An acrobatic white winged crossbill looks for seeds.
Common redpolls like this can eat around 40% of their body mass daily.
Imagine being a tiny songbird who flies across thousands of miles of boreal forest, facing frigid temperatures and snowstorms, searching for the next crop of birch or spruce seeds. All the while calling joyously to your flock mates as if you didn't have a care in the world.
Look at your birdfeeder or spruce trees, and you'll likely see a flock of songbirds - common redpolls, pine siskins, or white-winged crossbills. In some winters, you may see an unexpectedly large number of them.
Redpolls, siskins and crossbills are all seed specialists who follow spruce and birch crops throughout the year. They are also known for sporadic, erratic and irruptive movements that deviate from the normal and occur in sudden, unpredictable or irregular intervals.
Seed crops are highly variable in distribution and abundance from year to year and may fail in some years. As these songbirds search for seeds, they may travel hundreds or thousands of miles. The time, direction and distance of travel differ each year. Fortunately, these resilient birds are flexible and easily adjust their movements.
Each of these species travels in large flocks and sometimes will occasionally form mixed flocks with each other. Flocks of several dozen to hundreds of birds are common. When they follow a seed crop to urban areas, it can seem like a sudden invasion of innumerable birds calling, flitting back and forth, and clearing out your seed feeders in minutes.
As scientists study these birds to learn more about their movements, they have found that some birds have changed their pattern of following the birch and spruce seed crops and will delay or shorten their journeys to feast on the seeds we provide.
And feast they do. To make it through a freezing night, a redpoll can eat the equivalent of a 150-pound human eating 62 pounds of food a day. Redpolls can eat around 40% of their body mass daily, and crossbills can eat over 3,000 spruce seeds daily.
In addition to being intrepid travelers, redpolls, siskins and crossbills are well adapted for the cold subarctic climates. These tiny birds can survive temperatures of -58 degrees Fahrenheit by being well-insulated, putting on extra fat during the winter, and roosting with others during the night for warmth. Redpolls will even burrow into a snow tunnel for a cozy night's sleep. Redpolls and siskins store seeds in their expandable esophagus so they have food to eat during the cold nights.
When you see a flock of these undaunted songbirds, think about how their fluid, dynamic and flexible way of life makes it possible for them to survive Alaska's winters and for us to enjoy their gregarious and exuberant natures as they flit through the trees, talking to each other and braving winter's elements.
Since the beginning of the year, Bird Treatment and Learning Center has taken in 19 redpolls and crossbills, most of whom have been injured when they collided with windows. Find out how you can prevent birds from striking your window at https://abcbirds.org/solutions/prevent-home-collisions/.
Lisa Pajot is an ornithologist and Bird Treatment and Learning Center volunteer.
