Come March, and Vairamoni, an islet formed on the Idukki reservoir deep inside the Idukki Wildlife Sanctuary, bustles with activity. With no human intervention in sight, Indian river terns turn up in large numbers, making the islet a haven for laying eggs. On the sand bed, two to three eggs are laid in small pits. The islet resonates with the chirping of hundreds of birds till May when they fly away with the young ones.
Only through boat
Vairamoni was once said to be inhabited by tribespeople who were relocated prior to the commissioning of the Idukki dam. Now, the islet is accessible only through boat and under the control of Forest Department. The undisturbed ambience of Vairamoni, one of the biggest islets in the reservoir, makes it a seasonal habitat for breeding of river tern ( Sterna auratantic). The bird feeds on freshwater fish and aquatic insects. It is identified by its black cap, yellow bill, and reddish legs. The eggs are of greenish-grey colour and blotched, said an official of the Forest Department.
Rain, a damper
At times, heavy rainfall harms the eggs and chicks. If they are left intact, a large number of hatchlings fly away with the mother birds by the end of May and silence descends on the islet again.
Declining population
The officials of the Idukki Wildlife Sanctuary take care to provide an undisturbed ambience for the hatching of eggs. The birds make it a colony for collective breeding. Recent data on river tern say its number is declining due to pollution in habitats. However, the Idukki reservoir provides a favourable condition in terms of clean water and availability of feed. The official said they usually monitored the birds’ activities from boats to avoid disturbing them. This, time water in the reservoir has not receded from the islet as much as in the past. However, the river terns have made their presence felt.
