Avalanches, Landslides, Good For Some

Working in a steep valley once in Kenai Fjords National Park, I used an old avalanche chute for a daily commute. With all the trees sheared by a slide the winter before, the chute provided some of the best walking in the valley. Unfortunately, black bears came to the same conclusion. After I bumped into two in one day, I chose a more difficult path through the woods.

The bears' apparent preference for a country cleared by avalanche supports an idea becoming popular with habitat researchers-landslides and avalanches aren't such bad things.

Gordon Reeves and Kelly Burnett, fish biologists with the Pacific Northwest Research Station in Portland, Oregon, have studied the effects of landslides on streams and fish. Though landslides turn a creek brown and clog it with other debris, such as large trees and rocks, what remains after a natural landslide may be beneficial to fish in the long run. Logs provide shelter and feeding holes for fish, and rocks make good spawning areas. Burnett says a natural landslide, unlike one caused by logging, is part of nature's cycle, a pulse of rapid change to a stream system that keeps habitat varied and healthy. Manmade landslides that occur after logging don't include enough big trees and occur too frequently to do fish any good, Burnett said.

At least 30 people in Alaska have died this year due to avalanches, a constant hazard of mountain travel. In areas where the snow retreats, avalanche chutes often look like claw marks on the side of a mountain, the reminder of the incredible force stored on steep slopes.

Though deadly if a person or animal happens to be in the chute at the wrong time, avalanches also seem to attract quite a bit of wildlife. Wolverines frequently were found near avalanche chutes in British Columbia by researchers taking part in the Columbia Basin Fish and Wildlife Compensation Program. When biologists John Krebs and Dave Lewis followed 41 radio-collared wolverines, they found the animals patrolling fresh avalanche tracks more often than not. The wolverines were rewarded with plenty of food in the form of dead animals caught in the avalanches. The researchers also tracked female wolverines to their midwinter birthing dens. They found elaborate networks of tunnels at the bottom of avalanche paths, amid jumbles of boulders and logs.

University of British Columbia researcher Roger Ramcharita followed radio-tagged grizzly bears' spring wanderings in the Columbia Mountains. While avalanche tracks made up only 10 percent of Ramcharita's study area, bears spent 40 percent of their time there eating avalanche-lily roots and other early-blooming plants.

Another biologist, Rick Mace of the Montana Department of Fish and Wildlife, came to a similar conclusion. While avalanche tracks comprised just five percent of his study area, grizzlies spent 60 percent of their time there. Mace found that the bears were attracted to the chutes not just for food; females went to the same areas year after year to breed. The sows simply hung out until the males showed up.

Avalanche chutes and landslide tracks are now viewed with such importance that the British Columbia Ministry of Forests has created buffer zones around them to prevent logging or other manmade disturbances that could interfere with animals' foraging and mating in the open areas. Long seen as only terrifying and destructive, landslides and avalanches are now seen as essential.