Study Records 47 Bird Species at Nemmeli as Mamallan Dam Project Faces Environmental Scrutiny
New field survey identifies dozens of breeding bird species in the Kovalam–Nemmeli Coastal Wetland Complex, intensifying concerns over the ecological impact of Tamil Nadu’s proposed Mamallan freshwater reservoir.
A new ecological survey has documented 47 bird species breeding in the Kovalam–Nemmeli Coastal Wetland Complex near Chennai, adding fresh momentum to the environmental debate surrounding the proposed Mamallan freshwater reservoir project. The findings come as the project continues to face legal scrutiny before the southern bench of the National Green Tribunal (NGT) over its potential impact on fragile coastal ecosystems.
The survey, conducted by volunteer conservation collective Suzhal Arivom, found that the wetlands serve not only as an important wintering site for migratory birds but also as a crucial breeding habitat for resident species. Researchers documented 22 breeding species in the open saltpans and mudflats around Nemmeli, while another 25 species were recorded nesting in nearby wetland margins and mangrove patches around Kelambakkam.
Among the species confirmed to be breeding are the red-wattled lapwing, Kentish plover, black-winged stilt, grey francolin, oriental pratincole, red-necked falcon, and Indian pied starling. The survey also highlighted the presence of the great thick-knee, a Near Threatened species on the IUCN Red List that has reportedly bred at Nemmeli for at least five consecutive years, making the area one of its most significant known breeding strongholds in the region.
Conservationists argue that these findings were not adequately reflected in the project’s Rapid Environmental Impact Assessment (REIA). According to the researchers, the avifaunal survey for the REIA was conducted between July and November 2025, whereas the primary breeding season for many resident bird species occurs between February and June, potentially overlooking critical ecological activity.
The proposed Mamallan reservoir is intended to strengthen Chennai’s long-term freshwater security by storing surplus monsoon water. However, environmental groups fear that construction could alter the natural hydrology of the coastal wetlands, affecting saltpans, mudflats and estuarine habitats that support nesting and feeding birds throughout the year.
State authorities have defended the project, stating that environmental safeguards have been incorporated into its design. In an affidavit before the NGT, the Tamil Nadu Coastal Zone Management Authority (TNSCZMA) said mitigation measures include the creation of six artificial islands to provide alternative nesting and roosting sites, rejuvenation of the Buckingham Canal to maintain tidal exchange, and development of shallow peripheral wetlands to support feeding by wading birds.
Wildlife experts, however, remain unconvinced that engineered habitats can fully replace naturally evolved coastal ecosystems. They argue that ground-nesting birds depend on extensive open saltpans and mudflats whose ecological characteristics cannot easily be replicated through artificial interventions.
The latest survey adds significant scientific evidence to the ongoing environmental assessment of the Mamallan reservoir project. As legal proceedings continue, the documented biodiversity at Nemmeli is expected to play a central role in determining how infrastructure development can be balanced with the conservation of one of Tamil Nadu’s most ecologically valuable coastal wetlands.
