For the Birds Radio Program: Chickadee Hierarchies
There’s no way to deny that autumn is really and truly here, with winter in view. With the definite change in season, there’s a definite change in my neighborhood chickadees. Families are split up now, and each baby in a brood goes off and joins a flock different from its siblings’. This is a good strategy for genetically related chickadees to separate so that at winter’s end they won’t end up selecting a sibling for a mate. But it also means that every October, flocks have to work out a whole new social hierarchy.
In one very real sense, chickadee flocks are extremely egalitarian. They accept all manner of birds into their flocks, including warblers, nuthatches, kinglets, vireos, and creepers. Their sociability even extends to humans that they learn to trust won’t kill them if they offer food on hands that weigh many times more than an third-of-an-ounce chickadee.
Chickadees are friendly to one another, too, as long as they keep at arm’s length. And here I don’t mean at wing’s length, but rather the length of a professional basketball player’s arm, or usually even more. Chickadees are the natural world’s premier Norwegian bachelor farmers. They’re sociable—ya sure, you betcha. If you see one chickadee, you can bet your bippy there are other chickadees nearby. But they feel uncomfortable and stressed when other chickadees approach too closely, invading their body space, and for such tiny birds they require a lot of space around their bodies. At nighttime each chickadee sleeps in its own personal cavity—even in the dead of a northern Minnesota winter, they just don’t share body heat. And they never eat shoulder to shoulder at feeders the way finches do. Instead, they each grab a seed and fly off to eat in seclusion. To minimize unpleasant interactions, they don’t come to feeders in random order, either, but in a clearly-defined order dictated by their position in the flock’s hierarchy. It takes days or, sometimes, weeks for each flock to figure out its hierarchy, but once it’s all worked out, squabbling will be at a minimum, and the whole flock can focus on feeding and keeping a lookout for danger. If you want to preserve the image of peaceable birds that never bicker, avert your eyes from your chickadee feeders for a few weeks. But if you’re fascinated by bird behavior and the delicate dance that each chickadee must do to avoid an out-and-out battle in working out who’s on first, this is the time to pay attention.
My chickadees have been squabbling every time they come to the feeder, because as new individual chickadees, strangers from throughout the area, join the flock they have to figure out where they fit. If two chickadees come to the mealworms at the same moment but already know which one is dominant, the lower-ranking bird simply and quietly withdraws and waits its turn. But if one of the birds is new to the flock, it doesn’t accept that its position is at the bottom of the hierarchy and sometimes is willing to fight for a higher position. Of course, even when the stakes are high chickadees aren’t very militant, so they do some tail swishing and funny sidestepping, and only occasionally actually come to blows. When they do, the winner of that altercation invariably ends up higher on the ladder than the loser. Seldom is there a replay—it wastes time and the other birds in the flock grow impatient. So it won’t take long for our backyard chickadees to resolve all their disputes and get back to their peaceable, well-ordered lives. Enjoy the skirmishes while you can, or, if you can’t stand the tension, avert your eyes. Me, I’m averting my eyes from the tension of whether the Cubs are going to win the pennant so right now I’m focusing on my chickadees.