How Do Birds Sit on Power Lines without Getting Electrocuted?

by Kate Repantis on January 16, 2014 · 31 comments

in Modern Geekhood

Guest Post by Aaron Johnson from the Ask an Engineer series, published by MIT’s School of Engineering

You’ve probably never seen a bird straddle two wires at once, and there’s a good reason for that…

Photo: Doug Waldron

Photo: Doug Waldron

It’s not uncommon for a character in the movies to end up with a blackened face and a headful of frizzy hair after touching a live electrical wire. What makes for a good gag in the entertainment biz, however, is likely to kill you in real life—unless you’re a bird. Birds have no problem sitting, unruffled, on the high-voltage power lines you often see lining the road. This ability has nothing to do with them being birds, explains Ranbel Sun ’10, MNG ’13, a recent grad in electrical engineering who currently teaches at Phillips Academy in Andover, Massachusetts. It’s all about the connections they’re making—or, more importantly, not making.

“Electrical current is the movement of electrons,” explains Sun. The movement of electrons through a device like your TV is what gives it the energy to display images and produce sound. Sun describes the long process these moving electrons take to get to your house. “The electrons are essentially being pulled from the ground by the power station,” she says. “They move through the power lines, through your TV, and eventually they make their way back into the ground from where they came.” This creates a closed loop, which is required for electricity to flow.

The other thing electrons need in order to move is motivation—or, more specifically, a difference in what’s called electrical potential. “Imagine lugging a bunch of bowling balls up a mountain,” Sun explains. “If you give them a path, the balls will naturally roll down the mountain to a lower position.” At the top of the mountain, the bowling balls (which represent the electric current) have a high potential, and they will travel down any path that becomes available. When a bird is perched on a single wire, its two feet are at the same electrical potential, so the electrons in the wires have no motivation to travel through the bird’s body. No moving electrons means no electric current. Our bird is safe, for the moment anyway. If that bird stretches out a wing or a leg and touches a second wire, especially one with a different electrical potential, it will open a path for the electrons—right through the bird’s body.

There are other perils for our feathered friends, Sun points out. “The wood pole supporting the wires is buried deep in the ground,” she says, “so it would also be dangerous for a bird to sit on the pole and touch a wire.” Read more.

Authored by Aaron Johnson. Thanks to Naveen Surisetty from Visakhapatnam, India, for this question. Visit the MIT School of Engineering’s Ask an Engineer site for answers to more of your questions.


{ 31 comments… read them below or add one }

Rejith January 16, 2014 at 8:43 am

Above picture is look like birds sitting in Pixar – For the Birds (animated short film). Informative article, thank you Kate.


mako January 16, 2014 at 11:17 am

wow – what could’ve been answered by one simple sentence evolved into a long lecture…technical types need to learn the art and skill of clarity and brevity…and i’m one of them 🙂


Mark May 2, 2016 at 10:36 am

I found the explanation thorough and complete. A good technical writer is lengthy so as to ensure understanding. Shorter answers run the risk of confusing those who need more.


Jae August 9, 2016 at 3:01 pm

I agree!!!


Tara Roushdy April 12, 2017 at 6:06 pm

Mako, I agree.


David Kazdan January 21, 2014 at 8:39 pm

For work on extremely high voltage lines, the linesman needs to wear a suit of chain mail. Otherwise, even the atmospheric electrical field is too great for safety. IEEE Spectrum ran an article on this, but this tells the tale:
Doesn’t seem like at all a good idea.


Rejith kumar January 31, 2014 at 2:27 am

David, your are right. I saw that video clip, awesome information and thank you !


Mina March 13, 2014 at 2:04 pm

I think birds all face the same direction on the power line because they need to land and take-off into the wind.


Jason July 29, 2014 at 10:33 pm

I really thought that most of the birds that are electrocuted on power lines are those that are sitting on lines which were either broken or which has a bad line.


ed September 19, 2014 at 4:45 am

I watched a program when a technician was sitting in a helicopter holding a metal rod out to make contact on the the live wire before he could touch the live wire himself, why is that?


