I am a bird. My species' population is on the rise unlike many other species of birds. My colour is generally pinkish-white. I stand around 1.5 metres (5 feet) tall in height and weighs between 2 – 4 kilograms. I am a migratory bird. My species come in thousands to build nest mounds from the salty mud in the Rann of Kachchh. Who am I?