Black-capped chickadees are omnivorous and have a varied diet that changes with the season .
In summer, their diet primarily consists of insects, especially caterpillars, spiders, and larvae . They also eat small portions of carrion, such as dead mammals .
In winter, the diet includes about half seeds, berries, and other plant matter and half animal food (insects, spiders, suet, and sometimes fat and bits of meat from frozen carcasses) .
At bird feeders, they take sunflower seeds, peanuts, suet, peanut butter, and mealworms .