Ecologia comportamental de Tyrannidae (aves: passeriformes): mudanças nos padrões de forrageamento em resposta a variações ambientais e sazonais em ambiente urbano

Abstract

The next few decades, more than half of the world's population will be concentrated in urban environments and the impact of urbanization on native species is certainly not small. In this context, investigate the behavioral adjustments of animals in response to urban pressures, can provide essential subsidies for the biodiversity conservation. Because of the ubiquity, numerical dominance and occupation of many different environments, Tyrannidae family bird constitute an excellent model for understanding the behavioral responses to structural differences in habitat and seasonal variations. This thesis presented is that Tyrannidae family birds in urban areas change their foraging behavior in response to the type of urban environment and different seasons. Birds with distinct foraging micro-habitat will vary their responses to the seasons and the different urban environments. And the original native habitat and flycatcher foraging mode will be decisive in the patterns of behavioral responses to seasonal variations in the urban environment. The study was conducted in the urban area of Uberlândia, Minas Gerais, Brazil, from 2012 to 2014.We established 30 plots in each type of urban environment (square and park). For the record of flycatcher behaviors each plot was sampled for at least 50 min. We used a sequential sampling method with time intervals. To check for possible seasonal and environmental differences in foraging strategies and use of plant we performed the Chi-square and the Mann-Whitney tests. Tyrant flycatchers-plant interaction networks were built to plant substrates used during the search and attack behaviors. Tyrant flycatchers, gleaners and hawkers, varied more behaviors in response to the seasons. Tyrant flycatchers considered essentially grassland varied behavioral aspects more related to the selection of foraging micro-habitat, while essentially forest species varied time attack, distance and perch as a mechanism to compensate the stability of its micro-habitat foraging. Essentially grassland tyrant flycatchers showed preference for native plants in the dry season. The three species of tyrant flycatchers using different foraging microhabitats had more behavioral changes, due to environmental differences, and higher variability of behavior in response to seasonality. The aerial foraging species appears to be more exposed to the urban impacts, depending on the prey availability and diversity on the seasons. The tyrant flycatchers foraging on micro-habitats with elevated perches increased the foraging height at places with higher human disturbance. The tyrant flycatchers almost never varied the foraging tactics related to search and attack behavior, these are more restricted by their morphology. Considering the plant used in the attack, the analysis of network tyrant flycatchers-plant interactions on dry season presented modularity probably as mechanisms to minimize competition. The micro-habitat foraging type used by the tyrant flycatchers was more restrictive to define patterns of responses to environmental changes that seasonal. Response Patterns to seasonal variations in foraging behavior suggest that their evolutionary history (natural habitat of origin) is more important than foraging mode for behavioral changes to respond to the seasons at the urban environment.