The black-capped chickadee (Poecile atricapillus) is a small, nonmigratory, North American passerine bird that lives in deciduous and mixed forests. It is a member of the Paridae family, also known as tits. It has a distinct black cap on its head, a black bib underneath, and white cheeks. It has a white belly, buff sides, and grey wings, back, and tail. The bird is well known for its vocalizations, including its fee-bee song and its chick-a-dee-dee-dee call, from which it derives its name.
The black-capped chickadee is widely distributed throughout North America, ranging from the northern United States to southern Canada and all the way up to Alaska and Yukon. It feeds primarily on insects and seeds, and is known for its ability to cache food for use during the winter. The hippocampus of the black-capped chickadee grows during the caching season, which is believed to help it better remember its cache locations. The black-capped chickadee is a social bird and forms strict dominance hierarchies within its flock. During the winter, these flocks include other bird species. It has the ability to lower its body temperature during cold winter nights, allowing it to conserve energy.
Black-capped chickadees build nests in tree cavities, with the nesting season starting in late April and lasting until late June. They lay on average 6–8 eggs, which hatch after 11–14 days. Juveniles fledge 12–16 days after hatching.
The population of black-capped chickadees is thought to be increasing, and they are considered a species of least concern by the International Union for Conservation of Nature (IUCN). It is the state bird of both Massachusetts and Maine in the United States, and the provincial bird of New Brunswick in Canada.
Taxonomy
In 1760, French zoologist Mathurin Jacques Brisson included a description of the black-capped chickadee in his book based on a specimen collected in Canada. He used the French name and the Latin Parus Canadensis Atricapillus. Although Brisson gave it Latin names, these do not conform to the binomial system and are not recognized by the International Commission on Zoological Nomenclature. In 1766, Swedish naturalist Carl Linnaeus published the 12th edition of his Systema Naturae, which included 240 species that had been previously described by Brisson. The specific epithet atricapillus is Latin for "black-haired" from (black) and (hair of the head).
Though originally placed in the genus Parus with most other tits, mtDNA cytochrome b sequence data and morphology suggested that separating Poecile more adequately expressed these birds' relationships. The genus Poecile had been introduced by German naturalist Johann Jakob Kaup in 1829, and the American Ornithologists' Union moved the black-capped chickadee into this genus in 1998. Molecular phylogenetic studies have shown that the black-capped chickadee is sister to the mountain chickadee (Poecile gambeli).
The following cladogram shows the relationships between the various chickadee species, a subset of genus Poecile: however, the distinction of the Carolina chickadee remained in question until 2005.
- Poecile atricapillus turneri <small>(Ridgway, 1884)</small>: Found in southern Alaska and northwest Canada and has the palest colouring of all subspecies.
- Poecile atricapillus occidentalis <small>(Baird, 1858)</small>: Ranges from southwest British Columbia to northwest California, and is the smallest in size and darkest in colouring of all subspecies. Males have a wing length of , a tail length of , a bill length of , and a tarsus length of . Females are on average slightly smaller, with a wing length of , a tail length of , a bill length of , and a tarsus length of . Both sexes weigh .
Vocalization
thumb|Black-capped chickadee, Iona Beach Regional Park
The vocalizations of the black-capped chickadee are highly complex, with 16 distinct types of vocalizations being used to convey an array of information. These vocalizations are likely an evolutionary adaptation to their habitat; they live and feed in dense vegetation, and even when the flock is close together, individual birds tend to be out of each other's visual range.
One of the most recognizable sounds produced, particularly by the males, is the two-note fee-bee song. It is a simple, clear whistle of two notes, identical in rhythm, the first roughly a whole-step above the second.
The frequency of their songs typically starts around 400 Hz, and various tones spanning roughly 1 kHz are sung within the song. A decrease of roughly 200 Hz occurs when the first note (fee) is sung, and then another decrease around 400 Hz takes place between the end of fee and the beginning of bee. In spite of these multiple changes in frequency, though, anybody listening to the song only hears a pure, high-frequency tone. This is distinguished from the Carolina chickadee's four-note call fee-bee fee-bay; the lower notes are nearly identical but the higher fee notes are omitted, making the black-capped song like bee bay. The males sing the song only in relative isolation from other chickadees (including their mates). In late summer, some young birds sing only a single note.
Both sexes sometimes make a faint version of the fee-bee song, and this appears to be used when feeding young.
The most familiar call is the chick-a-dee-dee-dee, which gave this bird its name. This simple-sounding call is astonishingly complex. Like other sounds the chickadee produces, it may be heard in multiple variations. The A and B notes are almost identical to one another in both frequency and duration, though black-capped chickadees possess the ability to quickly notice the difference between these two notes. No such similarity is seen between the C and D notes. These species will react when a chickadee makes the alarm call. Red-breasted nuthatch have even been observed reacting more strongly to higher-threat alarm calls, indicating some understanding of their syntax.
