Another little known fact about the Yamuna is that it is the frontier of the Indian Elephant. West of the Yamuna, there is no Elephant in 900 kms of the western Himalaya or it's foothills. The forests of the lower Yamuna offer ideal corridors for Elephant movement and the principal forests to be found here are, Sal, Khair Sissoo forest and the Sivalik chir- pine forests. Nearly 18,000 species of butterflies have been discovered worldwide and they have become a key test group for ecological and evolutionary research. They also serve as key indicator species for environmental disruption.
Butterflies are interesting for other reasons too.
The way they protect themselves from predators for example. Some have vivid designs like eyes to draw attention away from vital body parts and onto the fringes of the wings. It's obvious why this one is called the jewel fourring.