The sight of a flock of birds perched on power lines is familiar to anyone who's lived around our modern electrical infrastructure. While it's a common sight to see, you may have found yourself wondering why birds perch on power lines or how it's possible without electrocution. EnergyBot is here to help you understand your power system, including how it interacts with nature.
Most people have a general understanding of electricity — or at least know that being electrocuted is bad. We stay away from things we believe will shock us and know that metal conducts electricity while rubber insulates against it. So how does electricity interact with organic material — birds, in particular? Consider that power lines carry an electrical current. Electricity tends to flow along the path of least resistance, and power lines contain copper wires that encourage steady transmission.
Birds can perch on electrical lines because they don't conduct enough electricity to disrupt the current. The electricity flows through the bird and back to the wires. Electrocution would occur if a bird touched two wires, a wire and the ground or a wire and a pole simultaneously. However, perching birds are safe from shocks because they only cling to an individual power line.
Now we know that birds can sit on power lines, so why do they do it? The answer is the result of a perfect storm between evolution in the animal kingdom and human technological innovation.
Natural selection in small songbirds has favored those birds that can grip branches or twigs with their feet. Most songbirds have three toes that stick forward and one at the heel, going the opposite direction. Their talons allow birds to sleep, feed or preen high above their predators.
Power lines are similar enough in structure to branches for birds to recognize them as a great place to perch. The entire flock can congregate in one area for the combined safety of numbers and height. Plus, fewer "branches" make it more difficult for predators to climb power lines than trees.
Power lines make an excellent stopping point for birds that conduct such low amounts of electricity that they can perch safely. But is it a perfect match?
Fortunately, it's rare for perching birds to cause power line damage. Most birds are light enough that lines can handle their weight, even in high numbers. Issues are more likely to arise when larger birds collide with lines while flying or when woodpeckers chip into the poles.
However, nesting on power lines can present issues when the nesting materials poke through the power lines to damage the cables inside. Some birds will even peck at the wires to use in their nests. However, perching birds are generally only a minor concern for electric line damage.