For the Birds Radio Program: Redpolls
Today Laura Erickson talks about the hardiest songbird in the world. 4:05
One of the most abundant birds in the Lake Superior area right now is the Common Redpoll. Flocks of these little finches, somewhat closely related to the Pine Siskin and the goldfinch, zip above Tommy and me every morning when we’re walking to the school bus stop. Some of the flocks alight in my neighbor’s birch trees while most keep going. Even the ones that rest in the branches take just a few birch seeds before moving on, all atwitter as they swirl about through the frigid autumn air.
Redpoll migration is beautifully optimistic–an affirmation of faith that somewhere else the earth is even warmer and more bountiful than it is right here. Chickadees seem equally optimistic as they stay put, trusting that winter can’t possibly be too unpleasant or hard to endure. But some, like Great Homed Owls, hunker down seemingly not out of optimism but out of gloomy despair–to them, conditions would be just as lousy no matter where they went, so they might as well conserve energy and stick it out here.
Redpolls travel throughout the northern reaches of Europe and Asia as well as America. Last week, when the Raptor Research Foundation met in Duluth, ornithologists from Sweden, Norway, Germany, and Finland recognized our little redpolls as the same species that zips through their birch forests. We humans spoke different languages, but the redpolls twittered to all of us in the same jolly tongue.
No matter where they are, redpolls depend on birch, alder, and willow. Their flocks move restlessly through the northern forest in search of seeds fluttering in the breeze. During times of abundance in the far north, females build their nests in spruces, willows, or alders, just 3-6 feet off the ground. They construct the nest with twigs, rootlets, grasses, and mosses, and line it with a thick blanket of warm ptarmigan feathers or lemming fur. Unlike most songbirds, who feed their babies insects or other high-protein animal food, redpolls and other true finches feed their nestlings regurgitated seeds, so even during frigid Aprils way north of us, redpolls can provide plenty of food for their young as long as birch trees are healthy and laden with seeds. Redpolls are gregarious, and, again unlike most songbirds, aren’t particularly territorial, even during nest building. Some pairs nest only a few feet apart, and males seem to sing their junco-like trill not out of belligerance to one another but simply for the joy of singing.
Through the entire year, redpolls wander about the far north, but they sometimes retreat to our latitudes in winter, especially when food is scarce up north. When they can find enough food in winter way up at the top of Canada, they have no trouble surviving the frigid temperatures. To ensure having enough fuel to stoke their metabolic furnaces during endless Arctic nights, they have two special adaptations: a huge numbers of pouches in their esophagus, and eyes with extra rod cells in the retina. This way they can pig out in early evening, after it’s too dark for other songbirds, stuffing those pouches full so throughout the night they can pop seeds into their stomachs without even waking up, digesting and converting food to energy enough for shivering, heating up their muscles and maintaining their body temperature at over 100 degrees. Redpolls can survive temperatures of 67 below zero Centigrade, which translates to 89 below zero Fahrenheit! Good birds really do come in small packages.