The Cornell Lab of Ornithology: “There’s something tranquil about watching birds coexist at your backyard feeder, pecking away in their quirky abandon. That is, until the local Blue Jay arrives, flushing all your daintier songbirds out in a raucous flurry. It might seem like just plain bullying, but there’s more going on than meets the eye in the fast-moving (and frankly addicting) world of bird-feeder drama. Setting out a limited food resource (like a feeder full of seeds) in a time of scarcity (like winter) naturally brings birds into conflict. Just beyond your kitchen windowpane, your backyard feeder is creating the perfect stage to glimpse the inner workings of birds’ social lives—what behavioral ecologists call “dominance hierarchies.” Birds at feeders are like members of a not-so-secret fight club, and the rulebook is in the dominance hierarchy. For a chance to eat in the safety of a flock, they must constantly appease, avoid, or consequently get walloped by more dominant birds. Scientists have spent decades working out the dominance hierarchies among just two or three species. But now, with the help of thousands of citizen scientists, a team of researchers has pieced together a hierarchy that ranks the feeder-fight-club performance of 136 North American bird species.