Evaluating wildlife rehabilitation: successful return of rehabilitated gulls to the wild

Abstract The expansion of human activities has increased the need for animal rehabilitation, especially for urban-breeding species such as herring gulls (Larus argentatus) and lesser black-backed gulls (Larus fuscus), which now commonly nest on buildings and industrial sites. This study evaluates rehabilitation effectiveness by comparing survival and post-release reintegration, measured through habitat use and the degree of association with human-dominated environments, between rehabilitated and wild juvenile gulls along the Belgian coast. From 2012 to 2023, 3443 juveniles were ringed and monitored. Estimated apparent survival varied with age and species and was broadly similar between rehabilitated and wild birds, although rehabilitated lesser black-backed gulls showed slightly lower apparent survival than their wild counterparts. Differences in habitat use and association with local human population density were largely confined to juveniles: rehabilitated juveniles were resighted more often in intertidal areas with lower human population densities, with patterns converging in older age classes. Our results suggest rehabilitation can support urban gull populations by yielding broadly wild-like apparent survival.