Insects and spiders, including their eggs and larvae, make up the majority of the boreal chickadee’s diet. It will also take seeds, especially during winter (2) (4). An opportunistic species, the boreal chickadee forages by hopping on twigs and branches, gleaning food off the surface of the tree or probing into crevices in the bark. It will occasionally hover in front of branches, and will hangs upside-down to get at the undersides of branches, cones and needles (2) (4).
The boreal chickadee frequently stores ‘parcels’ of food in storage points, such as in bark crevices, under lichen and between spruce needles (5). This behaviour allows the boreal chickadee to cope with the harsh boreal environment during winter and other periods of food scarcity (2) (4) (5) (6).
The breeding season of the boreal chickadee typically begins around May, when breeding pairs will defend small territories (4) (7). The boreal chickadee nests in cavities in trees, which both the male and female excavate prior to mating. The pair inspects a number of holes and cavities together, although it is usually the female that begins the initial excavation of the chosen cavity (2) (4) (7). The boreal chickadee often enlarges an existing hole in a tree, but it will also use old woodpecker holes, and has been observed using the earth beneath exposed tree roots for nest sites (2) (4). The nest itself is usually lined with a combination of dry moss, pieces of bark, hair, fur, feathers, lichen or ferns (2) (4).
The boreal chickadee produces a clutch of four to nine eggs, which are incubated solely by the female. Incubation generally lasts for around 15 days, during which time the male only enters the cavity to feed the female. Following hatching, the female broods the young for up to 11 days, with both adults contributing to feeding the chicks (2) (7). The young leave the nest at about 18 days, but stay on the breeding territory for another two weeks (4) (7).
Although this species inhabits boreal forest throughout the year, in some parts of its range it may undertake short-distance movements in response to localised food shortages (4).