On a winter day, a big flock of streaky brown chickadee-size birds swarms my neighbor's feeder. While some are perched on the feeder, most are hopping around on the ground, pecking at the spilled seeds. The yellow feathers on the wings and streaky yellow breast identifies these little finches as pine siskins.
Related to the beautiful goldfinches found in the Lower 48, siskins are northern-adapted cousins, well-suited for life in Alaska and Canada. They don't migrate south for the winter, but they do range widely in search of food. If they have enough to eat, they can endure brutally cold winters in Interior Alaska. Siskins put on significantly more winter fat than their cousins, the redpolls and goldfinches. The siskins metabolic rate is about 40% higher than a "normal" songbird of their size. When temperatures in Interior Alaska plunge to 50 or 60 degrees below zero, these hardy little finches accelerate that already high metabolic rate up to five times normal for several hours. They store extra food in a special throat pouch called a crop, and use this valuable energy source to fuel that high metabolic rate on cold nights.
If nesting siskins are hit with spring weather in the spring, they protect their young. Siskin nests are heavily insulated with a thick layer of plant materials. And in a cold snap a nesting female will incubate her eggs or young hatchlings 24 hours a day while her mate brings her food.