Why are birds able to perch on power lines without being electrocuted?

Well this question has been asked for ages by people who can't understand how on earth a bird can comfortably perch on an 11kV line and not get seriously electrocuted.Many have argued that a bird's feet has no blood flowing or that the cables are well insulated, but thats false and misleading information.In-fact transmission lines carrying high voltage (HVAC) are insulated by air not any physical material unless their is need to.Insulating these cables is costly and uneconomical because of their long distance and heavy current.
The reason is because...

for current to flow in the birds body, it needs a live and a neutral conductor.Secondly the circuit needs to be complete.When the bird is resting on the cable, which is live, cant be electrocuted simply because the circuit is not complete.The birds body will become charged for a short period. Should the bird make a wrong move like - while resting on the cable, let its tail feathers touch the second parallel cable, it will be instantly killed by the lethal current.Both lines being live will result in a short-circuit and the birds body will receive a large current.To reduce this transmission lines are spaced well enough for the birds.It is then safe to say that when you touch any of the cables and not be stepping on the ground (Earth), you may not be electrocuted.That's why a squirrel can run across an electrical line, but sadly die when its foot makes contact with the (grounded) transformer on the pole at wire's end.You may want to try at your own risk.