Black-capped Chickadee
| Scientific Name | Poecile atricapillus |
| Survival Strategy | Active All Winter |
| Conservation status | Least Concern |
Spring
Black-capped chickadees are cavity nesters. In early spring, the birds select a rotted tree branch or knothole as a starting point and excavate the space to their liking. They do not reuse the same cavity the following year. The female builds the nest in late spring and deposits eggs sometime between May through early July.
Summer
Young chickadees fledge after about 16 days and stay with their parents for three to four weeks.
Fall
With parental duties completed for the year, chickadees spend their time caching food for the winter. Caching food serves the same purpose as people canning their garden crops to use all winter.
Winter
Chickadees form flocks of 5 to 10 individuals, often including other winter residents such as nuthatches and woodpeckers. A larger group means more eyes and ears are on the lookout for predators.
Behavior
Cashing Food and Brain Size
Chickadees will cache food throughout their territory for the winter. They hide seeds, small berries, and insects in knotholes, under bark, or tucked into a patch of lichen, with each item is stored in a different spot. The chickadee’s hippocampus, the part of the brain responsible for spatial memory, increases in size by up to 30% during fall food caching. By spring, the hippocampus returns to its pre-autumn size
Roosting
On cold winter nights, chickadees will roost alone in dense conifers or in tiny cavities in a tree to wait out the severe cold.
Physiology
Torpor
If the cold is extreme, chickadees may go into torpor at night, where they become unconscious and enter a state of hypothermia. Their metabolism slows down, and their body temperature drops by ten degrees Celsius (18°F) to conserve the body fat used as an energy source to survive the night.
Sit Tight
When a chickadee (or most other perching birds) sits down on a branch, flexor tendons in its foot tighten. The pull of the tendons forces the toes to lock around the perch. As long as the bird is sitting, it can’t fall off a branch even if it is unconscious.
Shivering
Each winter morning, chickadees will shiver until their body temperature returns to normal. Unlike humans, birds do not shake when they shiver; instead, they rapidly contract opposing muscle groups. To survive at temperatures below 4.5°C (40°F), these tiny birds must consume enough food to power the shivering that keeps their body temperature at 37.8°C (100°F).
Fat as Fuel
Chickadees have little fat reserves remaining as they become active again on cold winter mornings. They need to find fat-rich food sources to increase their body weight by as much as 10% each day to ensure enough fuel to keep them warm each night. The lard-based suet cakes at backyard feeders can be lifesavers.
Feathers
By fluffing up their feathers (piloerection), a chickadee can reduce heat loss by up to 30%. To get an equivalent increase in insulation for a typical home with 12 inches of insulation (R38), you would need to add 6 inches of insulation (R19). Like most birds, chickadees stay dry by preening oil onto their feathers from their uropygial gland near the base of their tail.
An Inner-ear Weather Forecaster
There is an organ inside a chickadee’s ear, the paratympanic organ, which detects changes in barometric pressure, signaling a shift in the weather. This ability helps explain why birds seem to go on a feeding frenzy before a storm.
Diet
Their winter foods include frozen berries, seeds, and occasionally animal fat from carrion. When the insects and spiders become active from spring through fall, they become the mainstay of the chickadee’s diet.
Lifespan and Mortality
The average lifespan of a black-capped chickadee is about 2.5 years. Winter starvation may be the primary cause of mortality, with more than 25% of the birds not surviving when spring arrives.
Predators
Predators of adult chickadees include sharp-shinned hawks, northern shrikes, and domestic cats. Any carnivore that can enter or reach into a chickadee’s nest cavity is a potential nest predator, including raccoons, gray squirrels, red squirrels, and opossums. House wrens destroy chickadee eggs and kill nestlings to take possession of the nest cavity.
Climate Vulnerability
Carolina chickadees, a less cold-tolerant southern cousin to the black-capped chickadee, are now found farther north than in the past. The black-capped chickadee may be being displaced northward as a result. Ornithologists suspect this change in range is related to warmer winter temperatures.
Never stop learning
Literature: In his essay “65290” from A Sand County Almanac, Aldo Leopold described the impact of winter weather on small birds. He wrote, “I suspect that in the chickadee Sunday school, two mortal sins are taught: thou shalt not venture into windy places in winter, and thou shalt not get wet before a blizzard.”
References
| Foote, J. R., D. J. Mennill, L. M. Ratcliffe, and S. M. Smith (2020). Black-capped Chickadee (Poecile atricapillus), version 1.0. In Birds of the World (A. F. Poole, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.bkcchi.01 |
| Lehigh University. “As Autumn Approaches, This Chickadee’s Brain Begins To Expand; New Nerve Cells Put Fall Foraging On Fast Track.” ScienceDaily. ScienceDaily, 12 September 2003. <www.sciencedaily.com/releases/2003/09/030912072156.htm> |
| Journey North: Chickadees! Surviving and Thriving https://journeynorth.org/tm/spring/FebChicadees.html |
| How Chickadees Weather Winter https://www.nwf.org/en/Magazines/National-Wildlife/2008/Backyard-Birding |
| A Sand County Almanac https://www.aldoleopold.org/about/aldo-leopold/sand-county-almanac/ |
| Odum, Eugene P. “Annual Cycle of the Black-Capped Chickadee: 1.” The Auk, vol. 58, no. 3, American Ornithological Society, 1941, pp. 314–33, https://doi.org/10.2307/4078950. |