During the fall migration and winter, chickadees often flock together in flocks of 8–10 birds. Each of the birds in a flock has a rank; while highly ranked birds will remain on the flock's territory for breeding, lower-ranked birds must find new breeding territory. Many other species of birds, including
titmice,
nuthatches, and
warblers can often be found foraging in these flocks. Mixed flocks occur about 50% of the time.
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. Carolina chickadees actively defend individual spaces of 2–5 ft (0.6–1.5 m) apart; if another bird encroaches on these spaces, the dominant bird may make gargle calls. At feeders, these birds will usually take a seed and fly to a branch isolated from other birds to eat it. These birds usually sleep in cavities, though they may sleep in branches. Different members of a flock will sleep in the same cavity from night to night. While females usually sleep in the nest cavity, males will normally sleep on a nearby branch. == Breeding ==