Bird Migration

Recently I travelled to Tuticorin in Tamil nadu from Bangalore by bus.Enroute to Tuticorin from Madurai,I think it was somewhere near the Aruppokottai region (I am not sure),I saw lot of white birds perched atop trees found in road side ponds.In each tree top,they were in such large numbers,that even some of the trees looked in spotless white colour from a distance.I presumed thses birds were heading towards the Kunthakulam Bird Sanctuary in Tirunelveli district.Kunthakulam is a small village about 30 kms away from Tirunelveli.It is said many birds from Pakistan, Myanmar, Sri Lanka, USA, and Australia visit this small scenic village during January to April.The sight of these birds prompted me to wite this post about bird migration.During my college days I have visited the famous Vedanthangal Bird Sanctuary during the bird migration season.One can find Herons,siberian cranes,Open billed Stork, Spoonbill, Little Grebe, Black Winged Stilts, and some times Grey Pelicans and cuckoos.I don't remember the names of some other bird species.I still remember watching the migratory birds atop the trees in the huge vedanthangal lake,through the telescope fixed atop a tower. November to February is the ideal season to visit the sanctuary.Right from my student days 'bird migration' is something that fascinated me.It is quite interesting to note that these birds travel thousands of miles during the migration season.It is said that these long distance migration of birds are genetecally programmed as a response to the change in the length of time in a day.This happens due to the seasonal changes.But what used to surprise me is the navigational ability of these birds.It is said the birds can read mental maps and identify hibitats.It is also said birds use electromagnetic tools for navigation and identify their destinations.The timing of bird migration mostly depends on climatic changes.It is estimated that around 4000 species of birds migrate world over.Out of this 4000 species,over hundred species of migratory birds fly to India, during severe winter of their native habitat in search of feeding grounds. The wildlife sanctuaries of the country become their temporary habitat during the migratory season.Once the season is over they fly back to their resident habitat.Statistics suggest majority of the bird return to the same location in successive years.It is also said some bird use certain landmarks to find a destination from the height at which they are flying. This is akin to what the pilots do to manouver aircrafts while flying.Renganthittu near srirengapatnam in Karnataka ,Thettakkad and Kumarakom in Kerala are the other noted bird sanctuaries in South India.Apart from Vedanthangal and kunthakulam ,Point Calimere Wildlife Sanctuary in Tamil Nadu is another shelter to migratory birds.