Why Birds Stand on One Leg

Have you ever asked why birds stand on one leg? We live on a river that has a massive number of ducks in it. When the ducks are resting on the edge of the river, they generally stand on one leg. When guests visit us, they want to know why. Ducks are not the only birds that stand and even sleep on one leg. Geese and Flamingos do the same thing.

The answer to why birds stand on one leg seems to be a simple matter of the application of basic physics. For an object to be stable, its center of gravity has to be directly above the point of support. In my basic physics classes, we have some demonstrations of that principle. A spinning bicycle wheel will do strange things if its pivot point is not under the center of gravity. A top that is not symmetrical will invert when spun with its round side in touch with the table. There are toys that appear to be suspended in space, but in reality, their center of gravity is located at one end which makes it look odd when it is on the edge of a table.

When you stand on two legs, your center of gravity is somewhere between the legs. That may sound stable, but in reality, it isn’t. When you stand, you waver as your body senses that any movement you make throws you off balance. There is a constant muscular effort that counteracts this movement. Just standing for a long time can be fatiguing because a lot of energy is expended to counteract this wavering.

Recent studies with flamingos show that when they stand on one leg, the center of gravity falls directly over the point that touches the ground. Standing on one leg, the bird’s body is quiescent. When the bird is on two legs, there is more muscle movement and the center of pressure on the foot touching the ground changes. If you look carefully at a duck standing on one leg, you will see that it stands a little lopsided, so the mass is completely above the point of support. In addition to energy conservation, standing on one leg allows birds to withstand cold temperatures by keeping one leg close to the body. So thermoregulation is also involved in this odd-looking design.

So if you have ever asked why birds stand on one leg, remember this. Anytime we see something in nature that we don’t understand; it is almost 100% sure that there is a design feature involved. What the animal is doing may look strange, but it has at least one significant function. Truly we can “Know there is a God through the things He has made” (Romans 1:18-20).
Data from Science News, June 24, 2017, page 15.
–John N. Clayton © 2017