Head-bobbing birds

Band-tailed pigeons bob their heads as they walk.  Photo by J.J.Meyer

Here's a fun fact:

Have you ever wondered why some birds bob their heads when they walk and others do not?
Well, only birds that walk by placing one foot in front of the other bob their heads.  Doves, pigeons and chickens come to mind.  But most perching songbirds and many ground feeders including towhees hop with two feet, and therefore do not bob their heads. 
Happy Birding!
J.J.