A first-of-its kind census conducted in the wetlands and birds sanctuaries in Tiruvarur, Thanjavur and Perambalur districts by the Forest department and students and environmentalists from various colleges has revealed a high diversity among the birds which congregate. According to Mr. Shekhar Kumar Niraj, Wildlife Warden and District Forest Officer, Nagapattinam, who organised the census in February, the objective of the exercise was to monitor birds' population to know the ecological status of the four wetlands and to create awareness among the people about biodiversity. The bird population was the best indicator of the habitat.