The book Sikkim Located in the northeast part of India, is a paradise for ornithologist. Bird of Sikkim shows a total of 524 species. Salim Ali extensively reviewed the part studies substantiated field surveys and published a book containing a comprehensive lest of species distributed in Sikkim. The basic information of ecology of some species is also provided certain well-known migrants such as wild ducks and geese can be seen passing over Sikkim regularly in autumn and spring, and some other species are known to spend the winter or a part of that season at lower altitude. The Lachen valley is reputedly a traditional flyway for duck and geese at least on the northward direction in spring. Several other pecies of duck fly over Sikkim on their autumn and spring migrations, but owing to the absence of suitable shallow Jheels very few stop over and only transitory.