River terns fly back home leaving Vairamani deserted

Giji K. Raman
IDUKKI, 
The Hindu, June 10, 2015 

Vairamani islet, the largest nesting place of Indian river terns (sterna aurantia) inside the Idukki Wildlife Sanctuary wears a deserted look after the migratory season.

While ornithologists hoped for a second window for brooding, the unexpected heavy rains and winds played a spoilsport. During this brooding season (from March to May) large number of chicks was found dead and unhatched eggs dotted the islet. Hundreds of river terns turned up this season to lay eggs on the sand as the waters of the Idukki reservoir waned. But many eggs did not hatch and chicks were found dead. According to ornithologist R. Sugathan, the eggs need a particular duration for brooding and if there is wind, the birds would fly away leaving the eggs unhatched.

“There were heavy rains and winds which resulted in the large mortality rate of the chicks,” said the official.

Ornithologists were expecting a second brooding which is possible if food is readily available. Fresh water fish is the staple of river terns and the islet is undisturbed from human intervention and predators including the snakes. The reservoir provides the feeding ground for the brooding birds that usually fly away after the season. According to Assistant Wildlife Warden G. Jayachandran there is a plan to document the seasonal birds in the sanctuary which has been identified as a major habitat for resident birds. He said that climate changes and human intervention could result in poor availability of local fish varieties in the reservoir making an impact on the arrival of river terns in future.