Black-capped chickadees make a number of other calls and sounds, such as a gargle noise usually used by males to indicate a threat of attacking another male, often when feeding. This call is also used in sexual contexts. Black-capped chickadees learn the gargle noise soon after birth and continues to develop it through to adulthood. They range from western Alaska, through southern Yukon and throughout the Canadian provinces, from British Columbia in the west to the Maritimes and Newfoundland in the east. The distribution continues into the United States, with its range extending to northern California in the south-west, through northern Nevada and New Mexico, continuing through the midwestern United States to New Jersey. It can also be found in the Appalachian Mountains at higher elevations. They are typically most common at elevations below , 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. 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.
This caching behaviour has led to black-capped chickadees having larger hippocampi compared to other chickadees, who themselves have relatively larger hippocampi compared to other caching birds in the Paridae family. This variation in size also exists within the black-capped chickadee population based on the region they inhabit, with those who live in harsher climates (such as Alaska) having larger hippocampi. However, no variation exists between the sexes. The size of the hippocampus within black-capped chickadees also varies throughout the year, being the largest in October, and the smallest in February. While the exact reason for this seasonal change is unknown, it is believed that the hippocampus grows to allow the chickadee to remember its cache locations, and then shrinks as those caches are used up.
thumb|Black-capped chickadee at a [[Bird feeder|feeder]]
Foraging behaviour in the winter tends to decrease, primarily being affected by lower temperatures and stronger winds. In parts of the black-capped chickadee's range with very cold winters, such as Minnesota, survival rates are affected by access to supplemental food. Chickadees with access to bird feeders in a very cold winter are twice as likely to survive than those without access to this supplemental food; months with severe weather when the temperature drops below for more than five days make the primary difference between the survival rates with and without feeders. In Pennsylvania on the southern edge of their range, with milder winters, monitoring of populations with and without feeders suggests that feeders in milder weather influence movements of chickadees but not their actual survival.
Metabolism
On cold winter nights, these birds can reduce their body temperature by as much as 12°C (from their normal temperature of about 42°C) to conserve energy. Such a capacity for torpor is not very common in birds. Other bird species capable of torpor include the common swift (Apus apus), the common poor-will (Phalaenoptilus nuttallii), the lesser nighthawk (Chordeiles acutipennis), and various species of hummingbirds.
Movement and roosting
During the winter, chickadees often flock together. Many other species of birds – including titmice, nuthatches, and warblers – can often be found foraging in these flocks. Mixed flocks stay together because the chickadees call out whenever they find a good source of food. This calling-out forms cohesion for the group, allowing the other birds to find food more efficiently. Black-capped chickadees sleep in thick vegetation or in cavities, usually singly, though they may occasionally roost clumped together.
Their flight is slightly undulating with rapid wing beats. Flights are typically short bursts of less than with a speed around . They tend to avoid flying through large open areas and will instead be found flying along tree-lines or through forests.
Moult
Chickadees moult once a year, starting in July or August and usually taking two to three months. They do not moult in the spring prior to breeding. The postjuvenal moult at the end of the first summer of life is partial, involving only the body feathers and wing coverts. In subsequent years, the postnuptial moult at the end of each reproductive season is always complete, involving all feathers. Moulting chickadees are not often seen, preferring to remain silent and hidden from view.
The black-capped chickadee nests in tree cavities above ground. Nest sites are typically chosen by females, but excavation of the cavity is done by both sexes. The nest itself is built by the female only and consists of a base of coarse material such as moss or bark strips, and lining of finer material such as mammal hair. The nesting season is from late April through June, with higher-ranking females nesting before lower ranking ones. Eggs are white, with fine reddish brown dots that are concentrated at the larger end. On average, eggs are , and there are usually six to eight eggs. Incubation lasts 11–14 days and is by the female only; the male feeds her during this time.
thumb|right|Black-capped chickadee hatchlings are [[altricial and born without feathers.|alt=Two featherless black-capped chickadee hatchlings next to egg shells]]
Hatchlings are altricial, emerging featherless with their eyes closed. Nestlings are fed by both sexes, but are brooded by the female only (the male brings food to her during brooding, which she passes on to the young). 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. although most live roughly 2.5 years. Interbreeding with boreal chickadees (P. hudsonicus) has also been documented, though it is more rare.
Predators and parasites
Black-capped chickadees are primarily subject to predation by birds of prey, including owls, hawks, and shrikes. Nest-predation also occurs, primarily by raccoons, squirrels, opossums, and snakes.
Like many birds, black-capped chickadees are susceptible to West Nile virus. They are also known to be affected by blood parasites, including those that cause malaria, but particularly high rates of infection have not been detected.
State and provincial bird
thumb|right|A Maine registration plate, with a black-capped chickadee on the left|alt=A vehicle registration plate from Maine, with a black-capped chickadee perched on a pine branch on the left of the plate
The black-capped chickadee is the state bird of Maine and Massachusetts and the provincial bird of New Brunswick. In 2022 the black-capped chickadee was named the official bird of Calgary, Alberta. In 2015 the black-capped chickadee was voted the unofficial bird of Ottawa, Ontario. The bird is prominently featured on the standard Maine vehicle registration plate.
Conservation
The IUCN classifies the black-capped chickadee as least concern due to its wide distribution and large populations. Yearly bird counts such as the Christmas Bird Count indicate that the population is increasing. The total population across its range is estimated to be 43 million mature individuals as of 2025.