The breeding biologies of the Cattle egret Ardea ibis, the Little egret Egretta garzette, the Squacco heron Ardeola ralloides, the Black-crowned Night Heron Nycticorax nycticorax, the Purple heron Ardea purpurea and the Glossy ibis Plegadis falcinellus, were studied in the mixed breeding colony at the Lac Tonga on 2000. The colony consisted of about 3548 pairs. The nesting season lasted from the end of March to July. Nests are built from 0,1 m to 4,25 m. Mean, nest heights differed significantly among species (P<0,000 1). Mean clutch size was 4,25 (± 0,961) for Little egret, 3,88 (± 0,609) for Glossy ibis, 3,73 (± 0,703) for Squacco heron, 3,6 (± 0,985) for Cattle egret, 3,44 (± 0,639) for Purple heron and 2,8 (± 0,774) for Black-crowned Night heron. The breeding success are 79%, 75%, 71,5%, 70,6%, 70% and 68% for Purple heron, Squacco heron, Black-crowned Night heron, Little egret, Glossy ibis and Cattle egret, respectively. Long-term monitoring and study of the nest site characteristics and breeding parameters is an essential tool for conservation and management plans for colonial species. © EuroJournals Publishing, Inc. 2007.
