Response of specialized birds to reed-bed aging in a Mediterranean wetland: Significant changes in bird biomass after two decades

What is it about?

In this work we compared, through a wide temporal range (2001-2019), the densities of four habitat-specialized birds (warblers), strictly linked to Phragmites australis reed-beds in a coastal wetland on the Tyrrhenian central Italy. We observed as in this wetland, following the abandonment of fish farming, the averaged density of reeds significantly decreased, and both the averaged reed diameter and habitat heterogeneity showed a significant increase. Comparing 2001 to 2019, we observed also an increase of total density of breeding warblers. The two species of Acrocephalus (scirpaceus and arundinaceus), and Cettia cetti showed a marked increase in density, while Cisticola juncidis showed a clear decrease. More particularly, a significant increase in Cettia cetti (p<0.001) and a decrease in Cisticola juncidis (p<0.05) emerged when comparing bird biomass. Species diversity and evenness were more high in 2019 when compared to 2001. Our data suggest: (i) as these species could be considered indicators of long term reed-bed changes and (ii) as biomass may be used as a more effective metric when compared to abundance. _x000D_ We revised the ms as requested by the Reviewer. Thanks.

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