Kim OBrien December 24, 2014 at 3:26 pm


The three physical properties that govern the flow of electricity are capacitance, inductance and resistance. Depending on the particular circuit you can sometimes rule out one or two properties as being important. With the bird I ruled out capacitance and inductance because of my general experience with electricity. The surface area of the bird and the head to toe distance are the actual reasons why I believe they have little influence in this case. This leaves the resistance through air which once again due to experience I believe to be a large number but the significant factor preventing bird electrocution. I did not actually do any real calculations to prove my point and I have never heard anyone say this explanation is wrong.

With the helicopter I believe capacitance is the governing property. Why? general experience again. With a capacitor in an AC circuit current can flow with the charge (electrons) collecting and leaving the plates but never crossing them. This explains why there is a spark between the helicopter and wire but no spark between the plates (helicopter and ground or another high wire). So because the area of the metal skin of the helicopter is so large compared to the bird, capacitance became a significant factor. The rotating blades may also play a role but I’m not really sure how to assess that.

Also sparks are much more impressive than the actual power needed to produce them. I make that statement based on VanDergraph generators (lots of sparks bit little actual feelings), personal experience, and a video of a man on PCP grabbing a 2300 volt high wire while standing on a low voltage cable being covered with sparks and living to tell about it.


Maureen Coffey November 26, 2014 at 11:42 am

They actually DO get electrocuted – in rare circumstances, though. There have been repeated cases where storks or other large birds have been sitting on high voltage power lines and then “kissing”, i.e. touching with their beaks. This of course then was the last of them …


Kim OBrien November 29, 2014 at 11:03 pm

To bad no one who actually understands power generation like a licensed electrician. “The electrons are essentially being pulled from the ground by the power station.” This is essentially and confusingly false. The generator is the machine that changes mechanical energy into electrical energy. The electrical generator (alternator) takes advantage of a property call induction to make the electrons in the generator wires move back and forth in response to a changing magnetic field. Only an unwanted minority of the electrons actually move through the ground. The great majority move through wires unless something goes wrong which is why we ground most circuits. The grounding is done for safety. When a significant amount of electricity is traveling through the ground that is called a ground fault. A ground fault will often trigger safety equipment that will shut down a circuit.

If we were to use the ground as a major conductor “electrons are essentially being pulled from the ground ” we would be constantly replacing ground rods due to electrolysis and creating all kinds of dangerous and unwanted ground loops.


David Kazdan December 1, 2014 at 10:49 am

Agreed completely. The statement in the article is wrong.
There were telephone systems long ago that used earth as one side of the circuit, but certainly not power systems.


Rick M November 19, 2016 at 10:28 am

It was Telegraph that used a Single Wire to transmit signals, using the ground itself as a return. The telegraph was neither AC nor DC but single pulses of Morse Code so it worked just fine. The operator translated the code and wrote out the message.

When the telephone was introduced business men said, “No thank you – we need something IN WRITING!”


kevin July 12, 2015 at 9:20 am

We could ask ourselves why are they sitting there in the first place.
Maybe it’s a energy transference? we have been observing the Starlings behaviour for many years now and our theory is actually the former,we also discovered that there are massive water veins crossing at intersections where the sitting takes place.We also studied there nesting sites which were again obove major underground water crossings,we followed these water crossings and came up with wells with massive flow rates,more energy.In recent year’s we have noticed that they are perching in massive pine trees next to some mobile base stations where a high pitch communication takes place.Were in Spain and this behaviour is taking place when the temprature is at it’s highest usually between the hours of 2pm 4pm again we discovered high output water veins at these locations.
two instruments were used as part of the study: A OKM exp5000 ground penetration radar was used to as a visual representation of the water veins in real time.A Gigahertz HF 59B was used to capture the direction and signal output at the mobile base station.In this case the highest readings were taken in the direction from the trees in which the Starlings were perched.
Anyway it’s food for thought”


Rick M November 19, 2016 at 10:36 am

Fascinating answer. Thanks for posting it.

