Uso de caixas-ninho pela fauna de vertebrados em relação às variáveis ambientais em um fragmento de Floresta Amazônica em Altamira-Pa

Abstract

The Amazon rainforest is considered one of the largest remnants of tropical rainforest in the world, but the sharp exploitation of natural resources in the Amazon has caused a growing loss of biodiversity. These impacts have worryingly reached the fauna that depends on natural cavities present in alive or dead trees as spots for nesting, sheltering or foraging. To compensate the loss of environmental complexity, the use of nest boxes has been successfully used, especially forests of temperate regions, for diverse groups of vertebrates, from birds to mammals. For the Neotropical region, it is necessary to evaluate the efficiency of this environmental intervention through the experimentation and observation regarding the use of these nest boxes in relation to the environmental variables, being our goal to develop these observations in a fragment of Amazon forest in Pará. The study used 30 wooden nest boxes distributed along a RAPELD research module located in a forest fragment in the Xingu region of Altamira. Eight boxes were installed in transect One and 16 transect the Two, added six boxes along the stream. Four boxes per parcel were installed, two at the beginning and two at the end, one 1.5 m hight and the other with 5 m. in relation to the ground; the boxes installed along the stream were fixed with intercalated height (1,5 and 5 m) distanced 50 m each other. Environmental and spatial variables were measured: opening the canopy edge distance, and an average density of the surrounding DAP trees, distance and altitude stream. The Principal Components Analysis (PCA), were used to correlate the occurrence of bird, amphibians and reptiles species, and used to verify the relationship between the nesting site variables and locations in relation to the sampling sites. Seven boxes were occupied by vertebrates, all then as sheltering. Four were occupied by mammals (Didelphidae and Rodentia), two reptiles (Thecadatilus rapicauda) and one amphibian (Osteocephalus taurinus). Sampling covered the entire study area through the heterogeneous distribution of the artificial cavities, there was slight variation between the variables and the nest boxes (PCA - 39.50% explanation of the axes). There was no significant correlation, but a tendency of use for T. rapicauda to occupy boxes associated with the variables distance of the stream and altitude, and mammals with the variable vegetation cover. Different from other Brazilian studies there was low occupation of nest boxes, and our results were not substantial to determine the use of nest boxes for environmental enrichment in fragmented environmental fragments in the Amazon.