Takshanuk Watershed Council counted 1,264 birds from the ground Oct. 24, the highest number tallied this season. That puts the size of this year’s migration right on average with previous counts this time of year. Counts of several thousands of eagles in previous years were made from airplanes, which find a larger number of birds.
Eagles appear to come to the Chilkoot drainage first, then the Klehini, before congregating at the confluence of the Tsirku and Chilkat rivers near 19-21 Mile Haines Highway, a pattern that matches salmon migration timing.
A small amount of research on the origin of eagles arriving here indicates they come from as far away as Oregon and Yakutat. The watershed council is working with eagle biologists to collect more data on origins. Eagle watchers who see eagles with leg bands or wing badges are asked to note the date, color and number of the band or badge and report it to the council at http://www.takshanuk.org.
While eagles are feasting, other animals and are preparing for winter. Some hibernate for long periods while others enter shorter states of torpor to conserve energy. During hibernation, heart rate, respiration rate and body temperature drop.
Ground squirrels can lower body temperature to 32 degrees F. and their energy expenditure to 1/50th of their normal, active rate. Bears and our red squirrels don’t go that far. Researchers who believed bears hibernated deeply crept into dens to get rectal temperatures only to find out that those bears aren’t always sound asleep!
But they did learn that a bear’s body temperature drops from 99 F. to 86 F. This suggests bears were metabolizing 4,000 calories per day, compared to about 2,500 used by an average person. When bulking up for winter, bears metabolize as many as 20,000 calories daily. Hibernating bears don’t eat, urinate or defecate for about six months.
Some animals store food or change their diet during winter. A red squirrel can cache as many as 40,000 Sitka spruce cones. Moose switch from a green diet of leaves and water plants to a brown diet of twigs during winter, with blueberry twigs a favorite.
Animals like the weasel and ptarmigan undergo a complete molt for winter camouflage, replacing each hair or feather with a white one. The snowshoe hare, on the other hand, changes only the tip of each hair. The remainder stays gray.
Many of our birds fly south for winter. Some go a short distance; others, a long way. Arctic terns migrate 11,000 miles. Songbirds go as far as South America or as near as Washington state.
Haines is at the edge of several ecosystems and flyways. For some species, we’re a summer grounds only. For others, we’re winter grounds. And for still others, we’re a year-round home. Some mallards and common mergansers are year-round residents, while others are summer breeders only.
In winter, Steller jays seem to move inland while black-billed magpies move into town. Surf scoters raft up in August and fly south to California and Mexico. Just as they’re leaving, Barrow’s goldeneyes are arriving from summer nesting grounds to form large winter rafts.
The golden-crowned kinglet is a four-inch-long songbird that weighs one-fifth of an ounce. But this tiny forager works tree branches all winter, searching for insect larvae. Many of our small rodents take up residence under the snow, building tunnels and caching grasses.
Call the Takshanuk Watershed Council, 766-3542, or visit the group’s website to add your observations and photos.