Avifauna de uma área de transição cerrado–amazônia: composição, abundância, riqueza e variação diária na taxa de captura.

Abstract

Few studies have focused on the avifauna of the Cerrado-Amazonia ecotone. Being so, we investigated the composition of the avifauna, and the daily fluctuations in species richness and abundance of birds in a Cerrado-Amazonia transition zone in the municipality of Ribeirão Cascalheira, Mato Grosso, Brazil. We sampled local bird populations between July, 2012, and October, 2014. We captured birds in mist-nets, which were set in two different environments: in the interior of the forest and in open areas adjacent to water bodies. We recorded significant variation in the abundance of birds in the two environments among the different hours of the day (χ2 = 219.98; df = 13; p < 0.001). Captures peaked at 7:01–9:00 h (145 individuals; p < 0.001), 9:01–11:00 h (n = 117; p < 0.001), 15:01–17:00 h (n = 63; p = 0.041), and 17:01–19:00 h (n = 70; p = 0.041). We recorded similar diurnal variation between environments in bird species richness (χ2 = 127.89; df = 6; p < 0.001), with the number of species peaking at 7:01– 9:00 h (93 species; p < 0.001), 9:01–11:00 h (55 species; p < 0.001), and 13:01–15:00 h (39 species; p < 0.001). Overall, we recorded 103 bird species, distributed in 34 families, of which 21 belong to the Passeriformes, and the other 13 to non-passeriform orders. The most diverse non-passeriform families were Columbidae (n = 6 species), Trochilidae (n = 5), and Alcedinidae (n = 4), whereas the richest passeriform families were Thamnophilidae (n = 19), and Thraupidae, Dendrocolaptidae, and Tyrannidae, with seven species each. The diurnal variation in bird captures was distinct in the two sampled environments, indicating fundamental differences in activity patterns. Overall, the composition, abundance, and species richness of the birds of the Cerrado-Amazonia ecotone appear to represent a unique avian fauna, typical of this region, which requires further investigation.