Little is known about the distribution of the Least Tern (Sterna antillarum) along the Pacific coast of Mexico. It breeds locally (April–August) from northwestern Baja California and the northern Gulf of California south to Chiapas (Howell and Webb 1995; Thompson et al. 1997). From Nayarit southward, it has been reported either as a migrant (Schaldach 1963; Escalante 1988) or as an uncommon permanent resident (Álvarez del Toro 1980; Binford 1989; Villaseñor 1990; Thompson et al. 1997). However, these broad statements are based on relatively few specific observations.