Birder’s Notebook: Black-capped Chickadees – Cheery, chatty winter neighbors

Every fall my husband and I look forward to the arrival of our wintertime neighbors at Banner Creek – a small flock of black-capped chickadees that keeps us company during short, cold winter days with their lively antics and cheery song. These busy little black-capped birds flit nonstop through the willows pausing briefly at our feeder, often keeping track of each other with their uplifting and distinctive chick-a-dee-deedee song.

The black-capped chickadee is one of seven chickadee species occurring in North America and one of four found in Alaska. They range from Anaktuvuk Pass to New Mexico and are at the westernmost edge of their range on the Seward Peninsula.

Black-capped chickadees are year-round residents and breeders in forested areas of the Seward Peninsula. In most parts of their range, they typically spend their entire lives within the same few square acres of habitat.

However, in the far north some move beyond the forests where they breed into tall shrub habitats for the winter. This behavior apparently explains the regular arrival in the fall of black-capped chickadees at Banner Creek and other shrubby areas near Nome and beyond.

These tiny birds are uniquely adapted to thrive year-round in the far north and survive the coldest Arctic temperatures. Research has found that black-capped chickadees of the north are 25 percent larger than those living in southern regions and able to store more body fat which provides both insulation and fuel for staying warm.

During the winter they have denser plumage than other songbirds of their size which, when fluffed up, provides essential insulation to withstand long subzero nights.

Dr. Susan Sharbaugh, a researcher at the Institute of Arctic Biology in Fairbanks, has studied black-capped chickadees for many years in the Fairbanks area and made fascinating discoveries about their cold weather adaptations.

Sharbaugh found that the birds gorge themselves on frozen insects and seeds throughout the daylight hours, gaining 10 percent of their body weight in fat each day.

Using tiny transmitters, Sharbaugh tracked the chickadees to their nighttime roosts and found they cram themselves into nooks and crannies, often under the bark of birch trees, where they fluff up their feathers and drop their body temperature by 18° Fahrenheit. Their metabolic rate slows to conserve energy and they burn fat all night while shivering to generate heat.

For a bird as small as a chickadee, finding a snug roost is just as important to survival as finding food, according to Sharbaugh. All the roosts she found in the Fairbanks area were in birch trees.

I would love to know where they roost here, where there are no trees large enough to provide cozy sanctuaries under the bark or in woodpecker holes.

Unlike some other songbirds that roost in a huddle for warmth, feisty little chickadees roost alone.

Besides the chickadee’s physiological adaptations, they have evolved a unique feeding behavior that is also key to surviving winter in the far north. When food is abundant in late summer and fall or at a feeder, they cache seeds, insects and other foods throughout their territory. They may stash hundreds of seeds a day in crevices, holes or under bark for later retrieval when food is scarce.

Remarkably, they remember not just where they put the food, but which caches they have already retrieved. Research has found that in the fall there is a 30 percent increase in brain cells in the chickadee’s hippocampus, the part of the brain responsible for spatial memory. The increase in brain cells is greatest in northern populations, where caching behavior is most critical to survival.

The little flock of four, sometimes five, black-capped chickadees that entertains us at Banner Creek comes to our feeder for shelled sunflower seeds and suet at the first hint of light each morning and again as dusk descends. They visit the feeder periodically throughout the day, sometimes eating seeds at the feeder or in nearby willows, but most often they fly off in every direction carrying a seed to cache.

Except when eating a sunflower seed which takes a little work, or pecking fat from the suet feeder, these active little birds are in near constant motion, flitting agilely from branch to branch through the willows, often hanging upside down, gleaning their natural winter foods of insect eggs and larvae from twigs and bark.

During summer months, chickadees eat caterpillars, beetles, moths after discarding the wings, other insects, spiders, seeds and berries. Chickadees also feed on fat scavenged from animal carcasses.

Black-capped chickadees form permanent pair bonds. Unmated birds typically pair up in the fall or when flocked up over the winter. As spring approaches, the flock separates and pairs establish or return to a nesting territory which both birds defend.

It is hard to imagine chickadees using their small bills to excavate a nest cavity in the trunk of a tree, but the chickadee couple tackles that task together. They seldom reuse an old cavity but may further excavate a natural crevice in a tree.

When the cavity is complete, the female builds a nest of moss and plant fibers, lined with feathers and animal fur. She lays up to 11 eggs which she alone incubates for 12-13 days. The male only enters the cavity to feed his mate.

Both parents feed the young which fledge from the nest in about 16 days. The parents care for the fledglings for up to four weeks or until they are able to find their own food and are ready to disperse.

In winter black-capped chickadees gather in small flocks that typically include pairs and unrelated juveniles. They establish a dominance hierarchy with males and older birds dominating females and younger birds.

The little flock of chickadees at Banner Creek initially engaged in more chasing, fleeing and aggressive posturing than they do now that the pecking order is apparently established. However, all the chickadees are subordinate to the other member of this little flock of birds: A downy woodpecker that swoops in to the feeder and chases them all.

Stay tuned to read about him next week.

CACHING SEEDS – A black-capped chickadee about to take off with a shelled sunflower seed to cache it for safe keeping for a hungry day. Studies have found that cached food is most often retrieved by the chickadee that stashed it and seldom is taken by other birds or animals.

INQUISITIVE AND SOCIABLE— One of the charms of black-capped chickadees is their inquisitive behavior. They quickly become habituated to people and often land on me or my camera when I sit quietly near our feeder. Here one is flying in to check out what Pete Rob is up to as he scatters seed on the feeder platform.

FORAGING – Even when bird seed is available, chickadees spend most of their time foraging for their natural foods. This black-capped chickadee was picking insect pupae, which you can see to the right of the bird, off the bark of a willow on the edge of the Nome River.