Behavioral responses of urban birds to human disturbance in urban parks at Curitiba, Paraná (Brazil)

Abstract

Proximity to humans can influence behaviors that are essential in birds' life, such as breeding, foraging and flight. In urban parks, which are important natural shelters to birds, human activity varies broadly in time such that attentiveness and escaping behavior of birds may be intensified as humans' density increases. In this study, we tested this hypothesis in six urban parks at Curitiba, southern Brazil, using three common bird species as models, the Rufous Hornero (Furnarius rufus), the Southern Lapwing (Vanellus chilensis) and the Rufous-bellied Thrush (Turdus rufiventris). Specifically, we tested if foraging rate, alert distance (AD), flight initiation distance (FID) and flight distance (FD) were related to human density at birds' surroundings. We found no influence of humans on birds foraging rate, whereas AD, FID and FD decreased with human density in the area. We also found differences in birds escaping strategy; “flying” strategy was associated with higher AD, FID and FD than “walking”. Results also indicate that humans' presence temporally affected birds' vigilance and flight responses, evident through their constant foraging rate irrespective of human density, i.e. increased tolerance to human proximity. Our study provides evidence of behavioral plasticity of the model species to the intensity of human use of their living area, which also highlights the importance of further efforts in creating refuges within urban parks to minimize negative anthropic impacts on urban species.