Trees and people determine the feeding activity of a migratory bird in an urban mega-park of Mexico city

Abstract

Feeding research is relevant to comprehend wildlife use of urban systems and to guide management practices. Coupling foraging with habitat assessments is important because environmental conditions affect animal access to food, leading to variations in behaviours and the numbers of feeding individuals. Still, we have little comprehension about the foraging ecology of animals in Neotropical cities. We analyzed the feeding use of an urban mega-park by a migratory bird in Mexico City, central Mexico. We used distance sampling and hierarchical models to identify the habitat traits that determined the feeding density of the Yellow-rumped (Audubon’s) Warbler ( Setophaga coronata auduboni) in the Chapultepec mega-park. Moreover, we evaluated the spatial variation of the feeding behavior of the species across the site and compared the substrates that this warbler used for foraging by utilizing a Bayesian modelling approach. We included observations from a grey area adjacent to the mega-park for comparison purposes. Our results demonstrated that the number of feeding individuals of the Yellow-rumped Warbler was determined by tree species richness and the number of pedestrians. Greater numbers of tree species might foster the diversity and availability of food resources for the warbler, whereas the number of pedestrians might increase risk perception by birds, reducing their foraging activity. The variation in the proportion of feeding occasions among the sections of Chapultepec supported the pattern associated with our feeding density analysis. The species fed most frequently on trees than in any other substrate. Thus, we showed that urban green areas provide important feeding grounds for the Yellow-rumped Warbler during the migratory period, particularly where tree species richness increases and human activity reduces. Management and restoration activities across the mega-park should be directed to foster tree species richness and mitigate the impact of human activities to enhance the feeding activity of migratory birds.