Urban and coastal breeding lesser black-backed gulls (Larus fuscus) segregate by foraging habitat

Despite urbanization's general erosion of biodiversity, towns and cities provide novel opportunities for some species. During the 20th century, gulls (Laridae) colonized urban areas around the world where they flourished. At the same time, some coastal populations declined. The reasons for this difference are not fully understood, partly because little is known about any ecological differences between urban and non-urban gulls, such as their foraging ecology. Here we compare the movement ecology and habitat selection of Lesser Black-backed Gulls Larus fuscus graellsii breeding at two neighbouring colonies - one urban and one coastal - in north-west England. We used bird-borne GPS loggers to first compare colony-level movement behaviour and habitat selection and then investigated individual-level habitat use. We observed clear colony-level habitat segregation: urban breeders preferentially foraged in urban areas whereas coastal breeders foraged primarily in coastal habitats and avoided urban areas. Coastal breeders also had larger core and home-ranges than urban breeders, possibly due to differences in colony size. However, we also found inter-individual differences in habitat use, which may have important management implications. These findings suggest a link between nesting and foraging ecology, and thus management or environmental change altering food availability will impact gulls at the coastal and urban sites differently.

Automated summary

Despite the negative impact of urbanization on biodiversity, urban areas provide unique opportunities for certain species. This study compares the movement behavior and habitat selection of Lesser Black-backed Gulls breeding in an urban colony and a coastal colony in north-west England. The results show that urban breeders prefer to forage in urban areas, while coastal breeders primarily forage in coastal habitats and avoid urban areas. Additionally, individual variations in habitat use were observed, which may have implications for management strategies. These findings highlight the link between nesting and foraging ecology and demonstrate that changes in food availability will affect gulls in coastal and urban areas differently.