Villagómez et al. Palabras clave: Gaviidae, Playa Azul, Distribución, Golfo de Tehuantepec. Primer registro del colimbo mayor (Gavia immerBrünnich AbstractWe recorded for the first time the Common Loon (Gavia immer) on the coast of Oaxaca state, Mexico. We observed an over-summering individual bird at the beach known as Playa Azul (07/13/2014), in the municipality of Salina Cruz, Oaxaca. The individual showed a non-breeding plumage, and has been observed in good condition. Due to the scarcity or lack of records by an irregular observation effort, the region could be considered as the natural distribution limit for the species.