![]() That means they’ve got to do a lot of foraging every day to replace that energy. But even with an insulating layer of feathers, small birds have a large surface area compared to their body size ( click here for an explanation), so they must burn energy all night long on cold nights. If they did, they’d have a hard time flying and might be easy prey to all kinds of predators, including other birds like the sharp-shinned hawk ( Accipiter striatus). Mixed-species flocks are often studied by biologists in what’s called “the small bird in winter paradigm.” The question is “How does a tiny bird like a chickadee or a sparrow live through the winter in places like Ohio?” They can’t just fatten up like many mammals do in preparation for winter. ![]() In Ohio, you’d be likely to see the black-capped chickadee ( Poecile atricapillus) or the tufted titmouse ( Baeolophus bicolor). The parids are birds in the family Paridae, which includes tits, titmice and chickadees. More Information: Most mixed-species flocks in North America have one or more “parid” species as leaders. In that sense, the leaders and followers “get along well.” It’s possible that the leaders don’t lose much by having the followers, maybe gain a little, and would expend too much energy trying to lose their followers. The benefits fall mostly to “follower” species, however, and it’s less clear why “leader” species put up with the followers. These benefits are not mutually exclusive, and research suggests that in many cases both benefits are present. There are two theories about why birds do this: to improve foraging or to reduce the risk of predation. The Short Answer: In the temperate zone of North America, many smaller birds form mixed-species flocks in winter. But they have arrived together daily for a couple of months. A couple of times a day, the area around my bird feeder is visited by a flock of sparrows that also includes 4-5 female and 3 male cardinals.
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