Fifty years ago when high voltage lines were first put up the wires were under stress during the mounting process and would often acquire a slight permanent strain. A thinner wire had higher resistance, so the thought was that the birds could tell which parts of the wire were slightly warmer!


Paul October 31, 2015 at 10:58 am

That explains the extinction of the large flying reptiles who leg span probably was large enough to touch two wires.


Kim November 10, 2015 at 4:42 pm

While being insulated from ground potential I can feel the 60 Hz vibration on a bare copper wire connected to 120 volt ‘hot’ line voltage by gently touching the bare metal with my index finger. The voltage on those wires as shown in the picture is somewhere around 100 KV so even though they are insulated from both the aluminum wire and ground it might be possible that the birds feel something similar.


Kim November 10, 2015 at 5:07 pm

The picture shows them sitting on both high voltage transmission wires (75-300KV 0r s0) distribution wire (10-20KV) and either/or low voltage customer, ground/pole support or telco cables. At the lower voltages I doubt that the birds can tell the difference between ground and 120 volts. Why? because a birds body doesn’t make as big a capacitor as my body does.

Other experiments have shown that migratory birds can determine magnetic north so maybe they enjoy the 60 Hz magnetic fields from the current carrying wires.


Kim November 10, 2015 at 5:28 pm

Actually looking even closer the birds do not appear to be sitting on the 75-300 kv lines only on the top ground wires for the transmission circuits.


Frank January 9, 2016 at 9:38 am

Great photo. Birds only sit on the top wire, but not the lower ones, in the background tower. Why? Do utility engineers need to design the wires to withstand the weight of the birds? This photo can serve as a great topic of conversation during a job interview.


Fr May 27, 2016 at 2:29 pm

that still doesnt make much sense. No any creature or thing can do two things at the exacts same time. So one foot will always be faster than the other, even though its 0.00000000000000000001 of a second. Its still enough for a tiny bird to get electrocuted. And besides that.. are we just going to ignore the fact how smart and intuitive birds are? Praise nature! it always wins.


Stanton de Riel August 24, 2016 at 9:38 am

You don’t see birds sitting on high-voltage lines in nature. If you stand under some (particularly in humid weather) which dip close to the ground, you can hear corona discharge crackling. A conductor (like a protruding bird) would serve as a reverse-lightning rod on the line — a focal point for discharge of current. Having handled a corona-discharge static-removal wand in the lab (whilst standing in two rubber wastebaskets, for safety!) I can attest that a bird would feel the field.


Mik November 15, 2016 at 11:55 am

I thought that on extremely large voltage lines if the birds widen the legs enough (on the same wire), they can still get electrocuted. Same for cows walking on the ground under the power lines.


Munna Bhai Btech November 30, 2016 at 1:42 am

I am going to stand on a live wire with both my feet touching it. If i get harmed, i will find you and i will….. (Whatever Liam Neeson says in the Taken movie).


webkulturel December 15, 2016 at 2:29 pm

I really wondered that how they can do it. But I happy that they don’t die


zoe February 14, 2017 at 1:22 pm

Why dont birds get shocked


tunji March 22, 2017 at 3:37 am

Well,i really tink d question hasn’t bn answered!……if u ask a lay man d question,he’ll jst tell u “hey i tink birds gat scaly feet which are as good as insulators”!….i tink datz jst it!…..and i tink datz why bats get electrocuted everytym dy touch a HVTL..


Tara Roushdy April 12, 2017 at 6:07 pm

I always figured that birds don’t get electrocuted because the wires are covered in rubber (a poor conductor of electricity).


NEIL ARNTZ April 20, 2017 at 7:48 pm

There are other perils for our feathered friends, Sun points out. “The wood pole supporting the wires is buried deep in the ground,” she says, “so it would also be dangerous for a bird to sit on the pole and touch a wire..



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