Information on heronries in India mainly concerns a few regional studies (Mahbal, 1990, Nagulu and Rao, 1983, Naik et al., 1991, Naik and Parasharya , 1987, Parasharya and Naik, 1990, Santharam and Menon, 1991, Sharatchandra 1980, Singh and Sodhi, 1986), several site-specific studies (Chaudhuri and Chakrabarti, 1973, Datta and Pal, 1990, 1993; Gee, 1960, Nagulu, 1983, Neelakanatan, 1949, Neginhal, 1983, Paulraj, 1984, Ragunatha, 1993, Ragunatha et al., 1992, Sanjay 1993, Subramanya et al., 1991, Subramanya and Manu, 1996, Urfi 1989c,, 1990, 1993a , and Manu, 1996, Urfi 1989c,, 1990, 1993a,, and Manu, 1996 b; Vijayan, 1991) and a number of site surveys (Abdulali, 1962, Ali, 1960, Baker, 1935, Barnes, 1886, 1891, Barooah, 1991, Bates and Lowther, 1952, Badshah, 1963, Betham, 1904, Bingham, 1876, Bhat et al., 1991, Bolster, 1923, Chhaya, 1980, Daniel, 1980, Hume, 1881, Jamgaonkar et al ., 1994, Packard, 1903, Urfi 1992, Uttaman, 1990, Wilkinson, 1961). Very few studies have been carried out so far on colonial waterbirds of Indian mangroves. Mukerjee (1969) studied the feeding habits of a few selected water birds in the mangrove forests of the Sunderbans. Prasad (1992) reports a large inaccessible heronry in the Krishna mangroves. Subramnaya (1996) updated existing information on the status, distribution and conservation of Indian heronries.2.2 Breeding biology: Colonial breeding, i.e. breeding in densely distributed territories that do not contain any resources other than nesting sites (Perrins and Birkhead, 1983), is an unexplained situation. form of social reproduction that occurs in many vertebrates. (Wittenberger et al., 1985, Brown et al., 1990). Coloniality is an evolutionary puzzle because individuals apparently pay fitness costs to reproduce at high density. The costs identified are increased transmission of parasites and diseases (Moller, 1987), cuckolding (Moller et al., 1993), increased intraspecific competition for food and mates (Moller, 1987), cannibalism and infanticide (Wittenberger et al., 1985 and Moller, 1987). Despite the costs, many hypotheses have been proposed to explain how colonial breeding can benefit the individual, but most of them still have little support and none seem convincing (Wittenberger et al., 1985 and Siegel -causey et al., 1990). . Until the late 1980s, most discussions of the evolution of coloniality were dominated by the twin hypothetical benefits of improved foraging (Barta, 1995) and reduced predation (Wittenberger and al., 1985, Anderson et al., 1993 and Clode, 1993). ). By the end of this period, studies concluded that avian coloniality is not a simple or unitary phenomenon and that not all breeding colonies are adaptive for the same reason..