Food resources availability and exploitation by the Cattle Egret Bubulcus ibis in Kabylia, Algeria

Cattle Egrets (Bubulcus ibis) living in the Sebaou valley, Kabylia, Algeria , have a diet based mainly on insects, which represent 97.1% of food items and 57.2% of ingested biomass, calculated after 5 999 prey items recovered from 150 rejection pellets collected in three different colonies. Orthopter an insects in particular account for 47.3% of the ingested biomass. Vertebr ates are few in terms of preys (1.5%), but represent 42.5% of the ingested biomass. They seem to be captured when the Egrets get an opportunity to do so, i.e. after crossings of agricultural engines. Variations in the diet of Cattle Egrets from one colony to the other, as well as variation according to months seem to be correlated to the local availability and phenology of preys. Cattle Egrets in one region visit various biotopes according to pre y availability and their own food requirements. In the Sebaou valley as wel l as at other places, Cattle Egrets appear to be opportunist feeders which, when preys are abundant, choose the ones fitting best their nutritional re quirements, but which can make use of the remaining ones when food becomes scarce. This ability may partly explain the Cattle Egret's recent, successf ul range extension in Algeria.