Seasonal variation in habitat use, daily routines and interactions with humans by urban-dwelling gulls

The effects of growing urbanization have caused an increase in human-wildlife interactions in urban areas. Human-gull conflicts have been particularly studied during the breeding season when gulls cause an obvious nuisance in urban areas. However, with many gulls being present in urban areas throughout the year, stakeholders need knowledge of seasonal effects on local human-gull interaction dynamics. Here we present a comprehensive study on spatial and temporal variation of urban habitat use and human interactions with urban gulls, Larus spp., in Porto, Portugal. The work combined: (1) a large-scale study, using year-round monthly surveys to quantify gulls’ behaviour and their use of multiple urban habitats, with (2) a small-scale study, using 10-h daily urban surveys to capture gulls’ daily routines and interactions with humans during the winter and breeding seasons. We found a strong temporal effect in the number of gulls and human-gull interactions occurring in urban areas, with both highly increasing during winter. Habitats with higher urbanization intensity were mainly used by adult gulls, and the number of breeding-related conflicts reported by the human population peaked during the chick-rearing period. Still, during winter, several adult gulls kept occupying their rooftop nesting grounds, and the number of individuals foraging and interacting with humans in city-squares increased. This was mostly triggered by humans feeding birds. Therefore, when designing urban management landscape measures, seasonal variations of the urban gulls’ behaviour and habitat-use should be considered, as well as anthropogenic activities and human behaviour.