The Status, Distribution and Conservation of Indian Heronries
2819 Words12 Pages
The information on heronries in India pertains mainly to 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, 1992, 1993a,b; Vijayan, 1991) and a number of site records (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 so far carried out on the colonial water birds of Indian mangroves. Mukerjee (1969) studied the feeding habits of few selected water birds in the mangrove forests of the sunderbans. Prasad (1992) reports about a large inaccessible heronry in the Krishna mangroves. Subramnaya (1996) updated the existing information on the status, distribution and conservation of Indian heronries.
2.2 Breeding Biology:
Colonial breeding i.e., breeding among densely distributed territories that contain no resource other than nest sites (Perrins and Birkhead, 1983) is an unexplained 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 breed in high densities. Identified costs are increased transmission of parasites and diseases (Moller, 1987), cuckoldry (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 may benefit the individual, but there is still little support for most of them and none appears compelling (Wittenberger et al., 1985 and Siegel- causey et al., 1990). Until the end of the 1980s, most discussions on how coloniality evolved were dominated by the two hypothetical advantages of enhanced food finding (Barta, 1995) and reduced predation (Wittenberger et al., 1985, Anderson et al., 1993 and Clode, 1993). By the end of that period, reviews concluded that avian coloniality is not a simple or unitary phenomenon and that not all breeding colonies are adaptive for the same reason.