Why don't birds get electrocuted on power lines?
Electricity only flows when there is a voltage difference across something, and a bird touching one wire has both feet at the same voltage, so there is nothing to push current through it.
Simple intuition
The plain reason, in everyday words
Electricity does not want to be somewhere in particular. It flows when there is a difference in electrical pressure between two points, and it flows from the higher to the lower. That pressure difference is what we call voltage. When a bird lands on a single wire, both of its feet are on the same wire, a few centimetres apart. There is essentially no pressure difference between one foot and the other, so there is nothing to push electricity through the bird. It is not that the bird is protected, insulated, or lucky — it is that no push exists. If that same bird stretched out and touched a second wire at a different voltage, or touched a wire and a metal pylon at the same time, current would flow instantly, and it would not survive.
Birds' feet are insulated, or their scales protect them.
Bird feet are ordinary flesh and conduct perfectly well. Insulation is irrelevant to why they survive; the absence of a voltage difference is the whole explanation.
Power lines are insulated, so touching one is safe.
Overhead transmission and most distribution conductors are bare metal. What insulates them is the air gap and the glass or ceramic insulators at the pylon, not any coating on the wire.
Rubber-soled shoes will protect you like the bird is protected.
Two different situations. Ordinary shoes are not tested insulation and fail readily at line voltages, and they provide no protection at all against a current path that goes hand to hand rather than through the ground.
It is the voltage that kills you.
Current through the body over time is what causes harm. Voltage matters because it drives the current, but the same voltage across a dry palm and across wet skin produces very different outcomes.
It replaces a vague fear of electricity with a usable rule: harm requires a completed path between two different potentials through you. That single idea explains why birds are fine, why line workers can touch live conductors, why you shuffle away from a downed cable, why three-pin plugs have an earth pin, and why an electrician keeps one hand in a pocket.
Who worked it out
Georg Ohm published the relationship between voltage, current, and resistance in 1827, to a notably cool reception; it took over a decade to be widely accepted.
What problem forced it
The practical stakes arrived with electrification in the 1880s, and the safety implications were argued out publicly during the war of the currents between Edison's direct current and Westinghouse's alternating current, in which electrocution risk was used as a marketing weapon by both sides.
How it changed since
Systematic understanding of electrical injury came much later, largely from twentieth-century work relating current magnitude and duration to physiological effect, which underpins modern standards. Bird protection specifically became a regulated design concern from the 1970s onwards, as raptor deaths on distribution lines were recognised as a significant conservation problem.
Why three-pin plugs have an earth pin
The same principle applied deliberately, to guarantee that a fault has a safer path than you.
Why birds sit on wires at all
The behavioural question the physics answer leaves open.
Written for Curio rather than collected from a forum — it is part of the curated corpus that ships with the platform. The references it draws on are listed under Sources.