True to their names, these chickadees have a black cap on their head with a black bib (throat) and white cheeks. They have a gray back and wings with buffy undersides that fade to white on the chest.

Small, stocky birds with short, rounded wings, black-capped chickadees are about 4.5 to 6 inches long (12 to 15 centimeters) with a wingspan of 6 to 8 inches (15 to 21 centimeters). 

Chickadees like open wood and deciduous forests. They thrive in backyards, cottonwood groves and willow thickets. In harsh winter weather, small flocks of black-capped chickadees are sometimes seen in dense pine forests.

Black-capped chickadees can be found across North America, ranging from Alaska through eastern Canada, and spreading southward into the northern parts of the United States. The southern border of their range is slowly creeping north as the climate warms. 

Most chickadees live about two to three years. The oldest chickadee on record was over 11.5 years.

Black-capped chickadees produce a dazzling array of calls. Adults can make as many as 16 different calls, all with different meanings. The call for which they are named in English — "chick-a-dee-dee-dee" — is far more complex than it sounds, with information encoded in each note. Generally the more “dees” that ring out, the greater the threat a predator poses. They also sing a highly recognizable "fee-bee" song. They sing more in the spring than in any other time of year.

Other species of songbirds, especially migrants moving through an area, tend to tag along with chickadee flocks. They listen for the chickadee feeding calls to find food and for chickadee alarm calls to keep them safe.

Chickadees love bird feeders, especially ones with sunflower seeds, suet and peanuts. However, more than half of their food throughout the year consists of insects, spiders, caterpillars, larvae and insect eggs. They have even been known to scavenge on dead deer, skunks and fish. They also eat vegetation, including berries and seeds.

Chickadees hide huge amounts of food for the winter months—in the fall they can store up to 1,000 seeds a day or 80,000 seeds a season, jamming them anywhere they can fit. To keep track of all these seeds, they can replace old neurons with new ones, overwriting old memories with new ones. A chickadee’s hippocampus—the part of its brain responsible for spatial memory—is larger in chickadees that live in places with colder, harsher weather. The hippocampus actually shrinks in the spring when food is easily available and grows again when it’s time to survive the winter.

Chickadees are diurnal, sleeping at night and active during the day. They get up with the first light of dawn after spending their nights sleeping in thick branches or tree cavities with their beak tucked under their wing. They usually sleep alone, though sometimes they will sleep clumped together for warmth. On the coldest nights, they can decrease their body temperature from its normal 107.6 degrees Fahrenheit to 82 degrees Fahrenheit to conserve energy. Very few other birds can replicate this feat. 

Chickadees are social creatures that like to live in flocks of up to 12 birds. Males and females have separate social structures, and the highest-ranking females usually mate with the highest-ranking males. Higher-ranking chickadees tend to have bigger territories, bulkier bodies, higher singing rates and greater reproductive success. Subordinate chickadees tend to forage in the outermost parts of trees, making them most vulnerable to predators, and are braver about approaching or exploring new situations. 

Black-capped chickadees appear to be monogamous. Scientists aren’t yet sure if they mate for life. The male does not display to the female before mating, though he will fly after her. The pair works together to dig out a nest hollow in a dead tree, snag, a rotting stump or a nest box. They can also nest in abandoned downy woodpecker nest holes, and they rarely use the same nest site from one year to another. The mother uses moss and other coarse vegetation to build the nest, which she lines with soft material including fur. Females lay one to 13 eggs which hatch after 12-13 days. Nestlings fledge after 12-16 days.

The mother lays a clutch of between one and 13 white speckled eggs, though typically she lays between six and eight. The mother sits on the eggs for 12 to 13 days until they hatch, while the father brings her food. The chicks stay in the nest for 14 to 18 days after hatching. The family then leaves the nest but will stay together as a group until the young chickadees are five to six weeks old.

Parents feed their nestlings mostly caterpillars and spiders. Spiders provide taurine, a nutrient that is important for chickadee brain formation.

Like many birds, black-capped chickadees are vulnerable to predation, habitat loss and ecosystem degradation. However, the proliferation of backyard feeders and nest boxes have helped bolster chickadee populations.