas with two other groups of pikas living in Kluane which eat more traditional fare.

These pikas -- living in the Ruby Range and near the Slims River -- make their homes in talus slopes next to alpine meadows where plenty of alpine vegetation is close at hand. Even if there were dead birds in the area, Hik says that arctic ground squirrels would probably eat them before the pikas had a chance to do so.

Hik cannot imagine pikas living in a more extreme environment than the icefields, where there might be only 30-40 snow-free days every year. Just surviving is hard enough, particularly for animals that do not hibernate.

He has evidence that the pikas actually travel on the glaciers. As most nunataks can only support one pair of pikas, juveniles face a major problem when they're kicked out of the family home. Like intrepid arctic explorers, they must set off across the ice to find another meadow. In the St. Elias Mountains, this can mean a long, lonely trip.

"Try to imagine a 160-gram animal storing enough resources to disperse over ten kilometers of glaciers. It is hard to imagine it. The birds might be an important food source for them as they are scattered across the glacier. But how they would find them I have no idea," says Hik.

Hik's work is part of a larger effort to determine how global warming might affect northern alpine ecosystems. For more on this subject, look for the December issue of National Geographic magazine as its cover story is on the St. Elias nunataks. Or you can contact Prof. David Hik at the University of Toronto at Scarborough, Division of Life Sciences, Scarborough, ON, M1C 1A4.