Nesting ecology of colonial waterbirds at Bhitarkanika mangroves, Orissa

Abstract

Colonial nesting is an important feature among a majority of the members of Pelicaniformes and Ciconiiformes. The nesting colonies of these birds that represent spatial and temporal clumping of nests are popularly referred to as heronries. One of the largest heronries in India is located in the Bhitarkanika mangroves, along the east coast of India. Birds use five species of mangrove trees for nesting which include Excoecaria agallocha (Guan), Heritiera fomes (Bada Sundari), Cynometra iripa (Singada), Hibiscus tiliaceus (Bania), Tamarix troupii (Jagula) for nesting in the heronry. . The breeding birds in this mixed species colony are Asian Openbill, Great Egret, Intermediate Egret, Little Egret, Cattle Egret, Grey Heron, Purple Heron, Black-crowned Night Heron, Little Cormorant, Darter, and Black-headed Ibis. The heronry in Bhitarkanika is located in an island covered with mangrove vegetation. The availability of large number of nest trees in terms of the mangrove forest and foraging areas in terms of the wetlands inside the forest and the paddy fields surrounding the forest are believed to be the factors favouring such large congregation of breeding water birds in the heronry