Why does a bird can sit on a wire of electric line?

Many times we saw birds on a wire of electric line. Why don’t they feel high currency? The thing is that the distance between the legs of such a bird is tiny. The voltage on this wire zone is directly proportional to the resistance which is very small due to the very short length of such zone. But if a bird touches some other grounded object, for example metal part of the pylon it will be killed because the voltage is too high.