Foraging patterns and kleptoparasitism among three sympatric cormorants (Phalacrocorax spp.) from the Delhi region, North India
- 157 Downloads
Cormorants, described as ‘foot-propelled pursuit divers’, constitute an important component of aquatic food webs and exhibit unique foraging behaviour patterns, which can be properly understood through a comparative study. Since, after a foraging dive they surface to ingest the prey, the intensity of kleptoparasitic attacks on the surface can have a major impact upon the net energetic gain for each individual. Inspite of the fact that cormorants and their habitats are severely threatened in India, their foraging behaviour has not been adequately studied. Such considerations prompted us to undertake field studies on three sympatric cormorants (Phalacrocorax spp.) at 60 different sites in the Delhi region of North India, during 2004–2007. By means of video photography, some key foraging parameters including group size, prey size and patterns of kleptoparasitic attacks were quantified. Along a loose body size gradient, we observed significant differences among the three species with respect to not only their preference for wetland size but also prey size. The frequency of a kleptoparasitic attacks depended upon the group size and foraging behaviour of each species. It was observed that several foraging bouts were abruptly terminated due to human disturbances, mostly at sites lying outside the protected areas. This observation points towards the need to conserve small waterbodies in the countryside, currently threatened by pollution and urbanization, for the benefit of a variety of waterbirds including cormorants.
KeywordsPhalacrocorax Foraging behaviour Body size Prey size Group size Kleptoparasitism India
This study was made possible by funds made available to AJU from the University of Delhi’s scheme to ‘strengthen R & D Doctoral Research Programme by providing funds to university faculty’ and a Kushlan grant from the Waterbird Society. MM acknowledges the University Grants Commission, New Delhi for the award of a research fellowship. We wish to place on record our gratitude to officials of various forest departments and biodiversity parks who extended their support and cooperation during the course of this study. We thank two anonymous referees whose constructive comments were extremely useful in revising the manuscript.
- Ali, S. & S. D. Ripley, 1987. Compact Handbook of the Birds of India and Pakistan. Oxford University Press, Delhi.Google Scholar
- BirdLife International, 2001. Threatened Birds of Asia: The BirdLife International Red Data Book. BirdLife International, Cambridge.Google Scholar
- Butler, P. J. & D. R. Jones, 1997. The physiology of diving of birds and mammals. Physiological Review 77: 837–899.Google Scholar
- Ganguli, U., 1975. A Guide to the Birds of the Delhi Area. Indian Council of Agricultural Research, New Delhi.Google Scholar
- Google Earth, 2009. Google Earth Software. [Downloaded on 20 March 2009. http://earth.google.com].
- Islam, M. Z. & A. R. Rahmani, 2004. Important Birds Area in India: Priority Sites for Conservation. Bombay Natural History Society and BirdLife International, Mumbai and Cambridge, UK.Google Scholar
- Muir, G. B. F., 1916. Cormorant (Phalacrocorax carbo) and fishing eagle (Haliaëtus leucoryphus). Journal of Bombay Natural History Society 24: 598.Google Scholar
- Orta, J., 1992. Family Phalacrocoracidae (Cormorants). In del Hoyo, J., A. Elliott & J. Sargatal (eds), Handbook of the Birds of the World, Volume 1: Ostrich to Ducks Lynx Edicions. Barcelona, Spain: 326–353.Google Scholar
- Punta, G. E., J. R. C. Saravia & P. M. Yorio, 1993. The diet and foraging behaviour of two Patagonian Cormorants. Marine Ornithology 21: 27–36.Google Scholar
- Rodgers, A. W. & H. S. Panwar, 1988. Planning a protected area network in India 1. The Report, Wildlife Institute of India.Google Scholar
- Ross, R. K., 1976. Notes on the behavior of captive Great Cormorants. Wilson Bulletin 88: 143–145.Google Scholar
- Urfi, A. J., 1995. Wetlands of ornithological significance in the Delhi region. Oriental Bird Club Bulletin 22: 38–41.Google Scholar
- Urfi, A. J., 2003. The birds of Okhla barrage bird sanctuary, Delhi, India. Forktail 19: 39–50.Google Scholar
- Urfi, A. J. & M. Mahendiran, 2005. A review of cormorants in India and a note on the cormorant colonies in the heronries of the Delhi Zoo. Cormorant Research Group Bulletin 6: 39–43.Google Scholar
- Voslamber, B., M. Platteeuw & M. R. Van Eerden, 1995. Solitary foraging in sand pits by breeding cormorants Phalacrocorax carbo sinensis: does specialised knowledge about fishing sites and fish behaviour pay off? Ardea 83: 213–222.Google Scholar