Diversity patterns and seasonal variation of the waterbird community in Mediterranean wetlands of Northeastern Algeria

Abstract

During two annual cycles (from September 2012 to August 2014), we analysed structural patterns (provided and compared data on diversity metrics) of bird assemblages in coastal wetlands of Northeastern Algeria. Annual and seasonal differences in relative species abundance were analysed from the viewpoint of diversity/dominance. Bird assemblages vary only in the number of species (35 recorded species during the wintering season against 23 during the breeding season). Values of the relative abundance in both seasons were similar, curves in the diversity/dominance diagram were analogous (not significantly different; both p > 0.05). Indeed, the seasonal structure of waterbird communities indicates highly dominated assemblages manifesting themselves in reduced species diversity and increased dominance of certain species. Simpson’s index was never recorded below 0.50, thus indicating evidently lower evenness. The Eurasian Coot Fulica atraand the Little Grebe Tachybaptus ruficolliswere highly dominant species together accounting for more than 50% of waterbird communities. This atypical organisation (highly dominated structure) is mainly due to anthropogenic or natural stresses. The marked decline in bird species diversity recorded during the study period (approximately two years long) may be of concern to wetland managers as causes and consequences of the increased number of widespread species and factors behind the increasing species diversity are likely to be felt in both seasons.