Ecological and Biological Behaviorof Nesting Colony of Bubulcus ibisin North-Western Algeria

We studied a colony of the Western Cattle Egret Bubulcus ibis located in the public garden on the northern outskirts of Chlef, north-western of Algeria, a site with 13 tree species; in this locality Cattle Egrets nested only on Ficus elastica, Jacaranda mimosifolia and Pinus halepensis. We observed the birds, each two weeks during the wintering period and weekly during the breeding season (February to August). To count the colony population, we used the method described by Dragonetti & Giovacchini (2009), called perimeter counts. Egg and nestling were recorded on 20 randomly selected nests and from different locations in each ofthe three nesting trees until all fledging. The number of Cattle Egrets at this site varied according to season, and was higher during the breeding season (1902 individuals) than during the wintering period (1210 individuals). Depending on the morphology of the trees hosting this colony, numbers of these birds varied from one tree to another. The nests observed are placed at relatively low heights, contrary to what has been described by some authors. Reproductive success is affected by the environmental conditions of the area and also by the physical and perhaps biochemical characteristics of the nest trees, but no difference in the location or orientation of the nests was noticed.