Why don't birds get electrocuted on power lines?
Short answer
If a bird touches only one power line with both feet, there is usually very little voltage difference across its body, so only a small current flows through it.
How it works
Electric current flows when a voltage difference creates a path between places. Two nearby points on the same wire are at nearly the same voltage, so the bird’s two feet are usually at nearly the same voltage too.
If the bird touches another wire or a grounded part of the pole at the same time, it can complete a path for current. In that situation, current can flow through the bird and cause electrocution.
Key point
The bird is not safe because its body cannot conduct electricity; the contact pattern is what matters. Larger birds that can bridge the distance between wires or hardware can still be at risk.