The long stretches of paddy fields in Hospet, Gangavathi, Bellary, Siruguppa and Sindhanur taluks in Bellary, Koppal and Raichur districts indicate the change that the Tungabhadra Dam brought to the lives and landscapes of the region. The dam, built across River Tungabhadra near the city of Hospet, is significant to Karnataka in many ways. While it created one of the biggest water reservoirs in the state, the majestic view of the dam also attracts tourists from near and afar.
The huge reservoir spread over 378 sq. kms gradually attracted migratory and resident aquatic fowl. The availability of abundant food sources such as different species of fish, insect larvae, crustaceans etc. ensured food security for the birds. Apart from more than 90 fish species, the reservoir is home to the Smooth-coated Otter, Mugger, and Asian Giant Soft-shelled Turtle. The small islands in the middle of the dam are ideal breeding grounds for birds. Thus, the reservoir is a biodiversity hotspot for faunal species.
Why was the Tungabhadra Dam (TB Dam) built?
River Tungabhadra, one of the main tributaries of River Krishna, has been the lifeline of this region since time immemorial. It is said that the rulers of Vijayanagara harnessed this water source by constructing over 12 small dams across the river, and supplied water to agricultural fields though 16 channels of 210 kms length. Till date, this ancient irrigation system is active in Hospet and Hampi regions.
But, droughts and floods were common in the vast dry zone of these eastern plains of the Deccan Plateau. While the civilisation along the river led a sustained life, people far from the river suffered droughts for centuries, as their only sources of water were lakes and wells, which dried during summers. The great famine that hit the region in the 1870s took a massive toll on the people of Deccan Plateau, which included Bellary, Koppal, and Raichur districts. Sir Arthur Cotton, a British officer, conceived the idea of constructing a dam to help improve the living conditions of people; the British may have believed that building a dam was more economical than undertaking famine relief measures. Arthur Cotton, who was also a reputed irrigation engineer, prepared a detailed plan of a dam across River Tungabhadra, along with its canals and irrigation systems, but the project did not start due to financial constraints.
Finally, a project report prepared in 1942 by the chief engineer of Madras Presidency, M.S.Thirumalai Iyengar, was accepted. The foundation stone for the dam, which was taken up as a joint venture, was laid on 28 February, 1945, by the prince of Berar (Nizam of Hyderabad) on the left side of the bank, and Sir Arthur Hope, the governor of Madras, on the right side. The dam became functional in 1953. Over 90 villages were shifted to make way for the water storage. The site is said to be ideal for the dam as it is supported by hills at either end, impacting the maximum possible area.
Important Bird Area (IBA)
In the beginning of winter, a huge congregation of birds is seen along the vast mud-banks that span hundreds of kilometres. Small islands and mudflats provide shelter to migratory birds. About 200 species of birds have been recorded in and around TB Dam reservoir, and more than 20,000 migratory birds are found in winter in the reservoir.
Some species occur in much greater numbers than their 1% population threshold, determined by Wetlands International (2012). For example, the 1% threshold of Little Cormorant is 2500, but sometimes more than 5000 are found. Similarly, the 1% population threshold of Bar-headed Goose is 560, but in the reservoir and surrounding areas, it is not unusual to see a few thousands of these birds. They mainly use the reservoir and islands for roosting, and forage in the surrounding crop fields. Other species found in much greater numbers than their 1% population threshold are Painted Stork, Asian Openbill, Woolly-necked Stork, Black-headed Ibis, Indian Black Ibis, Glossy Ibis, Northern Pintail, Greater Flamingo, and Black–tailed Godwit. On the basis of these facts, the Tungabhadra Reservoir is listed as an Important Bird Area (IBA) of India in the latest edition.
TB Dam’s other prominent resident birds are – Indian Spot-billed Duck, Lesser Whistling-duck, Comb Duck, Cotton Pygmy-goose, Indian Cormorant, Greater Cormorant, Grey Heron, Purple Heron, Brahminy Kite, Short-toed Snake-eagle, Small Pratincole, and Sykes’s Lark.
Among the long distance migratory species, we have the Bar-headed Goose, Ruddy Shelduck, Northern Pintail, Northern Shoveller, Eurasian Wigeon, Garganey, Whiskered Tern, Little Tern, Brown-headed Gull, Oriental Pratincole, Pacific Golden Plover, Spotted Redshank, Common Greenshank, Common Redshank, Marsh Sandpiper, Wood Sandpiper, Common Sandpiper, Black-tailed Godwit, Western Marsh Harrier, Pallid Harrier, Montagu’s Harrier, and Osprey.
Nests of the Red-necked Falcon have not been found, but they probably breed in the area as the habitat is quite suitable for them. In recent years, it is found that Painted Stork, Grey Heron, Purple Heron, Black-crowned Night Heron, Black-headed Ibis, Darter etc. nest in Babool trees (Acacia nilotica) in Ankasamudra Lake, on the backwaters of TB Dam.
During summer, as the water recedes, large areas of the backwater open up to create massive breeding grounds for local and migratory birds. It is very interesting to know that while the Black-winged Stilt gathers shells and lays eggs in wet mud-banks, the Indian Courser and Little Tern lay eggs in grassy landscapes. Little Ringed Plover, Kentish Plover, Yellow-wattled Lapwing, Red-wattled Lapwing, and Small Pratincole lay eggs amidst stony-dry places far from the bank. A summer breeding migrant, the Oriental Pratincole, lays eggs in black cotton soil. Little Tern, Chestnut-bellied Sandgrouse and Blue-tailed Bee-eater are some other species that breed in the different parts of the backwaters.
It is interesting to note that eggs of different breeding birds are highly camouflaged and very difficult to trace by untrained eyes. The chicks also bear the colours of their surroundings and are hard to find. For example, the feathers of the chicks of the Indian Courser look like dry straw or the grass of that location—pale yellow with black tips—which camouflage the chick from predators. Similarly, the chicks of Small Pratincole and lapwings look like the stones found in their habitats. Adding to this, all these chicks remain immobile and play dead when predators or humans approach them. The parent birds of pratincoles and lapwings also distract intruders by their ‘broken wing’ display.
As far as conservation statuses are concerned, the TB Dam area is host to birds classified as ‘Vulnerable’ as well as many listed as ‘Near Threatened’ by the IUCN. Over the period of sixty years of its existence, the backwaters of Tungabhadra Dam have remained a permanent paradise for local and migratory birds. In spite of disturbances such as the movement of cattle, people, vehicles, fishermen etc., the breeding of birds has sustained, and their populations continue to remain stable, which is heartening, and something beyond our imagination!