Chapter 1. INTRODUCTIONMany species aggregate for feeding, perching, and nesting, activities that are widespread among waterfowl (Weins, 1992). Why animals form breeding colonies is a major unresolved question in evolutionary biology. The subject continues to generate lively debate (Danchin & Wagner 1997, Tella et al., 1998) and has been the subject of long-term studies (Hoogland 1995; Brown & Brown 1996; Danchin et al. 1998). One of the main questions is whether colonies form because of limited breeding habitat; with animals forced to nest together at the cost of nesting, or result from the social benefits of grouping (Foraging, reduced predation; Lack 1968; Alexander 1974; Hoogland & Sherman 1976; Wittenberger 1981). Nesting patterns in birds range from widely spaced solitary nests to densely populated colonies of hundreds of individuals. Colonial nesting occurs in 29 of 129 avian families (Lack, 1968). Colonial nesting is an important characteristic in the majority of members of the Pelicaniformes and Ciconiformes (Ali & Ripley, 1987, Burger, 1981). The nesting colonies of these birds which represent spatial and temporal groupings of nests are commonly called Heronries. Colonial waterbirds face significant threats to the long-term stability of their populations and habitats due to impacts such as the destruction of freshwater wetlands, destruction and degradation of coastal ecosystems, depletion of the forage base in freshwater, coastal and marine ecosystems, contaminants, sea level rise and various conflicts with human use of land and resources. For some species, these threats have led to a decline in numbers. In other cases, these disturbances have caused colonial waterbird species to become a nuisance... middle of article... Endangered lesser adjutant storks (Leptoptilous javanicus) are also breed in the Bhitarkanika Wildlife Sanctuary, which was recently identified as an Important Bird Area (IBA) of the country. The heronry is located on an island covered in mangrove vegetation. Improved feeding due to the presence of abundant feeding areas in and around the heronry in terms of wetlands and agricultural fields, reduced predation due to the distance from the nesting site, are believed to be the main factors governing the world's largest congregation of waterfowl. heronry. So far, there is no empirical ecological data on the heronry. It is therefore imperative to study the breeding biology of breeding birds, resource exploitation in terms of nesting material and food, nutritional requirements of breeding birds, changes in land use. pattern in feeding areas where applicable,