but this is not possible as per laws of physics...Electricity always takes the shortest route...so when crow sits on wire...electricity has two routes...either go straight through wire or enter from one paw of crow and exit from other paw...as electricity takes the shortest route so no electricity will pass from the body of crow...hence no short circuit...but if by any means a direct contact is made by a conductor from the crow's body to the earth then electricity will try to earth and hence short circuit will occur...so no short circuit by crows is possible under normal circumstances...