Although the American Dipper (Cinclus mexicanus) uses a variety of sites on the ground adjacent to streams for nocturnal roosts, I observed nocturnal roosting in a tree by this species, apparently the first reported case for any dipper species. A fledgling spent at least 8 hours between 20:06 and 04:30 MST sleeping 1.5 m high in a black cottonwood tree (Populus trichocarpa), at the tip of a branch overhanging a creek. Use of arboreal roost sites may reduce the probability of predation on fledgling dippers while they are sleeping.