Geographic and seasonal distribution of a little-known Brazilian endemic rail (Aramides mangle) inferred from ocurrence records and ecological niche modeling

Abstract

Regional, intratropical avian migrations have rarely been studied. Here, we employ an occurrence records review and ecological niche modeling tools to test the hypothesis that an understudied Neotropical bird, the Little Wood-Rail (Aramides mangle, Rallidae), seasonally migrates between the humid Atlantic coast and the dry Caatinga biome of interior northeastern Brazil. We divided records geographically between coastal and inland, and temporally between wet/breeding and dry/non-breeding seasons. Coastal records peak when inland records are fewest and vice-versa, and independence between season and region in which records were made was statistically rejected. However, ecological niche modeling shows that coastal regions are suitable habitats for A. mangle year-round, and models built with records from each season were considered statistically equivalent. It seems that this species neither performs erratic, unpredictable movements nor typical avian “to-and-fro” migration. Instead, it undergoes periodical expansion of its range and ecological niche to include the Caatinga, where it breeds, in addition to the coast. It might be counterintuitive that a species can occupy two seemingly so disparate habitats, but rails in general are known to be very adaptable and have wide ecological niches. Further study is needed in order to understand the exact nature of this species' movements and the life-cycle of individual birds. But given that most studies of avian movements have focused on temperate species, it is likely that common models of avian migratory behavior will not easily apply to A. mangle nor to other Neotropical species.