Clipperton Atoll lies in the eastern Pacific Ocean about 1000 km southwest of Guerrero, Mexico, at 10°18'N, 109°13'W, and, like many remote islands, is visited rarely by biologists. Although known mostly as a major breeding ground for seabirds, 29 species of northern migrant birds have been reported from the island (Beck 1907, Ehrhardt 1971, Gifford 1913, Haeze et al. 1967, Howell 1959, Niaussat et al. 1968, Stager 1964).