Dam effects on the wintering strategy and habitat use of Greylag Goose (<Emphasis Type="Italic">Anser anser</Emphasis>) in Ichkeul National Park,North Tunisia

The mosaic of habitats in the Ichkeul National Park is frequently changing due to the variations in water conditions that had influenced the wintering strategy of waterbird populations. To this point of view, field work on the wintering strategy of Greylag Geese in the Ichkeul National Park was realized during two consecutive winters (September 2001–March 2002 and September 2002–March 2003). Results showed that in this area, the Greylag Goose was a regular winter visitor, typically from the beginning of October to the end of March, when food resources were totally exhausted in all marshes. Records of diurnal time budget revealed that feeding (43%) and sleeping (20%) dominated all other activities: walking, flying alertness, and preening. The food resource depletion might be the principal responsible for the total population size decreases, the behavioral changes, and the switch of habitats used by the considered species. This situation is a kind of alarm bell to indicate a perturbation of the habitats in the Ichkeul National Park. Therefore, it is essential to use appropriate management strategies to enhance the value of this area for the bio-indicator species, in particular Greylag Goose which is very sensitive to habitat changes.