India's northern plains, the course of the holy rivers Ganges and Yamuna; the Thar Desert in the west; the Sundarbans, the marshy swamplands, in the delta of the Ganges and the Brahmaputra, in the east; the Deccan Plateau, lying in the rain shadow of the hills and the Western Ghats with their dense; luxuriant forests - all provide fascinating variations in habitats. These forests sustain 350 species of mammals, 2,100 kinds of birds (both local and migratory), nearly 350 species of reptile and countless insects.