Birds have always been known for their ability of flight. Birds are found in every continent on earth - even in the otherwise inhospitable Antarctic; they have modified themselves to their surroundings. Hence, some of them have lost the ability to fly, some run fast, some swim fast and some do all of the above; and some do none.
Birds are unique creatures as they can fly using wings. Birds use wide variety of habitats in all terrestrial, aquatic and aerial realms. Water birds are one of the above classes those have several physical adaptations to live in aquatic ecosystems. They are divided into three categories: Those who belong to the family Anatidae (which includes ducks, geese and swans), seabirds and waders (shorebirds). Of these three, the term water birds are usually hot applied to seabirds; i.e. water birds are freshwater aquatic birds.
Water birds are an essential part of the bird family. In total, there are 827 species of water birds, forming about 9% of the total strength of Class Aves. In India alone, of the 1301 species of birds found, 23% are water birds, completely dependent on their wetlands surrounding. And for these creatures, the greatest threat is from human intervention. It is estimated that since 1990, more than half of the world's wetlands have been destroyed. The destruction of wetlands will hot only result in the extinction of hundreds of species of water birds, but it would also cause the world's richest and most productive ecosystems to come to an end.