Round a dozen species of terns come to the town’s coast through the migratory season, and sustained monitoring of those birds can throw up recent info about their habitat necessities
Terns usually are not troublesome to trace. With a roosting sample that ticks to the tidal clock, they could nevertheless come throughout as placing in a barely irregular look.
So, here’s a tern-watching tip: Observe the low tide, discover the tern. It’s a tip Chennai nature lovers would do effectively to recollect: Round a dozen tern species hit its coast through the migratory season.
Ornithologist V. Santharam unravels this sample.
“Individuals are inclined to see these birds (terns) extra after they go on pelagic journeys, or in coastal areas the place these birds come to roost. Throughout low tide, terns roost on the sand banks and when the water stage rises, they fly away. They could exit within the evening, relying on the tidal motion. They aren’t strictly diurnal, and their actions are based mostly on the ebb and move of tides.”
Whereas conceding that waders additionally sync their roosting behaviour with the tidal motion, Santharam spells out the distinction: “Normally, terns roost on the mudflats throughout low tide, and waders throughout excessive tide. Waders normally want shallow open mudflats to feed on, and so with excessive tide, your complete space being lined with water and solely small components staying uncovered, these birds are left with little alternative to feed. So, waders would quite go and ‘relaxation the excessive tide’ out. In distinction, terns roost when there’s low tide, because it offers them sufficient place to park themselves on; and so they go into the ocean throughout excessive tide. As with many different issues about terns, even this one must be studied.”
The excessive flier
Among the many placing bodily options of terns is how they appear aerodynamically-enhanced. Comparisons are certainly odious. However they’re additionally one of the best guess in bringing uniqueness into the sunshine of unmistakable information.
Standing, a gull might seem heavier; and a tern, higher stream-lined. The latter is one thing of a Polaris Slingshot. A 3-wheeled bike, the Slingshot tapers off finely, as does a tern. Parked, it seems to be prepared for take-off.
Santharam underlines how terns are constructed for long-distance flying. One of many easily-recalled faces of long-distance migration is that of a tern. The Arctic Tern does an not possible Arctic-to-Antarctic annual “flyathon”.
The Caspian Tern seen round Chennai’s coastal sections through the migratory season can be an icon of long-distance migratory flying.
As soon as right here, the migratory Caspian Tern is aware of how one can make itself at dwelling, even discovered a bit inland in coastal marshlands.
Birdwatchers in these components wouldn’t be shocked to return upon congregations of Caspian Terns within the Perumbakkam wetland.
“Perumbakkam might be thought-about a part of the coastal marshlands. ‘Coastal’ would come with waterbodies which might be inside three to 4 kilometres from the seashore. However, through the migratory season, discovering them in waterbodies removed from the coast could also be troublesome,” factors out Santharam.
The appointed time
The White-winged Tern is among the many comparatively rarer migratory terns to sight across the Chennai coast.
“The White-winged tern is a passage migrant. It comes round this time — March and April, on reverse migration, when one can discover it alongside the Chennai coast, on coastal sections like Sholinganallur. It comes just for a brief interval. Within the non-breeding season, it may be confused with the Whiskered Tern. Throughout the breeding season, its plumage with its white wing makes it strikingly distinct. The following two weeks is the time to search for them,” says Santharam, including that in this slim window, massive numbers of White-winged Terns might be sighted. So, a White-winged Tern sighting is sure to occur in Chennai if you already know the when of it.
As an instance, birder Sundaravel Palanivelu is accustomed to assembly up with hordes of White-winged Terns in March-April round Sholinganallur-Perumbakkam space.
On the morning of March 20, Sundaravelu Palanivelu witnessed “a murmuration of round 200 White-winged Terns, flying over the Perumbakkam Wetland.”
The terns seen round Chennai are visiting migrants. Santharam nevertheless underlines that some species might be breeding round Sri Lanka and in locations on the South Indian Coast.
“The Higher Crested Tern (a winter migrant in Chennai) breeds round Sri Lanka and doubtless even round Rameswaram. They’re additionally recognized to be breeding off the West Coast. I’ve seen Higher Crested Terns in Lakshwadeep, however not breeding,” he says. “Throughout the migratory season, Level Calimere can be the place to identify each Higher and Lesser Crested Terns, as additionally Caspian Terns.” Amidst abounding information about chook distribution and behavior resulting from know-how and residents’ science, birds nonetheless handle to fly beneath the radar, maintaining components of their lives couched in a thriller.
“Typically, I’ve seen Caspian Terns across the Chennai Coast after April and Could and so they most likely breed off the Sri Lankan coast.” And on the Widespread Tern, Santharam makes this remark: “The Widespread Tern is understood to breed on the coast of Sri Lanka, however in Chennai it’s a winter migrant. It’s doable that it’s breeding in undisturbed locations alongside South Tamil Nadu, most likely round Mandapam.”
On how birds seldom stop to spring a shock, he factors out that Widespread Tern breeding has been reported from Ladakh.
Extra research required
Santharam highlights the truth that terns might be higher studied, and present research, particularly of wintering terns, are skinny on the bottom. He attracts consideration to neighbouring Sri Lanka: Exemplary efforts over the past decade spotlighting terns in Sri Lanka have proven these birds to be breeding in better numbers than beforehand believed. “Round a dozen species of terns come to Chennai through the migratoey season. Common monitoring can throw up attention-grabbing discoveries about their habits and habitat necessities.”
( ‘Migrant Watch’ is a weekly column about birds seen in Chennai through the migratory season)