Why isn’t a bird sitting on a high-voltage power line electrocuted? Contrast this with the situation in which a large bird hits two wires simultaneously with its wings.
The bird sitting on an electric line has both its legs at the same potential, ie the supply voltage of 110V (or 220V as per the country standard). Hence no current flows through its body and thus it does not get electrocuted. However when bird with long wings touch both the lines simultaneously, a potential difference equal to the supply voltage is formed across its wings. Thus current flows through the bird electrocuting it.