Years ago, at the Perumbakkam wetland, naturalist K.V.R.K. Thirunaranan found pheasant-tailed jacanas building nests on scarps of floating polysterene material.
These discarded material had taken the place of floating vegetation towards which these birds have an affinity. Besides providing a stage for them to enact nature’s magic of regeneration, floating vegetation help these birds forage for food. As a wader, the pheasant-tailed jacanas look for food standing in shallow water. When the water runs deep, floating vegetation such as water lilies prove more useful. In these parts, pheasant-tailed jacanas trotting around on broad and flat leaves of water lilies is a common sight. Birdwatchers have given it a moniker — lily-trotter.
So, when the perumbakkam wetland, which not long ago would be drowned in the full-throated mews of phesant-tailed jacanas, does not seem to be attracting these birds in as many numbers as before, the first thing one looks for is signs of floating vegetation.
Now, the wetland doesn't have much floating vegetation, especially water lilies, that suit pheasant-tailed jacanas. There is duckweed, plenty of it, but this is obviously not the kind of floating vegetation that help jacanas.
The Sholinganallur lake located a short distance away, supports a population of pheasant-tailed jacanas, probably because there is water hyacinth, certainly not an aquatic plant one would want in any waterbody. It’s an invasive aquatic weed that can disturb the biodiversity balance in a waterbody or waterway.
D. Narasimhan, member of Tamil Nadu Biodiversity Board, says: “When the water is not clean, native floating vegetation, which includes water lilies, don’t thrive. In such a situation, invasive alien aquatic plant species such as the water hyacinth can grow wildly and take over a waterbody.”
Fortunately, in the Perumbakkam wetland, water hyacinth have not made an appearance — probably, not yet.
“In our parts, pheasant-tailed jacanas serve as a barometer to assess the health of a wetland. Lack of floating vegetation can be a strong reason for dwindling jacana presence in a wetland, but not the only reason. For, pheasant-tailed jacanas are drawn to grasses as well. At the Perumbakkam wetland, there have been times when pheasant-tails streaking out of grasses would be an usual sight. The wetland still has grasses. So, there could be other reasons at play," says Thirunaranan, founder of The Nature Trust.
Thirunaranan who is associated with the Conservation Authority of Pallikaranai Marsh Land, an initiative of the Forest Department, that seeks to preserve the Pallikaranai marsh, which includes the Perumakkam wetland, believes the latter does not receive as much water as before.
“Ever since a kucca road came up on the western side of the wetland, rainwater from the Perumbakkam hill does not flow into the wetland freely. The Forest Department has taken measures to get the rainwater in, which include laying pipes to carry water and making cuts in the kucca road. But water flow is still not as good as before," he says, adding that a thorough study of the wetland is needed.
