Factors Affecting Colony Size and Reproductive Success of Little EgretEgretta garzettain the Sfax Salina, Tunisia

Abstract

The relationship between breeding site characteristics and breeding parameters of Little Egrets were investigated in the Sfax salt marshes (salina), Tunisia. Thirty colonies distributed among 14 breeding sites were monitored weekly during four breeding seasons (2004–2007). The number of breeding pairs varied among years in parallel with the number of detected colonies. Regressions were used to assess whether breeding site surface area, vegetation cover and inaccessibility to terrestrial predators affected the size and reproductive success of the colonies. Colony size was positively related to breeding site surface area and vegetation cover, while site isolation was the most important predictor of chick productivity. The results suggest that Little Egret colony size in the Sfax salina is determined by availability of nesting places, while chick productivity is controlled by accessibility of breeding sites to terrestrial predators, i.e. dogs. Given these results, an effective management action to conserve Little Egrets in Sfax would be to strategically place fences to protect large and densely-vegetated islets from these predators.