Avian Conservation and Ecology (Dec 2021)
Population trends and habitat selection of threatened marsh passerines in a protected Mediterranean wetland
Abstract
Many marsh passerines are cataloged as threatened taxa, mostly due to their high degree of specialization and the generalized deterioration of wetlands worldwide. In this context, habitat selection studies are a very helpful tool to achieve optimal wetland management, take appropriate conservation measures, and avoid potential conservation conflicts resulting from species-specific habitat requirements. For this purpose, we analyzed the population trends and habitat requirements of the threatened marsh passerine community inhabiting a protected Mediterranean wetland with persistent hydrological problems due to aquifer overexploitation. Listening points were conducted yearly for eight consecutive years (2012-2019), and habitat categorization and abundance estimation of the target species (Great Reed Warbler, Acrocephalus arundinaceus; Moustached Warbler, Acrocephalus melanopogon; Reed Bunting, Emberiza schoeniclus witherbyi; Savi's Warbler, Locustella luscinioides; Bearded Tit, Panurus biarmicus) were performed at each point. Our results show that the populations of the Great Reed Warbler strongly declined during the study period while those of the Reed Bunting increased; the remaining species experienced an initial increase in abundance but have declined in recent years. The habitat type, measured as relative cover of common reed, saw sedge, bulrush, dry vegetation, open water, and dry surface was important to explain variations in the marsh passerine community structure. Focal species showed different, and even opposite, habitat requirements over the course of eight years, but the abundance of all species seem to be conditioned by disturbances in the wetland water regime. Conservation implications, including the importance of wetland hydrological regime and the presence of heterogeneous environments, are discussed in order to provide relevant information for the conservation of the marsh passerine communities of Mediterranean wetlands.
