The salt impregnated Great Rann of Kutch is a huge, flat expanse spreading over 16,000 sq km, interrupted occasionally by small uplands that are locally called bets (islands). The Rann owes its origin to a marine transgression and is a tectonically unstable area.
Ecologically, it is one of the largest seasonal saline wetlands in the world, holding water that is up to a metre and a half deep during the monsoon. However, after October-November every year, the water begins to dry, transforming the area into a vast, saline desert. The wetland attracts a large number of waterfowl species like Flamingo, Pelican, Great Crested Grebe, Black Stork, Brahminy Duck, Common Pochard, TuffedPochard, White Eyed Pochard, Gulls, Terns, Stints, Plovers and others.
The mixture of saline flats and non-saline bets – uninhabited by humans – provide an ideal habitat for many wild creatures including the Wild Ass, Desert Fox, Desert Cat (Civet), Porcupine, Saw-Scaled Viper, Krait, Cobra and several species of lizards. Due to the presence of geologically diverse rocks, many bets also feature rich fossils, including prehistoric dinosaurs and trees. A large part of the Rann falls under the Kutch Desert Wildlife Sanctuary.
Right in the middle of the Rann, there is a slightly raised ground where monsoon water starts receding first, thus providing ideal conditions for large numbers of flamingos to build their mud nests. This area is named locally as Hunj Bet (Flamingo Island) and is renowned as the largest breeding ground of the Greater Flamingo in the entire subcontinent.