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Site description (2004 baseline)
Chilika Lake is an estuarine lagoon, shallow throughout its spread of 1,16,500 ha. It is the largest brackish water wetland in India (Kar and Sahu 1993). The Government of India notified Chilika Lake as a Ramsar site in 1981. The pear-shaped lake is connected to the Bay of Bengal at its northeast end and is subject to minor tidal fluctuations. It receives water from rivers Daya and Bhargavi, and several small streams. It is the largest wintering ground for migratory waterfowl in India (Anon. 2000). According to historical evidence, Chilika Lake was part of the Bay of Bengal about 6,000 years ago. Merchant ships used to travel from Chilika to South East Asia (Trisal and Chauhan 1998). Over a period of time, a sand spit barrier formed due to the littoral drift of the sea, as well as silt deposits carried by adjoining rivers into the wetland, separating it from the Bay of Bengal. Several islands are located in the lagoon covering an area of 22,300 ha. The Nalabana Island of the Chilika Lake was declared as a bird sanctuary in 1987. It has an area of 1,553 ha. Nalabana literally means “forest of reeds”. It is covered with aquatic plants, predominant species being Phragmites karka. During monsoon, Nalabana is entirely under water, with only reeds and watchtower visible. With the onset of summer the island gradually emerges. The major flora comprises of aquatic macrophytes such as Potamogeton pectinatus, Najas faveolata, N. graminea, Halophila ovalis, Ruppia maritima, Phragmites karka, Scirpus littoralis, Cyperus sp. and Salicornia brachiata. The algal forms include Chaetomorpha linum, Enteromorpha intestinalis, Oscillatoria laetevineus, Cladophora glomerata, Ulva lactuca; and the less common Gracillaria verrucosa.

Key biodiversity

AVIFAUNA: Chilika Lake in general and Nalabana area in particular are among the most important waterfowl habitats in India. The total number of waterfowl in Chilika is close to 8,00,000 birds. Of the 211 species of birds recorded in Chilika and its environs, 121 species were reported from Nalabana. Seven Vulnerable species, and many Near Threatened species are found. In January 2003, more than 4,50,000 birds were counted on Nalabana Island, and more than 2,40,000 birds were counted in the northern sector from Kalupadaghat to Teenmuhani area. Very large numbers of birds were also observed in the Kansari River and Gangadharpur area (Sana Nairi village). Similarly, the unapproachable areas in the southern sector near Taltaola, Rambha, Naupada and outer-channel Jahnikuda provide refuge to more than 1,70,000 ducks and waders. It is estimated that Chilika Lake supported over 8,00,000 birds during the 2002- 2003 winter season (Balachandran et al. 2003). Large numbers of birds such as the Pintail Anas acuta (80,000), Garganey Anas querquedula, Black-tailed Godwit Limosa limosa (48,000), Gadwall Anas strepera (1,00,000) Eurasian Wigeon Anas penelope (40,000) Brown-headed Gull Larus brunnicephalus (20,000), and the marine terns (Large Crested Sterna bergii and Lesser Crested Sterna bengalensis) congregate on and around the island at dusk for roosting, and most of them depart in the morning. Over 1,000 Bar-headed Geese Anser indicus spend the winter at Nalabana every year. During 3 years of monitoring the maximum wader population (1,44,000) was recorded in January 2003. The rare Asian Dowitcher Limnodromus semipalmatus was seen in small numbers (10-15) and a total of five individuals were also ringed between 2002 and 2003. Large congregations (>1000) of Lesser Whistling Duck Dendrocygna javanicus were seen during January 2003. Over 5,000 Brahminy Shelducks Tadorna ferruginea were observed between Satapada (outer-channel area) and Nalabana. The globally threatened Pallas’s Fish-Eagle Haliaeetus leucoryphus was regularly sighted, solitarily or in pairs in Nalabana from December to March. Among other threatened species of Chilika Lake, between 175 to 300 Spot-billed Pelican were seen. Large breeding colonies of terns, namely the River Tern, Gullbilled Tern and Little Tern Sterna albifrons, along with the waders such as Black-winged Stilt Himantopus himantopus were recorded at Nalabana Island. The majority of nests were found in the middle of the island. Among the 1,032 nests noted in 2002, 540 and 323 respectively belonged to River Tern and Gull-billed Tern. The other two wader species breeding at Nalabana are Oriental Pratincole Glareola maldivarum and Kentish Plover Charadrius alexandrinus (Balachandran et al. 2002a). Many waders and ducks occur in much greater numbers than their 1% population threshold determined by Wetlands International (2002). For some species such as the Spoon-billed Sandpiper and Asian Dowitchers, this site is extremely important in India.

OTHER KEY FAUNA: Chilika Lake hosts 158 types of fish and prawn species. Fish include both marine and estuarine species. Penaeus indicus and Penaeus monodon are commercially important prawns. The sand crab Scylla serrata is the most abundant commercial crab of Chilika.

A remnant population of the highly endangered Irrawady Dolphin Orcaella brevirostris occurs only in Chilika in India.

Acknowledgements
Key contributors: S. Balachandran, Biswajit Mohanty and Ajit Patnaik.

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Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Nalabana Bird Sanctuary (Chilika Lake) (India). Downloaded from https://datazone.birdlife.org/site/factsheet/nalabana-bird-sanctuary-(chilika-lake)-iba-india on 22/12/2024.