Respostas à estrutura de hábitat e comportamento de forrageamento de tiranídeos no ambiente urbano

Abstract

Rapid urbanization brings a growing concern for ecological conservation. Birds are an excellent model to understanding the urbanization effects on wildlife, and tyrant-flycatchers are birds in the Neotropical more diverse in species number. The foraging behavior of birds is one of the biological aspects influenced by the structural complexity of the environment and its surroundings. In this context, the family Tyrannidae was used as a model for understanding how exploit birds the various environments at the urban area of Uberlândia, MG. This study has three habitats types: Streets, Squares and Areas change near to native vegetation remnants (APRs). In each environment were established 24 plots of 5,000 m² each. Structural variables were measured at each plot. The observations of tyrant-flycatchers were carried out from April to December 2009 from 7:00 to 11:30 am. Were performed 280 hours of observation. We registered richness, abundance and foraging behavior of flycatchers. The urban environments studied showed differences in relation to five of eight environmental variables studied. We recorded 28 tyrant-flycatchers species. Nine species were recorded exclusively in APRs and seven were common in similar numbers at three environments studied. There wasn t difference between urban environments studied in the flycatchers richness and abundance. There was a separation between the studied environments especially between APR and the other types of environmental, as a function of the composition of flycatchers species. Streets and squares didn t show visible pattern. The number of Tyrannidae species was positively related to the surrounding tree cover proportion, the number of plant species and the number of plants individuals taller than 6 m. Trees were the most frequent substrate used at search. The search strategies \"static\" was the most frequent and the one used by all species. The most frequent attack strategies were sally-strike and sally-hover . The most frequent substrates attacked during foraging were air , grass and live foliage . The average foraging height, the average sally time and searching time, and sally distance varied according to species. The most frequent attack direction was diagonal down or diagonal up. Behavioral responses to different environments were observed for the substrate height. There weren t changes in behavior in relation to average perch time, the number of perches used at searching, the sally distance of tyrant flycatchers. As for the attack behavior found that groups were formed according to the species regardless of the environment type. Flycatchers are good models for behavior studies at different environments. New studies with flycatchers at environments with vegetation clearly distinct, considering different scales of habitat, macro and micro, can be important to clarify possible behavioral responses to the environment.