Urban and Wild Kelp Gulls: Tracking Seasonal Shifts in Habitat Use and Movement Patterns

Humans impact the environment through a myriad of activities, including urbanisation. While some wildlife species struggle to cope with urban development, others might benefit from it. Kelp gulls (Larus dominicanus) population growth has been linked to the availability of anthropogenic resources; however, there is limited knowledge about their habitat use and movement patterns year-round. Here, we tracked Kelp gulls (n = 8) in Northern Chile from December 2022 to December 2023 using GPS-GSM devices. Our goal was to gain understanding of their habitat use and movement patterns throughout the year, and to test for differences between an urban colony at Coquimbo and a wild colony in Damas Island. We found that both wild and urban gulls used natural habitats such as the open sea and wetlands, as well as anthropogenic habitats, such as landfills and fish markets. Wild gulls undertook longer trips and travelled greater distances than urban gulls, and this was attributed to wild gulls' colony being farther from predictable food resources. In addition, there were differences in habitat use and movement patterns across the seasons. During the breeding period, wild gulls use anthropogenic habitats to a lesser extent than urban gulls, but during the post-breeding period, wild gulls ventured farther from their colonies to more anthropogenic habitats. Although based on a limited sample size, we found that urban gulls behave as synanthropic animals, showing reduced mobility year-round, whereas wild gulls' movements suggest that they are adapting to shifts in their breeding responsibilities and to variations in food availability. Beyond contributing to gull ecology, these findings provide valuable information for conservation and management planning.