River terns at summer rain’s mercy

Giji K. Raman
Kattappana,  
The Hindu, April 26, 2015

This summer is unlikely to add much to the population of Indian river tern ( Stema auratia ), a common bird species on the islet of Vairamani. The islet, a natural habitat of the bird, is strewn with eggs and dead chicks. Heavy summer rain is believed to have caused the damage.

Vairamani is accessible only by boat and is situated deep inside a sanctuary. It is considered the largest breeding place of the bird, which lays eggs on sand and hatches them if undisturbed by human or other intervention.

The breeding season of river tern is from March to May. By March, the birds would arrive there and the islet would soon have hundreds of eggs, each pit having one to four. Ornithologist R. Sugathan says the eggs need a particular temperature for a particular duration to hatch. If there are winds, the brooding birds could fly away, and the eggs would not hatch. Mr. Sugathan says that many factors, including climate change, result in advancing of the breeding season. There are chances of a second brooding by a bird, depending on the availability of food in the area. Forest Department officials are keen on protecting the habitat from outside intervention. Assistant Wildlife Warden G. Jayachandran says the breeding is being monitored.

The death toll of chicks this year is the highest, he says. It could also see a drop in the number of arrivals. Heavy rain could be a reason for the chicks’ death as they lie in the open without any natural protection.