Primer registro de la gaviota sombría (Larus fuscus) en el estado de Veracruz, México: información sobre sus patrones de expansión en el Continente Americano

We report the first record of the Lesser Black-backed Gull ( Larus fuscus) for the state of Veracruz, Mexico. The range of this species has been expanding from western Europe into North America since the first half of the 20 th century until present. It breeds regularly in at least two areas in south-eastern Greenland, where the breeding population has been estimated at more than 700 pairs. Apparently, it is also expanding southward; since 1995 it has been recorded breeding in the Canary Islands. The first event of breeding in North America was in 2007 for Maine, USA. It was recorded in 1979 for the first time in Mexico. The species has been reported in six states, with a noticeable increase in the last few years. Our record occurred on March 16 th , 2008. Most birds recorded in eastern North America may have come from breeding populations either in Greenland or Iceland, which may be functioning as stepping stones between north-west Europe and North America. According to its migratory and range expansion patterns, and to an increase of nesting colonies, L. f. graellsii is the subspecies that may most commonly occur in North America. The morphological characteristics of the individual recorded in this work are consistent with such taxon. Considering the regularity and number of records of this species in different regions of the continent, it is likely that its presence might be underestimated in the Mexican coasts of the Gulf of Mexico, actually being a regular, although not abundant species.