The wetland of Koshi Tappu is the major international staging point for migratory wader, waterfowls and the birds of prey in Nepal. The area is the largest expanse of wetland in Nepal and holds rich variety of marsh birds. It is also of interest for some birds typical of dry grassland and shrubs.

The Koshi River is the biggest river of Nepal and is harnessed by embankments in the east and west of the river and a kilometer long barrage is built on the southern end. Extensive area of marshes, reed beds and sandbanks flank the river north of the barrage. During the monsoon there are large expanse of open water formed when the marshes flood. In winter the water levels are low, the marshes dry out to leave pools and streams, and large sandbanks appear along the river. Koshi Tappu Wildlife Reserve was established in 1976 and covers and area of 175-sq. km. Due to its international importance for the conservation of waders and waterfowls it has been accorded Ramsar Site by the Wetlands Convention in 1987.

The Koshi Barrage lies in the East West Highway and the KTWR Headquarters lies at Kusaha, 18 km from the barrage and only 2.5 km for the Jamuwa point of East West Highway. There are day and night bus services to reach Koshi Tappu from Kathmandu, one should stop at Jamuwa or Lauki Bus Stop. It is eleven hours drive from Kathmandu to reach Koshi, two hours from Kakarvitta Border and only one hour from Biratnagar Airport. There are number of daily flights to Biratnagar from Kathmandu. At least three days of stay is required to do birding in Koshi Tappu. Additional day is required to d birding in the Chatara-Dharan Forest. One can extend to do birding in the Mai Valley-Hangetham or Ilam - Sunischare that will require additional five days

The best time to visit Koshi is from October till May. Most of the site is easily reached by vehicles, boats, and bicycles and on foot. The best sites for bird-watching is between the river, grassland, bushes and marshes along the eastern embankments from Haripur to Madhuban. The barrage and the wetlands nearby it, the Pink tower is also good for bird-watching. Rare mammals occurring are Gangetic Dolphins, Wild Water Buffalo, Smooth Coated Otters, Fishing Cats, Nilgai Antelope, Hog Deer etc.

Specialties:

Bengal and Lesser Florican, Indian Courser, Hodgson's Bushchat can be found north of the Pink Tower. In the barrage Little Pratincole, Indian Skimmer, waders, gulls, terns etc can be seen.

One of the best times to visit this site is in February and early March when the main wildfowl passage takes place. In mid February a peak of over 50,000 ducks, mainly Northern Pintail have been estimated. A total of 25 wildfowl species have been recorded including regular sightings of Bar-headed Goose, Comb Duck, Cotton Pygmy Goose, Falcated Duck, Red-crested Pochard. Wader passage also takes place during this period although it also extends into mid May. Pacific Golden Plover, Temmincks Stint, Pintail Snipe, and Marsh Sandpiper occur annually. In additions small numbers of gull and terns can be seen both wintering and on passage. These include Great Black-headed and Brown-headed Gulls, Gull-billed, Caspian and Whiskered Terns.

It is also a best site to watch for birds of prey includes Brahminy Kite, Pallas's Fish Eagle, White-tailed Eagle, Eurasian Black Vulture, Short-toed Eagle, Pallid and Pied Harriers, Greater-spotted, Steppe and Imperial Eagles, Peregrine and Red-necked Falcon.

Winter (regular) : Little Cormorants, Black Stork, Baillon's Crake, Spotted Bush Warbler, Paddyfield, Clamorous Reed, Dusky and Smoky Warblers and Black faced Buntings.

Winter Visitor (rare) : Fulvous Whistling Duck, Baer's Pochard, Grey-headed Lapwing, Chinese Bush Warbler, and Palla's Grasshopper and Black-browed Reed Warbler.

Spring (regular): Hoopoe, Rosy Pipit, Yellow, Citrine, and White Wagtails and Blue Throat

Spring (rare): Spot-billed Pelican, Lesser Sand Plover, and White-winged Black Tern, Oriental Pratincole, Yellow-wattled Lapwing, Indian Skimmer and Jerdon's Bushchat.

Summer (breeding) : Yellow and Cinnamon Bitterns, Watercock, Pheasant-tailed Jacana,

Resident (regular) : Cattle, Little, Intermediate and Large Egret, Black-crowned Night, Purple and Pond Heron, Asian Open-bill, Wooly-necked, Black-necked (regular breeding species), Greater Adjutant and Lesser Adjutant Storks, Lesser Whistling Duck, Spotbill, Swamp Francolin, Osprey, Red-necked Falcon, Ruddy-breasted Crake, Purple Gallinule, Bronze-winged Jacana, Great Stone Plover, River and Black-bellied Terns, Lesser Coucal, White-tailed Stonechat, Graceful and Yellow-bellied Prinia, Striated Marsh Warbler, Black-breasted and Streaked Weavers and Red Avadavat, Yellow legged button-quail, Orange-breasted Green Pigeon, Brown Hawk Owl, Indian Nightjar, Indian Grey Hornbill, Great Grey Shrike, Indian Silverbill, Chestnut Munia and Black-faced Buntings.