by Lincoln Larson
March 10, 2004
Page 2 : Studying the Chilkoot Bears
The Chilkoot River flows about one mile out of Chilkoot Lake and into Lutak Sound, 10 miles north of Haines, Alaska. Every year, four different species of salmon (pink, sockeye, chum and coho) return to the river to spawn. The largest run occurs in September, when over 100,000 pinks and sockeyes (see note below) enter the icy waters to breed. The abundance of salmon attracts many predators to the Chilkoot each fall, including bald eagles and grizzly bears. Hundreds of fishermen and tourists also follow the salmon upstream to capitalize on the extraordinary angling and wildlife-viewing opportunities. This unique situation, a wild Alaskan River with easy road access, raises multiple conservation issues centered on the preservation of Chilkoot’s grizzly bears.
Taking advantage of the ideal setting, the Brown Bear Project focuses on bear foraging ecology and habitat use patterns in relation to the river’s human activity. For two months beginning in mid-August, the research team observed and recorded bear and human behavior along the river corridor. We were stationed at designated points along the river for three-hour shifts at sunrise and sunset (mixed with the occasional midday observation). Though spectators avoided the river on cold, rainy days, adverse weather conditions did not deter the bears or the researchers. We logged many hours huddled in freezing rain, inspired by the rapture of field biology and our majestic surroundings. The observation posts were concealed and did not obstruct bear access routes to the river. As a result, both tourists and bruins were rarely aware of our presence. Using video cameras, binoculars, and tape recorders, we documented human and bear activity throughout the three-hour periods.
From August to October, we viewed 16 different bears (not counting cubs) foraging along the Chilkoot River. Each of these bears was either an adult female (some with litters of up to four cubs) or a subadult (age 2-3 years). The large males presumably stayed deeper in the mountains, farther from the threats posed by hunters and civilization.
During the project, I became very familiar with all the individual bears and their idiosyncrasies. The grizzlies displayed a variety of different fishing techniques. While many of the subadults ran, jumped, and futilely flailed at fish in the swiftly moving water, the older bears had clearly refined their skills. One mother preferred snorkeling for salmon, another opted to wait patiently before plunging on unfortunate passersby, and another had mastered a herding technique, chasing fish into pools with no outlets. The cubs enthusiastically attempted to imitate their mothers’ tactics, but experienced little success. They often left the water and frolicked on the riverbanks, anxiously awaiting the delivery of their next meal.
As the season progressed, the bears began to consume fish carcasses at a higher rate. Live fish offer a richer energy content but, with hibernation looming, bears desperate to pack on the pounds seemed to prefer quantity instead of quality. Individual bears developed certain routines that made their spatial and temporal habitat use patterns very predictable. One adult female emerged from the same spot in the forest at exactly the same time (virtually down to the minute) for five consecutive days, constantly fishing the same segment of the river. With many bears in a relatively small area (up to seven bears were sometimes visible along a 100 meter stretch of river), confrontations and chases between grizzlies unwilling to share fishing spots often occurred. Sows with cubs dominated the river’s feeding hierarchy, and smaller subadults were frequently forced to retreat. All the bears faced one common obstacle, however: human disturbances.
NOTE: Fish counts are conducted at the Weir, a man-made structure composed of a series of closely-spaced bars designed to block fish movement upstream while permitting the free flow of water. A few bars are lifted several times a day, creating a small opening through which fish can pass. Fish & Game Officials count the salmon as they swim by. After spawning, the salmon die and their bodies float downstream. Bears often congregate at the Weir early in the morning to pick the fish carcasses off the bars.
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