Health Stress in Birds Increase with Urbanization in a Large Tropical City

Understanding how the urbanization process affects the lives of animals that live in these environments is relevant to conservation and management. In fact, the urbanization process has a direct impact on animals and can influence their health state. Thus, our objective was to investigate the immunological response of birds to the urbanization process. We recorded the H/L ratio of 723 birds of 10 species captured in Brasília (a large city in central Brazil), as a measure of chronic stress in birds. The H/L ratio was positively associated with the intensity of urbanization and negatively associated with body condition. However, body condition was not associated with intensity of urbanization. We confirmed our hypothesis that birds living in areas with greater urban intensity are more stressed. In addition, we demonstrated that the H/L ratio is negatively associated with body condition, and that this variable should be considered in studies that aim to assess the health of animals. These findings are relevant because they confirm that the urbanization process, along with all its environmental changes (increased artificial light, increased noise, suppression of vegetation, increased built-up areas, etc.), has a negative direct impact on wild populations, which have to deal with major urban changes.