Weasels are stealthy and cunning creatures. They know the best way they can achieve what they want. In Sierra Leone, weasels in the forest live almost exclusively in the trees and rarely venture down to the forest floor where their lives might be in danger. Weasels quickly worked out that to move from tree to tree could be problematical. Jumping from branch to branch might work sometimes, but not always, especially if distances were more than a few feet.
The weasels of Sierra Leone worked out a way of moving around the forest. They hitched rides on the backs of the larger birds such as woodpeckers, parrots, and crows. The birds didn’t enjoy having a passenger on board and tended to fly the shortest distance possible, but this suited the weasel as it invariably meant the weasel was in a tree he hadn’t visited before.
This is an extract from the book Animals Evolution Avoided