Birds can sit on power lines because their bodies are not good conductors of electricity. When a bird lands on a power line, the electrical current continues to travel through the wire instead of through the bird’s body.
The key lies in the way electricity flows. Electricity always seeks the path of least resistance to complete a circuit and reach the ground. When a bird lands on a single power line, its feet are at the same electrical potential. This means there’s no “pressure” for the electricity to flow through the bird’s body, as it would have to travel a longer and more difficult path compared to simply staying in the wire.
Still confused? Let’s get deeper into the facts and understand why a bird does not get electrocuted while sitting on power lines.
What is the Science Behind a Bird Not Getting Electrocuted while Sitting on Wires?
Power lines carry AC or Alternating Currents and here the electric currents regularly change direction. Thus, the voltage alternates between positive and negative which indicates the direction of voltage flow.
Voltage is measured in amperes or the rate of flow of charge or the difference in charge between two points. The number of cycles in every second is known as frequency which is measured in Hertz.
The voltage in the wire keeps changing and when the bird sits on the wire, its voltage also tends to change. So, the bird keeps on getting charged and discharged at the same time through the feet.
Why Does Electricity Not Flow Through the Bird?
Electricity tries to move along a path of least resistance and requires conductors to flow and so copper wires are used. On the other hand, birds are bad conductors and create resistance to the flow of electricity, so the electrical energy keeps flowing through the wire instead of the birds.
However, if the bird touches something that is connected to the ground while sitting on the wire, then there is a high chance of getting shocked. This can also happen if the bird is sitting on two wires which creates a voltage difference and the electricity starts flowing through the bird’s body completing a circuit.
Thus, this is a concern for everyone who touches the wire. So, while installing power lines, there is always a huge space kept between two wires or two power line poles and they tend to be high up with enough airflow between them.
Alternative Reasons – Bird Do Not Get Shocked While Sitting on Power Lines
The capacitance of the bird, i.e. ability of the bird to collect and store electric charge also varies, which also plays a crucial role in the flow of electricity. Birds are small creatures and have a spherical shape, so they cannot store much of the electric charge. This makes the chances of getting electrocuted negligible.
However, it can be presumed that the birds who sit on the power lines might feel a buzzing sensation when the current passes through their feet. Interestingly, you would not see small birds sitting on power lines and not big birds who have a larger capacity.
Do Birds Get Killed When They Fly into Power Lines?
Yes, based on the annual report around 10 million birds get killed when they fly into a power line. Most of the time the incident happens due to the impact of collision and not due to electrocution or shock.
However, if a bird gets electrocuted then it can happen due to –
Transmission power lines that have high voltage, and it varies between the range of 275 kV to 800 kV, which can ionize the surrounding air and this create a voltage gradient. Now, when the bird approaches this area the voltage gradient keeps on increasing. Thus, you can see that when an electrical lineman approaches the power line and even before the conducting rod touches the wire, sparks are seen flying.
Birds generally avoid these high voltage areas as when they approach these high voltage cables, they can feel a sensation that is generated due to the passage of electricity through the wires. However, if the bird is flying at full speed, then they fail to change their direction and a high voltage gradient leads to the passage of current through the bird, leading to electrocution or shock. Thus, the big falls to the ground and dies.
