How chickadees survive bitter-cold winters
I appreciate Minnesota's four seasons, including our winters. We are a hardy lot, we Minnesotans, and we're among some of the healthiest people in the nation. I liken our hardiness to the tenacity of our feathered friends that forgo warmer climes for our coldest months. The black-capped chickadee is one such bird.
Black-capped chickadees, a common year-around bird seen on our backyard feeders and throughout Minnesota, are, despite their small size, among the hardiest of the hardy. Have you ever wondered how such a small creature can survive in such a harsh environment?
Why tiny birds like chickadees and other diminutive resident winter birds such as nuthatches and downy woodpeckers don't they freeze to death is remarkable. Yet, the teeny chickadee and others like it are well equipped for survival and they do so with a seemingly happy-go-lucky nature and grace. In fact, chickadees appear to relish winter and embrace it with fervor.
The chickadee is an extraordinary bird. Through time, evolution and natural selection, these small bundles of feathers have proven that where size is lacking, energy and ambition (along with good physiology!) are equal substitutes.
A chickadee's feet and legs are featherless, yet they go about their daily activities unaffected. Try as we might, none of us would last long walking around barefooted in the snow and cold. Chickadees and other birds can do so, however, because of the way blood is circulated throughout their legs and feet.
Physiologists call it "countercurrent heat exchange." In layman's terms, it is just a unique way that blood is circulated in their bodies, specifically within the legs and feet. The warm blood from the body that enters the legs is in close proximity to the blood returning to the body from the legs. This system allows for the colder returning blood to be warmed by the entering warmer blood. Thus, the chickadee's legs and feet stay relatively warm in spite of the outside air temperature!
The feathers on chickadees' bodies do keep them comfy and warm, too. But there is more to the story. The bird adapts to what Mother Nature dishes out by modifying its behavior as well. Chickadees often seek out shelters when the weather takes a turn for the worse. For instance, finding refuge on the downwind side of a tree, inside a birdhouse or tree cavity, or even by huddling close to each other to take advantage of body heat.
The chickadee's physiology also plays a role. To survive bitter cold nights, they have the ability to decrease their body temperature, thus their metabolic rate (other birds do this, too, including hummingbirds in the summertime).
It's sort of like a mini-hibernation. Called torpor, this enables the chickadee to live through cold nights without expending valuable excess energy. Keeping warm is hard work and chickadees solve this problem by "shutting down" during extreme weather conditions.
The chickadee is also a wise forager. They know exactly what high-energy foods to eat. These are such things as conifer seeds, animal fat (suet), and sunflower seeds. And have you ever noticed that the bird never seems to sit at your feeder for very long before flying off with a seed? This is by no accident.
Next time, watch what the bird does with that seed as it flies away with it clenched tightly in its beak. Often, instead of immediately feeding on it, chickadees hide their seeds. Called "caching" the chickadee does this innately, guaranteeing itself a source of food during leaner times (like when we forget to put out the seed or when a severe winter storm comes along).
Their hiding spots tend to be underneath tree bark and inside fissures of trees. Many other birds cache foodstuffs for later consumption, too, including nuthatches, jays, and woodpeckers.
Yes, the adorable little black-capped chickadee that sports a black cap and black bib is a familiar and welcome sight during our long winters. A pleasant and social bird, its bold antics and docile nature makes the chickadee a favorite of all us, as we get out and enjoy the great outdoors.