Efeito da fragmentação vegetacional na reprodução de aves que nidificam em cavidades de barrancos em cursos de água

Abstract

Brazil holds 1919 avian species, which shelters 864 species only in the Cerrado domain. Some of this avifauna species breed near water courses, building their nests along ravines of banks with riparian vegetation. These areas have vegetation strips at different fragment sizes and different soil use. The vegetation fragmentation is a serious environmental problem that divides an original forest area into several portions along a spatial gradient, creating islands of native forest of different sizes, which can be isolated and without communication with others forest fragments. Therefore, this study aimed to test the effect of riparian vegetation fragmentation on the reproductive success of an assembly of birds that depends on this habitat for reproduction, on private farms and in the Natural Park of Morrinhos, south of Goiás. In this study, Spearman correlation analyzes were performed to verify if the fragmentation of riparian vegetation could interfere in the reproductive success rates of this group of birds. Data on the nests density per visited trail, egg hatch rate, the richness of species and number of eggs per nest were also analyzed. Sixteen areas of different fragment sizes of native forest were visited, with a total of 177 nests found, which 158 of them had eggs or nestlings and 19 were predated. The eggs success, nestling success and the overall reproductive success rates were presented for the species of Momotus momota, Galbula ruficauda and Tersina viridis, and afterwards the success of the bird community were also presented. It was also discussed about the importance of PPA’s (Permanent Protected Area) and their situation before the new Brazilian environmental legislation, about predation rates and about the reproductive period of this group of birds. The evaluated habitat reduction levels didn’t influence in a negative way on the reproduction of the studied group of birds. The reproductive success rates were similar for both well preserved area (74,19%) as well as fragmented areas (73,19%). The nestlings quantity didn’t influence on the survival of these birds, only on the Tersina viridis specie (75% of succes; n=22). The higher predation occurred on the egg season (44 eggs, 7 nestlings).