Influence of landfill use on nest-site selection and breeding success in white storks

Abstract

Landscape transformation by humans through habitat degradation, agriculture intensification and urbanization results in the loss of natural feeding areas. However, populations of certain species have adapted to these changes and benefit from some anthropogenic food sources as well as an absence of predators and milder environmental conditions in urban landscapes. Although breeding near landfills secures food availability and saves energy and time spent on foraging activities, the poor food quality and risks associated with these facilities imply some fitness costs. Our study shows the effects of landfills on nest-site selection and breeding success in white storks (Ciconia ciconia). Birds breeding near landfills occupy more urban areas where many structures are available to nest, while breeding pairs 20–30 km from landfills select nest sites with high-quality food sources in the vicinity such as pastures, meadows and agro-forestry areas. Furthermore, we demonstrate that habitat quality in the surrounding area is more relevant than landfills for breeding outcomes, but both of these are crucial for brood size. The number of fledglings was higher at a medium distance to the landfill than at 20–30 km from the landfill, but not near the landfill (0–10 km). This suggests that the best strategy includes food from landfills as a complementary or alternative food source. Future studies should further investigate if these shifts in habitat preference are permanent, and the potential impact of habitat degradation and landfill closures at a population level, for this species.