We know a lot about the remarkable Chickadee

It’s barely dawn and the temperature hovers at 30 below zero. But there at your bird feeder is the remarkable little Black-capped Chickadee. It weighs in at only about 10 grams, or less than two quarters, yet it is one of the most successful survivors of our long, cold and dark Alaska winters.

The Black-capped Chickadee is an extremely common and tame bird, and most spend their entire life within about half-mile of their birthplace. This makes it an easy bird to study, so there is a wealth of information on how they make it through winters that drive other birds (and indeed many Alaskans) to head south.

We are all aware that the chickadee readily visits bird feeders. This in itself is a survival trait. In urban areas where natural food may be harder to find, the black oil sunflower seed and suet we feed provide valuable fat calories for the chickadee. In nature, the chickadee eats a variety of foods in the summer: seed, insects and fruit. In the winter, insects and fruit are unavailable and the seed crop has diminished.

To fuel the need for energy, chickadees use their tough, conical beaks to break into conifer seeds and collect tiny birch catkins. Once a carnivore has torn into the carcass of an animal, the chickadee, as well as other birds, will take advantage of the exposed fat for food energy. The extra fat consumed in the winter allows them to survive long hours without eating and gives the bird an insulating layer against the cold. Small birds, like the chickadee, require more food relative to their size than larger birds, due to their greater surface area compared to body size. They need to forage nearly continuously during the short daylight hours.

Don’t be concerned if you miss a day filling your feeders, however, as studies have shown that even where feeders are readily available, the chickadee only uses them for about 20 percent of its food. And this resourceful bird has even more survival tricks in its tool kit.

Feathers are the insulating layer for a bird, just as a down coat warms us. In winter, a Black-capped Chickadee will grow additional feathers, up to as many as 10,000. The added warmth is further increased by fluffing these feathers to create an air blanket against the skin, where the temperature may remain over 70 degrees even when the outside air is well below zero. Notice how big the chickadees look on a very cold day with this fluffy coat. Only a thin layer of feathers separates what could be a temperature difference of over a hundred degrees from the bird’s skin to the air temperature.

What of those tiny, bare feet? Like all other passerines, Black-capped Chickadees do not have insulating feathers on their feet or legs. You will often see them perched squatted down, using their body feathers to warm their feet. In addition they have a unique system of blood vessels in their legs that allows warm arterial blood to pass alongside the cold returning venous blood from the feet, acting like a radiator.

As evening approaches, Black-capped Chickadees will retire to a warm roost. Tight against the trunk of a spruce tree or in a woodpecker hole they will huddle together, using each other’s body heat and proximity to stay warm and minimize heat loss. The temperature in an enclosed roost can reach up to 90 degrees. There are reports of chickadees using nest boxes in the winter for roosting; designs exist for building special roost boxes with the opening on the bottom and perches up high to conserve heat.

To keep its metabolism on high throughout the night, the Black-capped Chickadee will shiver. The special kind of body fat produced when birds eat high-fat foods allows them to maintain this high use of energy up to six to eight hours even at our coldest temperatures. During the coldest nights, the chickadee will go even one step further in conserving energy and enter a state of unconsciousness called torpor. In torpor, the bird lowers its body temperature by about 14 degrees, and its respiration and heart rate slow. This allows the Black-capped Chickadee to use up to 20 percent less energy during the night. As day draws near, he begins to shiver again to bring his internal temperature back up to the normal of 104 degrees.

If you have ever thought of yourself as a superior being, note how the humble chickadee is so much more capable of surviving in the winter than we humans.

In the next article we will explore more birds’ winter survival tricks.

Nancy Wade is a member of the Mat-Su Birders and Alaska WildBird Rehabilitation Center. Send birding questions for her column on birding to alaskaflamingo@yahoo.com.