Roof nesting by gulls for better or worse?

Since the early 1970s in Italy, the yellow-legged gull Larus michahellis has been colonizing new kinds of nesting areas, in particular moorland and the rooftops of inhabited buildings. The incidence of rooftop colonies is now such that the yellow-legged gull has come in many urban areas to be regarded as a pest. Yet its colony structure and breeding biology in the urban situation in Italy have remained largely undocumented. This paper reports observations of yellow-legged gulls breeding in the town of Venice and in the surrounding lagoon during the 2003-2005 breeding seasons. The aim of this study was to examine the performance of birds breeding in natural and urban areas and to investigate the links between the natural and the newly established urban colony. For this, we analysed and compared factors indicative of breeder quality. Breeding performance was not substantially different in the two colonies. This suggests that gulls are successfully exploiting a new habitat, adapting to new resources, as other opportunistic species d

Effects of a new waste collection policy on the population of yellow-legged gulls, Larus michahellis, in the historic centre of Venice (Italy)

Urban sprawl represents one of the most critical threats to biodiversity leading to the decline of rare and specialist species and the proliferation of a few dominant generalist ones. Among the winners there is the yellow-legged gull, Larus michahellis, which has recently colonised towns, nesting on the roofs of buildings and feeding on urban waste by spreading the contents of garbage bags on the streets. This situation has been recently documented in the historic centre of Venice (Italy) where it led to negative environmental impact and serious consequences in terms of urban hygiene. To counter such problems, the public company responsible for managing the urban waste in the Venice municipality established a new waste collection policy in the city to prevent accumulation of rubbish in the streets and limit the amount of trophic resources available for the species. We performed a monitoring program of the urban population of yellow-legged gulls and used generalized linear models to investigate the effectiveness of the new waste collection system on reducing the amount of waste in the streets and its effect on the target species. Results revealed a statistically significant positive correlation between urban waste and gulls and a significant effect of the new policy in lowering these two variables. Open areas, strongly frequented, with food and beverage vendors and illegal dumps were also highlighted as the main contributors to the presence of yellow-legged gulls. Such information can be used by local authorities to plan specific interventions to reduce the attractiveness of the city to gulls

Long-term estimates of adult survival rates of urban Herring Gulls Larus argentatus

Urban gull populations have increased dramatically in the last 40 years, leading to widespread concerns about potential nuisance to humans, but little accompanying research into their ecology. This study aimed to provide the first long-term estimates of apparent adult survival rates for urban Herring Gulls Larus argentatus and Lesser Black-backed Gulls L. fuscus, based on colour ringing in Bristol, southwest England. Resightings of adult birds covering 18 years (1990–2007) were analysed using capture–mark–recapture methods, with candidate models testing for differences in survival and/or resighting rate through time and between the sexes. Both species showed high apparent annual survival rates (>0.90) in the early 1990s that declined to <0.70 by 2007. Male survival rates were higher than female rates in Lesser Black-backed Gulls, and male resighting rates were higher in both species. In the early 1990s, Bristol's urban gulls displayed similar adult survival rates to published estimates for rural colonies. Both species showed evidence of long-term declines in apparent survival, which may either reflect actual reductions in survival or increased permanent emigration from the Bristol colony. Anecdotal evidence supports the latter, linking emigration to urban redevelopment or human intervention