Rare sight of otter in Adyar River near city eco-park

Even in an urban landscape where buildings vastly outnumber trees, nature can still spring a surprise, as it did recently with the sighting of a smooth-coated otter in the Adyar River.

The sighting was made by birdwatcher Indou Theagarajan on December 28 at the Tholkappia Poonga. For Ms. Theagarajan, who has recorded as many as 70 bird species in the eco-park, the otter sighting came as a pleasant surprise.

Ms. Theagarajan was a regular visitor to Tholkappia Poonga.

‘Positive sign’

A regular visitor to Tholkappia Poonga, Ms. Theagarajan said, “I usually carry my binoculars for birdwatching most mornings. I was standing on one of the recently built platforms when I heard a sniffing sound from the water. At first, I thought it was a dog nearby, but when I looked more closely, I could see very clearly it was an otter. It was close to the platform, almost at the edge of the river.”

Naturalist Yuvan Aves said the sighting was a positive sign, and in the last couple of months there have been records of bird species being seen here after a long gap. He attributed this to the dredging of the river carried out for flood mitigation. The Adyar estuary has become the second hotspot on eBird, a citizen science birding platform, in recent months, he said.

“It is safe to say this is the effect of a trophic cascade,” Mr. Yuvan said, adding that the health of the benthic substrate is crucial for aquatic species and plankton production. When the river is heavily polluted, as the Adyar often has been with sludge, sewage, and other pollutants, it negatively impacts the ecosystem.

Water condition

Otters are said to keep a check on the population of other aquatic species and signify clean rivers that are free of pollutants.

Recent sightings of otters and birds such as oystercatcher, terek sandpiper, red-billed tropicbird, mongolian short-toed lark, isabelline wheatear, Saunders’s tern, indicate that improved river management can create a suitable environment for wildlife.

‘More otters’

Ecologist Albert Peter, who has worked extensively on otters in the Cauvery and Tamiraparani rivers, said smooth-coated otters, which are classified ‘vulnerable’ in the IUCN Red List, usually live in groups ranging from three to 15 individuals, suggesting there may be more otters in the Adyar River. “Otters are extremely good indicators of a healthy river system,” he said, adding their presence shows certain stretches of the river are now in good condition.