Shrinking wetlands leave annual fliers high and dry

Every winter, millions of nature’s flying visitors offer a breathtaking visual treat along India’s wetlands and mudflats. These migratory birds fly thousands of kilometres to escape the harsh winters of their native habitat and bask in the warmth of India.

However, the once vibrant spectacle of avian migration is facing disruption due to human interference and dwindling wetlands. India’s wetlands are vital ecosystems for a myriad of plant and animal species. But unfortunately, they are shrinking at an alarming rate.

According to Wetlands International South Asia (WISA), India has lost nearly one-third of its natural wetlands to urbanisation, agricultural expansion, and pollution over the last four decades. This directly impacts migratory birds because they rely on wetlands as crucial stopovers during their journeys. “The population density, richness of species and diversity of migratory shorebirds have declined over the years. Some of the major causes are degradation of habitat, pollution, shrinkage of their foraging or feeding ground along with the dwindling of wetlands,” says Jeganathan Pandiyan, an ornithologist and associate professor in Zoology and Wildlife Biology at AVC College (Autonomous), Mannam-pandal.

The Flyways

The three major Asian flyways include the West Pacific, East Asian Austra-lasian, and the Central Asian Flyway (CAF). India lies within the extensive CAF, serving as a migratory route for over 400 bird species. These birds breed in central Asian regions and migrate south to the Indian subcontinent during winter, ensuring access to warmer climates and ample food.

Dr Sathiya Selvam, head of Wetlands and Flyways programme at BNHS (Bombay Natural History Society) says, “Birds like black-winged stilts are biological indicators. If they are declining, it is an indicator of a potential issue or threat.”

Wetland Ecosystem

Beyond just serving as the stopover for migratory birds, wetlands offer food, shelter, and breeding grounds. These areas teem with aquatic life, providing an abundant food source for birds such as ducks, geese, and shorebirds. The shallow waters of wetlands are ideal for foraging, and the surrounding vegetation provides essential nesting sites.

Despite their ecological significance, wetlands in India are under severe threat due to urbanisation, agricultural expansion, pollution, and climate change. Rapid urban development and the conversion of wetlands for agriculture have led to the draining and degradation of these critical habitats. Pollution from industrial runoff and untreated sewage further exacerbates the problem, making the remaining wetlands inhospitable for both wildlife and migratory birds. Over the past four decades, the ‘queen wetland of Kashmir,’ Hokersar or Hokera, situated 12 km west of Srinagar city, has witnessed a reduction in its area by 5.75 sq.km. Other wetland ecosystems of Kashmir like Dal Lake, Anchar, Wular, Haigam, Shallabugh, and Narkara are also facing similar issues due to rapid urbanisation, pollution, and siltation.

“From the smallest bird little stint to curlew or pelican, fly for thousands of kilometres. Their main requirement is diet or the prey matter. The accumulation of metals or the availability of metals in the water birds is perhaps due to their prey matter.

The sources of the metals to the water birds are their prey or diet sources,” says Jeganathan.

Jeganathan says that urbanisation is a significant factor in the shrinkage of wetlands. “Most of the agricultural wetlands are converted into real estate in the southern part of India which is a big worry and a threat.”

The LULC (Land Use/Land Cover) classes have undergone marked changes in the past two decades on the east coast of southern India (Chennai to Kanyakumari, including Point Calimere Wildlife Sanctuary, Pichavar mangrove forest and Pulicat Lake). Around 8 sq.km. of vegetation, 14.2 sq.km of mudflats and 8.6 sq.km. of waterlogged areas have been transformed for agricultural use. “The energy sector is a major concern for the shrinking of wetlands or mudflats. Construction of big plants require minimal permission and less paperwork when building on free land as opposed to private lands that require heavy documentation and formalities,” says Dr Selvam. He further added that blades of wind turbines, transmission lines, privatisation of energy distribution, are some of the other factors that harm the migration of birds.

Deadly Impact

The decline of wetlands has affected various migratory bird species — Siberian Crane, Bar-headed Goose, and various species of ducks that rely on wetlands for their survival. These birds face challenges in finding suitable places to rest, feed, and breed.

AWC reports a significant decline in long-distance water bird migration due to global climate change and shrinking wetlands. In autumn 2023, Najafgarh Jheel, Sultanpur NP, Okhla Bird Sanctuary, and Dhanauri village wetland observed fewer water birds. Rapid urban development has led to over 50% shrinkage of Najafgarh Lake in Delhi and Pallikaranai in Chennai, causing a scarcity of water sources.

Need of the hour

Migratory bird decline in India underscores the urgent need to protect wetlands. Conservation must be prioritized to reverse damage. Jeganathan urges awareness, regulated tourism, and eco-friendly practices to prevent mudflats from becoming garbage. Monitoring fisheries and considering mangrove afforestation are essential. Dr. Selvam emphasizes individual responsibility.

BIRD’S-EYE VIEW  

• India lost nearly 30% of its wetlands in the last 30 years
• Migratory birds from Eurasia and the Arctic have declined by 50%
• India serves as a migratory route for over 400 bird species
• Total wetlands in India are 1285 — 75 Ramsar wetlands, 115 significant wetlands and 1095 other wetlands
• Curlew sandpipers have declined over the years
• Rapid decline in Spot-Billed Pelicans in the last three years (SOIB report 2023)
• Shorebirds that breed in the Arctic have been declined by 80%
• Migratory species endemic to the Western Ghats and Sri Lanka have been affected badly

Natural Sewage Treatment

Kolkata’s wetlands process 60% of the city’s sewage, saving over $64 million annually, as per a 2017 University of Calcutta study. Each day, 910 million litres of nutrient-rich sewage enter the wetland, sustaining a network of around 250 ponds covered with hyacinths.

“Birds like black-winged stilts are biological indicators. If they are declining, it is an indicator of a potential issue or threat.” — Dr Sathiya Selvam, Head of Wetlands and Flyways programme, BNHS