Variation of the waterbird community relying to the Ichkeul National Park,Tunisia

For the period of 2001–2004, the detailed reaction of a waterbird community to dam building has been assessed in the Ichkeul National Park. Results showed that 71 species belonging to 8 orders were detected. Three herbivorous species were largely dominant: common coot (Fulica atra), common pochard (Aythya ferina), and Eurasian wigeon (Anas penelope). The three community parameters used in the analysis were: species richness, species abundance, and species diversity; which were significantly different between seasons. The wintering season was a key phase when the maximum values of these parameters were reached. This seasonal concentration of activity may be explained by migration. The upstream freshwater diversion was followed by a decrease in the annual abundance of the waterbird community due to the increasing salinity and the severe depletion of the swamp grass, Potamogeton (Potamogeton pectinatus). The total number of species was independent of the local conditions, and the annual variation was related to the number of uncommon species seen in each year.