Birds at Rest: The Behavior and Ecology of Avian Sleep

In this charming study, Pasquier (Birds in Winter), an ornithologist at the American Museum of Natural History, uses sleep as a lens through which to examine the ecology and behavior of birds. He explains that birds, like humans, need sleep to consolidate learning and memory, citing studies that found songbirds practice their tunes by moving their laryngeal muscles as if singing while they slumber. Picking places to roost often involves trade-offs, Pasquier contends, noting that American robins will sleep on the outer branches of fir trees because the needles provide more concealment than closer to the trunk, where there’s more protection from wind. Positing that roosting habits reveal species’ social rituals and organization, Pasquier discusses how African black ducks spend their twilight hours congregating in groups to find mates with whom to sleep, and how red-bill choughs doze in communal roosts where birds too young to mate are “socially segregated according to their age and breeding prospects” from more mature birds. Pasquier packs in a bounty of surprising trivia (many birds have the capacity to rest only half their brain while the other half remains awake, enabling common swifts, frigate birds, and other species to sleep in the air), and La Farge’s dreamy black-and-white pencil drawings are an added treat. Birders will be entranced. Illus. (Feb.)