The Heron, Serpent and the Mongoose

Once upon a time there lived a group of herons on a banyan tree. In the hollow trunk of the tree dwelt a black serpent who ate the young herons before they grew. Out of sorrow the heron, approached the crab. The crab heard of the serpent and then thought to itself, " The heron is also the natural enemy of our race. So i need a scheme to get rid of all of them". So he advised the heron to throw fish bits all the way from the house of the mongoose to the tree where it lived.
The heron did as told and the mongoose following the trail of the fish came and ate the seprent and at the same time crept up the tree and ate all the herons too.