Ever notice that black-capped chickadees look kind of fat in the winter? They’re not: like many birds that brave the cold season here instead of heading south, they’re just fluffing out their feathers. This trick traps a layer of insulating air around their bodies and helps reduce heat loss.
These little birds—they only weigh about as much as a handful of paperclips—spend their days scarfing the seeds and berries that they tucked into food caches in the fall. Along with strong, long legs—longer than other perching birds—chickadees have muscles that allow them to hang upside down to access tricky hiding or foraging spots. At night, black caps go into a state of regulated hypothermia. By dropping their body temperature (in some cases, by as much as 10°C) they can conserve energy.
Chickadees gather in flocks of a dozen or more birds in winter. They warn each other of danger, share food discoveries, and work as a team to guard territories. By March, the birds have breeding on the brain, and flocks break into mating pairs. Listen for the males’ two-note whistle (“fee-bee”).
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