India, Oct. 9 -- Reports from Chilika this week say its winged migratory guests have already begun arriving in the first weeks of October.

The Odisha Forest Department has intensified patrolling, 22 temporary bird-protection camps are in operation, and northern pintails, Eurasian wigeons, gadwalls, shovelers, glossy ibises and several other species are already being spotted around the lake and Nalabana. For many newspapers, this is a feel-good winter story.

For anyone who has watched Chilika for three or four decades, however, it is also an ecological signal worth watching carefully.

We must be cautious here. October arrival is not entirely new. Historical reports show migratory birds reaching Chilika in the second half of October, and...