We describe the migratory pattern of black terns (Chlidonias niger) in the Ojo de Liebre-Guerrero Negro coastal-lagoon complex and Guerrero Negro saltworks on the Pacific coast of Baja California Sur, Mexico. Most black terns (97% of total) were seen July–October, with 6,700 birds being the highest count per month (September). During spring, this species was observed only in April (220 individuals). We recorded 90% of black terns in the southeastern portion of Ojo de Liebre Lagoon, where they were in artificial (saltworks) and natural habitats (marsh and sandy shallows). In late summer (July–August), 94% were in the lagoon, by contrast, in autumn we recorded 96% in saltworks. Overall, black terns are a common transient in Guerrero Negro during summer and autumn and uncommon during spring. Black terns use these artificial and natural habitats as stopover areas during migration.