Close to the Madding Crowd: Waterbird Responses to Land Use Conversion in and Around a Mediterranean Urban Wetland

Abstract

Investigating how Mediterranean wetlands respond to adjacent land use conversion, is an important first step in mitigating the impact of human encroachment and other environmental stressors. We monitored the composition and structure of waterbird assemblages, in a Mediterranean urban marsh, subjected to severe anthropogenic pressures. Remote sensing indicated that in the last two decades Boussedra Pond was subjected to landfill, resulting in a substantial reduction (~ 50 %) of the marsh, while due to a lack of urban planning urban built-up and agriculture areas expanded considerably in its surroundings. This precipitous reduction of the size of this urban pond threatens the diversity of its resident waterbirds which include the globally Endangered (EN) White-headed Duck Oxyura leucocephala, the Near-Threatened (NT) Ferruginous Duck Aythya nyroca, and many other staging and wintering migratory species. The long-term study suggested that breeding waterbirds species responded differentially to the loss and degradation of the marsh, as highlighted by the apparent resilience of the synanthropic Moorhen Gallinula chloropus and the disappearance of several breeding marsh specialists, such as the Little Bittern Ixobrychus minutus and the Western Marsh Harrier Circus aeruginosus. The study also points out the need for both a coordinated cross-sectorial land use planning and an immediate, affordable and sustainable wetland conservation action.