Birder’s Notebook: Boreal Chickadee––The lesser-known chickadee
Sweet—another winter visitor from the boreal forest has arrived. A boreal chickadee recently joined the little flock of blackcapped chickadees that regularly visits our Banner Creek bird feeder.
Both chickadee species are birds of the spruce forest, but in winter small numbers may move into surrounding willow and alder habitats. While a few black-capped chickadees come regularly to the Nome area in winter, boreal chickadees show up infrequently. Seldom have I seen more than one or two at a time. It is a treat to have this brown-capped sprite in the mix.
Chickadees are such cheery, active birds, but with a feisty streak. There is a noticeable dominance hierarchy if you watch the flock for long. The boreal chickadee seems to be at the bottom of the pecking order, often getting displaced from the feeder and chased through the willows by its black-capped relatives.
The boreal chickadee is one of just a few songbirds that lives yearround in the northern boreal forests of Alaska and Canada, making no regular southerly migration. Their habitat dips south of the Canadian border into only a few of the northernmost states.
Generally, individuals stay throughout the year in their forested breeding areas. Sometimes, perhaps due to food shortages or higher survival of young than usual, some boreal chickadees disperse in fall and winter into alder and willow thickets beyond the spruce forests.
During winter, boreal chickadees form small flocks, most often with only their own kind but sometimes joining mixed flocks of other wintering songbirds. They range each day between feeding sites and return at night to roost alone in a tree cavity or other protected cranny, sometimes beneath a human dwelling or under eaves.
The life history of boreal chickadees has been less studied than that of their more numerous, accessible and widespread blackcapped relatives.
Courtship and pair formation happens sometime during the winter flocking period. Pairs remain together year-round and may mate for life. Winter flocks typically break up in late April and pairs return to their breeding territories or establish new ones.
Boreal chickadees nest in holes in trees. They may use natural cavities or old woodpecker holes. Amazingly, they may even excavate their own nest cavity with their tiny bills, in which case the female does most of the work.
In late May, up to nine eggs are laid in a lined cavity. The female incubates the eggs for 15 days while the male feeds her and defends their territory. Both parents feed the chicks. The young fledge in 18 days and stay with the parents for another two weeks before dispersing.
During the breeding season boreal chickadees eat a high protein diet of spiders, caterpillars, moths, beetles and other insects.
Seeds, berries and fat scavenged from carcasses are a minor part of their summer menu.
In winter, their diet shifts to seeds and dormant insects, insect eggs and pupae. In the spruce forest, spruce seeds are especially important and boreal chickadees can be seen hanging from the cones and pecking to extract seeds.
The chickadees foraging out our window are always busy and in nearly constant motion. They move agilely through the branches, often hanging upside-down, inspecting everything from the trunks to the twigs. They pry into bark with their tiny bills to find hibernating insects, pupae or eggs.
All chickadees cache both insects and seeds for future consumption. Caching is done while clinging to a branch or trunk and seeds are wedged into crevices. Sometimes food is adhered with saliva or web material from spiders or cocoons. The use of spider webs for caching is unique to boreal chickadees.
Caching is critical for a chickadee’s winter survival during times when weather may prevent foraging. Studies have shown chickadees have a remarkable memory for relocating their caches.
The boreal chickadee diet is essentially the same as that of the black-capped chickadee. Where their ranges overlap, the two species forage in different portions of the habitat to reduce competition for food. In general, boreal chickadees prefer the densest parts of the spruce forest while black capped chickadees select more open forest habitat, often mixed with some deciduous trees.
Like black-capped chickadees, boreal chickadees have physiological adaptations to survive harsh winter conditions in the far north. Their plumage is denser and better insulating than that of other small songbirds. They are able to put on up to eight percent of their body weight in fat every day to replenish their reserves and stoke the internal fire for the coming night. At night their metabolic rate slows to conserve energy. They burn fat all night while shivering to generate heat.
During the recent blizzard it was remarkable how the flock of tiny, featherweight chickadees managed to make their daily rounds to our feeder and maneuver with precision in high winds to grab and cache or eat the seeds.
Boreal chickadees are noted for their curiosity and tameness around people, and in my experience in the past that has been true. However, our current visitor is playing hard to get.
After 10 days of attempting to photograph this bird right by my house, the score is boreal chickadee 10, Kate 0.