Black-capped Chickadee

The Black-capped Chickadee, (Parus atricapillus), is a small songbird, a passerine bird in the tit family Paridae. Often, it is still placed in the genus Parus with most other tits, but mtDNA cytochrome b sequence data and morphology suggest that separating Poecile more adequately expresses these birds' relationships (Gill et al., 2005). The American Ornithologists' Union has been treating Poecile as distinct genus for some time already.
Adults have a black cap and bib with white sides to the face. Their under parts are white with rusty brown on the flanks; their back is gray. They have a short dark bill, short wings and a long tail.
Their breeding habitat is mixed or deciduous woods in Canada, Alaska and the northern United States. They nest in a hole in a tree; the pair excavates the nest, using a natural cavity or sometimes an old woodpecker nest. They may interbreed with Carolina Chickadees or Mountain Chickadees where their ranges overlap. The Black-capped and Carolina chicadees are virtually impossible to tell apart visually, but they are readily distinguished by call. Their point of overlap is near New Brunswick, New Jersey.They are permanent residents, but sometimes move south within their range in winter. On cold winter nights, these birds reduce their body temperature by up to 10-12 °C to conserve energy.
These 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. Insects form a large part of their diet, especially in summer; seeds and berries become important in winter. They sometimes hammer seeds on a tree or shrub to open them; they also will store seeds for later use. Black-capped Chickadees are known to remember the position of hundreds or more of their food caches for up to a month[citation needed].
During the fall migration and 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. When flocking, Black-capped Chickadees soon establish a rigid social hierarchy.