Chickadees, despite cute appearance, can hang tough in cold weather
If eagles are noble, owls are wise and doves are peaceful, the chickadee is most often called “cute.”
With its jaunty black cap, large round head atop a tiny body, and quick, curious personalities, the stereotype seems to fit. But beneath the chickadee’s cute exterior, there lies a tough-as-nails survivor. In the wintertime, a chickadee’s day is a race to find enough fuel to power it through the cold dark night. Like a tiny feathered furnace, it must stay lit if it wants to see sunrise.
Unlike many other small birds that either migrate south or to lower elevation in the winter, many of Grand Mesa’s Black-capped and Mountain chickadees stay put. It is a combination of strategic behavior and impressive physiological feats that allow them to brave the extreme cold at high altitude. At the end of the first week of 2017 for instance, nighttime lows on Grand Mesa reached minus-20 in places.
So how does this little songbird stay alive?
You don’t have to remember the high school biology lesson on surface area to volume ratio to know intuitively that, in general, small things get cold faster than large things. If you put an orange and a grape in your freezer, you’d expect the grape to freeze solid first. Many animals that live in cold habitats are larger than their warm weather cousins for this reason — large bodies are better at conserving heat.
But chickadees are tiny, smaller even than they seem to the casual observer. The average chickadee weighs just about 12 grams or the weight of two quarters. Most of what you see is fluff. Beneath their feathers, the chickadee’s body is shockingly small. But it’s those feathers that are their first line of defense against the cold. The chickadee’s winter plumage is much denser and provides more insulation than that of a typical songbird.
When temperatures plummet at night, chickadees do not huddle together for warmth or snuggle in a downy nest. Each bird sleeps alone, often in a tiny crevice that they’ve excavated in a rotten aspen or birch. A small, but sheltered, bedroom for one.
If a cabin is available, chickadees may sometimes take advantage of a man-made cranny under the eaves. This odd roosting behavior was not scientifically documented until around 2000, when Susan Sharbaugh, a researcher at the University of Alaska Fairbanks, put tiny radio transmitters on chickadees and tromped around in frigid winter nights to find their hidey-holes.
Even with their extra-warm feathers and a cozy nook to curl up in, a chickadee has to budget its energy carefully during the night. One way it saves energy is by turning down its body’s thermostat.
During winter nights, chickadees go into a state of controlled hypothermia, dropping their body temperature by 12-15 degrees. If a our body temperature were to drop by 15 degrees, we would be in a state of severe hypothermia and in danger of cardiac arrest. But chickadees do this nightly during the winter and are able to rev up their metabolism and body temperatures in the morning to get to work finding food.
Even with these heat-saving measures, chickadees require an enormous amount of food to make it through a 24-hour period in the winter. They spend the majority of their daylight hours looking for meals. Although chickadees will eat seeds and berries during the winter, protein and fat are most prized. The majority of their winter diet is insect pupae and eggs that they find by scouring tree bark, twigs and needles.
Chickadees will even eat fat off carcasses of dead mammals like elk or porcupines. These busy birds are able to put on up to 8 percent of their body weight in fat in a single day. That would be equivalent to a 150-pound human eating enough in one day to gain 12 pounds of fat. They may burn off all of this fat in a single night just keeping themselves warm(ish).
So the next time you bundle up and visit Grand Mesa, take a moment to appreciate the chickadee.
These tiny dynamos are masters of winter survival. And before you head down the mountain for your hot cocoa and cozy bed, wish them luck. They have a long, cold night ahead of them.