Gender-related diet composition and morphometry of the Restinga Antwren, Formicivora littoralis (Aves: Thamnophilidae)

Formicivora littoralis (Gonzaga and Pacheco, 1990), the Restinga Antwren, considered the only endemic bird species of the Restinga ecosystem (sandy plain coastal vegetation), is threatened with extinction. The scientific literature provides little information on the biology of this bird, which was discovered in 1990. We evaluate gender-related differences in the composition of the diet and morphometric measurements of this species. We tested the hypothesis that the sexes differ in what they eat and in morphometric characters. Our results revealed that the diet of the Restinga Antwren includes mainly arthropods, which is consistent with the diets of other Thamnophilidae. The lack of differences in the composition of the diet between the sexes does not support the hypothesis that habitat partitioning to avoid intraspecific competition is taking place. We found significant differences in six morphometric measurements, two in the beak and four in body size. It is possible that intraspecific differences between the sexes are a result of sexual selection, a hypothesis that needs to be tested.