That islands are being built on the centuries-old artificial lake — which also happens to be the largest freshwater body in Puducherry — is old news. That it is being done to create a safe haven for migratory birds — about 20,000 of whom visit Oussudu lake every winter — is also a fairly well known fact. We take a deeper dive down into the plan of action drawn by Indigenous Biodiversity Foundation (IBF) and Aranyam Foundation, and take a look at the nuts and bolts of the island-building process.
“We are building a total of eight islands and seven smaller mounds, spread at gaps of about 100 metres from each other, as well as from the mainland, because human presence is a big hindrance to bird breeding,” says S Vimalraj, a conservator with IBF and one of the main minds in the four-people team behind the project. “The islands will be 10 feet high, and their area will range from 4,000 square feet to 20,000 square feet. The mounds, on the other hand, will be just three to five feet high, and anywhere between 500 square feet and 2,000 square feet across.”
The heights and sizes are decided based on two main factors: the water levels in different parts of the lake, and the varying needs of the birds that frequent it. For instance, according to Raphaël Mathevet, scientist and head of the Department of Ecology at the French Institute of Pondicherry, “Oussudu is a mix of reed beds, wetlands and huge stretches of water: it is singular in that way. Pelicans need huge areas with a lot of fish; waders need mudflats; ducks prefer large water bodies.”
PUDUCHERRY, 15/07/2019: (TO GO ALONG WITH STORY BY S. PRASAD) Members of Indigenous Biodiversity Foundation, a non profit organisation engaged in creating artificial islets on the dry bed of the Oussudu Lake to attract migratory birds. Photo: S.S. Kumar / The Hindu
Mathevet has a keen interest in how this project turns out, not only from an academic point of view, but also as one of the people who conduct the annual bird census in the area every February. The “conservation value” of the lake is something he cites often in conversation. “The space attracts ducks, waders, flamingoes and pelicans. In the 1980s especially, there were a lot of wintering ducks, coots and cormorants. But there has been a shift in the community of species in 2017, 2018 and 2019. There are fewer sightings of ducks, teals and the black-headed ibis, while storks, spot-billed pelicans, glossy ibis and black-tailed godwits and other waders have risen in number,” he says.
The shrubs, reeds and trees available at the lake also matter to the visiting birds. Which is why Vimalraj and team — comprising K Raman, Prabhu N Ponmudi and N Ritesh — have also drawn up a list of what they will be planting at which island. “When the locals were clearing the lake of invasive shrubs, they also ended up clearing a main breeding shrub by mistake, as well as vetiver grass which the ducks prefer,” he says, reeling off a list of eight species of flora the team has begun planting.
PUDUCHERRY, 03/06/2019: (STANDALONE) A painted stork with its catch in the Oussudu Lake near Puducherry. Photo: S.S. Kumar / The Hindu
“There were a few natural islands on the lake already, a few years ago, as well as a semi-artificial one that grew by accident about two years ago, because of the dispersal of seeds. That island is actually where I got the idea from,” he says, also admitting that the entire thing is still something of an experiment, though rooted in research and observation. There are little things that may or may not go wrong, but that will just have to be observed, points out Mathevet: “If it works, the lake will attract several thousand more birds than it currently does, and cause as much of a rise in bird droppings.” These droppings might act as pollutants [if one considers the lake a future source of drinking water], or they might act as fertilisers. The banks of the islands might influence fish breeding behaviour. None of these, he says, can quite be predicted: they can only be observed when the changes start taking place.
Mathevet also echoes Vimalraj in his observation that, though Oussudu forms a comfortable stopover for many species on their migratory route, it remains a place that these birds “stop by for a while”, instead of settling down in for the winter. Perhaps now, they might change their mind.
