Black-capped chickadee

Appearance

The black-capped chickadee has a black cap and "bib" with white sides to the face. Its underparts are white with rusty brown on the flanks. Its back is gray and the tail is normally slate gray. This bird has a short dark beak of 8–9.5 mm, short, rounded wings 63.5–67.5 mm, a tarsus of 16–17 mm, and a long tail at 58–63 mm. Its total body length is 12–15 cm, wingspan is 16–21 cm, and body mass is 9–14 g. Sexes look alike, but males are slightly larger and longer than females.

Status

The IUCN classifies the black-capped chickadee as least concern due to its wide distribution and large populations. In Alaska and Washington, and parts of western Canada, black-capped chickadees are among a number of bird species affected by an unknown agent that is causing beak deformities, which may cause stress for affected species by inhibiting feeding ability, mating, and grooming. Black-capped chickadees were the first affected bird species, with reports of the deformity beginning in Alaska in the late 1990s, but more recently the deformity has been observed in close to 30 bird species in the affected areas.

Behavior

It is well known for its ability to lower its body temperature during cold winter nights, its good spatial memory to relocate the caches where it stores food, and its boldness near humans.

Reproduction

The black-capped chickadee nests in a hole in a tree, 1–7 m above ground. The pair either excavates the hole together, or uses a natural cavity, or sometimes an old woodpecker nest. This species will also nest in a nesting box. The nesting season is from late April through June. The nest is built by the female only. It consists of a base of coarse material such as moss or bark strips, and lining of finer material such as mammal hair. Eggs are white with fine dots of reddish brown concentrated at the larger end. On average, eggs are 1.52 cm × 1.22 cm. Clutch size is six to eight eggs. Incubation lasts 11–14 days and is by the female only, which is fed by the male. If an unusual disturbance occurs at the nest entrance, the incubating female may utter an explosive hiss, like that of a snake, a probable adaptation to discourage nest predators.

Hatchlings are altricial, naked with their eyes closed. Nestlings are fed by both sexes, but are brooded by the female only. Young leave the nest 12–16 days after hatching, in great part because the parents start presenting food only outside the nest hole. The young are still fed by the parents for several weeks, but are capable of catching food on their own within a week after leaving the nest.

Black-capped chickadees usually breed only once a year, but second broods are possible if the first one is lost. First breeding is at one year of age. Maximum recorded lifespan is 12 years, but most individuals live only half that long.

Black-capped chickadees are socially monogamous, and males contribute greatly to reproduction. During the laying and incubation periods, males feed their partners extensively. When the nestlings hatch, males are the primary providers, but as the nestlings grow, females become the main caretakers. Females prefer dominant males, and greater reproductive success is closely related to the higher ranking of the male.

Black-capped chickadees may interbreed with Carolina chickadees or mountain chickadees where their ranges overlap. It appears to be more rare, but interbreeding with boreal chickadees has also been documented.

Food

Insects form a large part of their diet in summer. The birds hop along tree branches searching for food, sometimes hanging upside down or hovering; they may make short flights to catch insects in the air. Seeds and berries become more important in winter, though insect eggs and pupae remain on the menu. Black oil sunflower seeds are readily taken from bird feeders. The birds take a seed in their beak and commonly fly from the feeder to a tree, where they proceed to hammer the seed on a branch to open it.

Like many other species in the family Paridae, black-capped chickadees commonly cache food, mostly seeds, but sometimes insects, also. Items are stored singly in various sites such as bark, dead leaves, clusters of conifer needles, or knothole. Memory for the location of caches can last up to 28 days. Within the first 24 hours, the birds can even remember the relative quality of the stored items.

Foraging behaviour in the winter tends to decrease due to the changing weather. Such behaviour is largely influenced by wind and temperature. When wind speeds are higher, black-capped chickadees avoid exposure to such conditions by flying lower where vegetation offers a degree of protection, and when the temperature decreases, they search for food less frequently.