The Social Lives of Birds

In The Social Lives of Birds, evolutionary biologist Joan Strassmann examines what it means for birds of a feather to flock together. Some birds sleep together. Some join the foraging groups of other species. Some are only social during the breeding season, forming nesting colonies in trees, cliffs, and sandbanks. Some are altruistic, helping to rear young that are not their own. Some males perform mating dances together.

Strassmann explains how flocks provide safety in numbers, roosts offer warmth and shelter, and colonies allow for protected breeding. But group behavior is not without its costs-including increased competition, infidelities, tick infestations, and more. Strassmann exposes the conflicts birds face and the many ways in which they resolve these conflicts.

With stories of birds from around the world-from broad-winged hawks that migrate south together in the fall, tree swallows that roost together in the thousands, and tropical anis that nest in communes: The Social Lives of Birds explores the different kinds of bird groups and what to look for when watching them. Above all, it reveals that solitary life, it seems, is not for the birds.