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On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

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Previous Week's Question Published: 23 May, 2002 Next Week's Question
Eyes on the target: Why birds bob their heads
Question
Why do birds bob their head when they walk?

Question
Watch chickens or pigeons walk around on the ground, and you can't help but notice that they move their heads back and forth as they walk. If they speed up their steps, the head bobbing speeds up too. Not all birds do this, but many that walk instead of hopping do.

This head motion looks silly, and it may look like random head waving, but it's not. If you look closely, or take videos and watch them in slow motion, you will see the head actually stays in one place while the body walks past it. It then is jerked forward and put in front of the body and the body walks past it again.

What this behavior does is keep the head still and in one spot as long as possible. By keeping the head still, the bird gets a better look at the world and is able to see things more clearly. It can focus on one spot for a longer period of time.

This tactic is especially useful for seeing motion. Birds are very interested in moving things: small moving objects to catch and eat (such as insects), and large moving objects that might be dangerous and need to be avoided (such as hawks). Detecting movement while you are moving is hard; the best way to do it is to stand still. The head bobbing of birds allows them to detect movement while they are moving too.

Why don't other animals move their heads like this? Have you tried it? Although you, too, can look silly while you walk, your neck just isn't long enough to keep your head still for long enough to make a difference. Birds, though, have surprisingly long necks. Even birds that look like they have no necks - such as doves, chickadees, or quail -- actually have long necks. Much of a bird's neck is coiled in an S-shaped curve hidden by the neck feathers. They can extend their necks out pretty far when they want to. It is this long, flexible neck that allows birds to bob their heads effectively when they walk.