Study on Breeding Biology of Large (Egretta alba) and Median egret (Egretta intermedia) in Kerala, South India

Breeding in Egretta alba and Egretta intermedia coincide with the onset of south west monsoon. The present study is conducted in a temple yard in Pattambi, where the heronry initiates on the last week of May. Arrival of large egret triggers the building of nest by the other herons like median egret, little egret as well as little cormorant in the breeding site. They are colonial nesting species which build platform type of nests. Clutch size of large egret varies from 1-3 whereas in median egret it is 1-4. The mean incubation period Egretta alba and Egretta intermedia are 23.57 ±1.05 days and 24.88±0.73 days respectively. Hatching success of Egretta alba and Egretta intermedia was 84.09± 1.2 and 81.7± 1.3 respectively. Mean fledging success of Egretta alba and Egretta intermedia was 90.6± 0.72 and 91.4 ± 1.9 respectively. In large egret the last batch of fledgling left the nest by the first week of October whereas median egrets start nesting from July to last week of September. Offensive smell of rotten fish and excrement were the major causes for felling the nesting tree from their colony.