Dogs density drives the reproductive effort of American Oystercatchers (Haematopus palliatus) in disturbed habitats of the Maule Region, central Chile

The American Oystercatcher ( Haematopus palliatus ) is a shorebird specialized in coastal environments across the Americas. Thus, anthropic extensive use of the shoreline including the introduction of dogs and vehicles to beaches could directly impact fitness, and ultimately the persistence of the species’ populations. In this study, we aimed to assess the impact of pedestrians, vehicles and dogs on the nest density, productivity and hatching success of the American Oystercatcher in the Maule Region, central Chile. To this end, we sampled sandy beaches, quantifying the number of nests, eggs, chicks, but also pedestrians, vehicles and dogs during the breeding seasons of 2023 and 2024. We assessed for the influence of these threats on parameters of reproductive output by using Generalized Linear Mixed Models. We found that the number of dogs is the only variable that negatively impacts the number of nests, eggs and chicks of the American Oystercatcher in the sampled areas. Reducing the impact of dogs is a ubiquitous challenge in coastal environments of central Chile, however current regulations do not allow management relying on removal of dogs from important areas for biodiversity.