Current distribution and predicted geographic expansion of the Rufous-backed Robin in Mexico: a fading endemism?

Aim The Rufous-backed Robin Turdus rufopalliatus is a bird endemic to the Pacific slope of Mexico. The species recently established populations in several localities in the Mexican Central Highlands. Based on available data, we modelled the range expansion of the Rufous-backed Robin in Mexico to understand the pattern, mechanisms and ecological and biogeographic implications of its expansion. Location Mexico. Methods We assessed the species' presence and habitat requirements at two spatial scales. At the site level, we evaluated the relationship between land use and species presence in an urban environment. At the country level, we generated a niche model. We then produced a dispersion model through the interpolation of points generated from information derived from the niche model, the location of records within and outside its native distribution range, the species' natural history, habitat requirements and its estimated dispersion rate (4.2 km year-1). Results The dispersion model predicted that the species will significantly increase its distribution range in Mexico in the coming decades. Its expansion would occur by a stepping-stone colonization of suitable habitat in areas of native vegetation and human settlements. The model predicted that the species should arrive on the Gulf slope of Mexico before 2025. Main conclusions Mechanisms that could explain the species' success in establishing viable populations outside its native distribution include its dispersion ability, competitive release, the urban heat island phenomenon and the trade of wild birds. The geographic range expansion of the Rufous-backed Robin will probably create new interactions with other species, particularly with close taxonomic and ecological relatives. The increase in the distribution range of the Rufous-backed Robin has resulted from direct and indirect human-induced dispersion; therefore, it cannot be considered a fading endemism. In part of its expanded range (to date the Mexican Central Highlands), it should be considered an invasive alien species.