They are large birds with a wingspan of 152cm (60inch). The casque on top of their bills are hollow, concave and serve no known purpose. They are monogamous and often build their nests in the same place every year. Before mating, they clean up the nesting hollow and engage in a little courtship involving food exchange. The female will spend increasing amounts of time inside the nest. When the eggs are laid, she sheds her breast feathers and seals herself inside the nest, leaving a vertical slit for the male to feed her. Here we see their pre-mating preparations.
India