文摘
In the Mediterranean basin, the yellow-legged gull Larus cachinnans has undergone a widespread demographic increase for the past 30 years. Owing to its high ecological adaptability, its aggressive behaviour and its abundance, this gull is often considered to be a pest. The authors review and analyse the impacts of the expansion of the yellow-legged gull on fauna and flora in the Mediterranean area. Despite the relatively limited number of both intensive and general studies, it clearly appears that the population explosion has had a very diverse and severe effect on the ecosystem as a whole (flora, vertebrates, interspecific competition, extinction–colonization processes). The most serious damage has occurred around the largest breeding colonies to the detriment of fragile, rare or very restricted plant and animal species. Thus, from the point of view of fauna and flora conservation, the yellow-legged gull can, for the moment, be considered to be locally superabun dant. Control measures are often very onerous and necessitate heavy manpower and material resources. Additional extensive investigations will be necessary to assess the future development of yellow-legged gull populations and their impact on natural environments.