Snowy Peril. The downside for mountain goats? What lurks above? Mountain goats are high elevation daredevils, learning to balance upon the steepest rocky edifices soon after they are born.

While the precarious perches help goats avoid being eaten, there is an obvious downside to these sanctuaries : avalanches.

While scientists have long suspected that this life on the edge was risky, they have not really understood the extent to which avalanches affect mountain goats, and whether they instinctively shun, or can learn to avoid, avalanche-prone conditions.

While the behavioral question remains a mystery, a study published in the journal Communications Biology, shows that cascades of snow are a major killer, substantially affecting the animals' population.

Kevin White, an ecologist at the University of Victoria and the University of Alaska Southeast and lead author of the study, said, '' We've often thought of snow as a major-driver of populations,'' of mountain goats.

But the difficulty of studying their rugged, inaccessible habitats has limited understanding of what avalanches do to the animals' numbers.

Over 17 years of field work with the Alaska Department of Fish and Game, Mr. White fitted radio collars on 421 goats in various regions of southeastern Alaska.

He surveyed the animals' locations, following their movements from aircraft as the collars indicated whether the goats were alive or dead. When mortality was detected, Mr. White swooped in by helicopter.

When, it fit was safe to land, he gathered post-mortem clues. Then he worked with a group of colleagues to make sense of the mortality data.

Data from the collared goats revealed that snow slides barreled down not just on inexperienced kids but on adults as well. Avalanches caused 65 percent of all deaths in one of the regions studied.

In southeastern Alaska overall, '' It could mean that 8 percent of the population, on average, is dying from avalanches; and in some of the worst years, it was over 22 percent,'' Mr. White said. [ Lesley Evans Ogden ]


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