Avifauna de duas áreas do Parque Nacional de Ilha Grande, Paraná, Brasil

Abstract

This study was developed in two areas in the southern portion of the Ilha Grande National Park (23 º 59 'and 24 º 04' S and 54 º 09 'to 54 º 15' W) in Guaira, Parana. The objective was to compare and analyze the bird communities in these two areas between the months of April 2009 and March 2010. The first area is formed by the Pacu Island and three small islands in its adjacency (total area of 97.34 ha) and it is closer to the center of human disturbance. In these islands were distributed 13 observation points. Already the area is formed by Robinson, Scott and San Francisco Islands (total area of 100.40 ha) and 14 observation points. For the birds sampling was used the fixed points method. During the study period, there were 20 expeditions to Area 1 (442 point samples) and 17 expeditions to Area 2 (448 point samples). We recorded 123 bird species, 99 in Area 1 and Area 2 107. Sixteen species (16.16%) were unique to one area and twenty-four (22.4%) exclusive Area 2. We recorded two endangered species in the Paraná State (Sporophila angolensis Procacicus solitarius), both with high frequency of occurrence, besides the first record of Icterus croconotus in this state. The Abundance Index changed by 0.0022 (a contact) in fourteen species in both areas and 0.6651 (294 contacts) just to Todirostrum cinereum in Area 1 and 0.5647 (253 contacts) just for thrush in leucomelas Area 2. The birds variety was 3.332 in Area 1 and 3.517 in Area 2. The equidistribution of the species was 0.725 for Area 1 and 0.752 for Area 2 with similarities between the areas of 0.80. Frugivorous and scavengers have similarity of 0.5 between the study areas, followed by insectivorous (0.46), omnivores (0.45), granivores (0.41) and carnivores (0.38). The omnivorous represent 41.46% of the 123 species recorded in the survey, followed by insectivores (30.89%), granivores (10.56%), carnivores (7.31%), piscivores (4.87%), frugivores (2.43%) and scavengers (2.43%). The low incidence of frugivores raises an alert for this ecosystem. Probably the great enterprises and intense process of deforestation in the region may have been responsible for the negative effects on bird community. The study showed no statistical difference in the results for the calculated parameters in different areas. These results are explained by the fact that the factors of human disturbance may have also affected areas, besides proximity and similarity in habitat between areas (mean distance of 8.5 km.). These results were the first systematic data about the lake avifauna after the creation of the Itaipu hydroelectric plant and the construction of Ayrton Senna Bridge and they can support studies for forecasting, mitigate and compensation for the environmental impact for future enterprises in near of the study area