Nanjarayan Tank is a 440 acre reservoir in the outskirts of Tirupur town, near Koolipalayam, off Uthukkuli Road. It is officially known as “Koolipalayam Reservoir” or “Sarkar Periyapalayam Reservoir”. Going back in history, we come to know that this tank was built by a local king called “Nanjarayan”, over 400 years ago. Hence the tank has been renamed as Nanjarayan Tank in the recent past. This tank is a home for several inland and migratory birds for centuries. The water source is the Nallar River, flowing from the Avinashi Big Tank and few sewage canals, carrying the effluents and sewage from Tirupur town. Eventually the water level has never come down due to the above sources.
The flora and fauna of this tank attracts as many as 135 species of birds from all over. Inland birds like Spot-billed Pelicans, Painted Storks, Spoonbills, Black Headed Ibis, Darters, Grey Herons, Purple Herons, Intermediate Egrets, Little Egrets, Cattle Egrets, Indian Pond Herons, Little Heron, Black capped Night Herons, Cormorants, Spot-billed Ducks, Little Grebes, Black Winged Stilts, Common Moorhens, Common Coots, Purple Swamphens, White-breasted Waterhens, Common Snipes, Red-wattled Lapwings and Yellow Wattled lapwings are residing in the tank throughout the year.
It also brings in a huge number of species from other parts of the World during the winter. Starting from November, every year, various birds flock in to Nanjarayan Tank and spend their winter and leave back to their home by the end of March. Northern Shovelors, Northern Pintails, Garganey, Common Teals, Ruff, Marsh Sandpiper, Wood Sandpiper, Common Sandpiper, Greenshank, Redshank, Little Stint, Little Ringed Plover, Lesser Sandplover, Black-tailed Godwits, Green Sandpipers, Rosy Starlints, Yellow Wagtails and Citrine Wagtails come in huge numbers.
Apart from the above, the green cover around the Nanjarayan Tank serves as a home for birds like Blue Tailed Bee-eaters, Rufus Treepies, Koels, Coucals, Bay-backed Shrikes, Pied Kingfishers, Common Kingfishers, Whie-throated Kingfishers, Laughing Dove, Rock Pigeons, Eurasian Collared Dove, Rose ringed Parakeets, Brahmini Kites, Booted Eagles, Black Kites, Drongo, Pied Bushchats, Warblers, Munias, Barn Swallows, Swifts, Hoopoe, Spotted Owlets, Ashy Priniya, Pied Cuckoos and Indian Rollers.