Resposta da avifauna de sub-bosque à inundação sazonal das florestas alagáveis da Amazônia

Abstract

The annual flooding in the Amazon basin transforms the understory of the floodplain forests into an aquatic environment, mainly influencing terrestrial organisms. However, a great diversity of non-aquatic birds occurs exclusively in wetlands. In general, these birds are considered sedentary and territorial and the way they adapt to this drastic seasonal transformation has never been described in detail. In this study, we described the understory avifauna adaptation strategies to the seasonal flooding in the floodplain forests in the region of the lower Purus River, central Amazon. We conducted focal searches with five species in wetlands and on dry land, on the flooded and dry seasons. For each observation, the height of the bird above the substrate (soil or water), its vertical position and measures of vegetation density around the bird (micro-habitat) were recorded. All species remained present in the floodplain forests during the two seasons and were not recorded on the mainland. In general, we observed that the species have specificities when using the vertical space, and that they all migrated vertically across the vegetation from drought to flood. Despite the general increase in the relative position of all species, there was a reduction in height above the substrate of the species, except for Myrmoborus leucophrys. The vertical movement was added to the strategy of changing micro-habitat between seasons for two species, Galbula tombacea and Hypocnemoides melanopogon. It is likely that the decrease in the vertical space available in the flood, together with other associated factors, such as similar displacements in their arthropod prey and redistribution of species in the environment, indirectly affect avifauna and influence adaptation seasonal.