Situated on 1,200 acres in Dutchess County, New York, about 80 miles north of the Rockefeller University campus, the Center for Field Research in Ethology and Ecology provides a setting for studying various organisms living under natural or seminatural conditions. The center has facilities for breeding and keeping animals indoors so that field and laboratory observations can be conducted in parallel. It currently supports a breeding program for the development of transgenic songbirds and field studies of ants. Past research has covered diverse topics, such as echolocation in bats, the incidence of stress in natural populations of animals, perceptual cues used during nocturnal migration, the biology of vocal learning in birds and the production of replacement brain cells in adult free-ranging animals. Equipment and facilities are available for descriptive and analytical research under both field and laboratory conditions.