What the head bobbing lets pigeons do is momentarily fixate their eyes on objects. This gives the photoreceptors in their eyes enough time—about 20 milliseconds—to build a steady scene of the sidewalk world. And this has nothing to do with their bird-size brains. Vision doesn't mix well with movement.
All animals, from insects to eagles, have tricks to stabilize the world. Many mammals, humans included, do this with slight twitches of the eye. This is instinctual, and comes from neuromuscular connections between our eyes and the part of your brain that tracks movement and rotation.
Pigeons are able to move their eyes, but their longer, more flexible necks make it more efficient for them to do this motion tracking with their necks. So, all this time we've been ridiculing pigeons for their quirky gait, and it turns out we were just seeing it the wrong way. And the reason why pigeons practice this behavior, it turns out, is all about the way that these birds see the world. The researchers in the landmark treadmill experiment discovered that if a pigeon's visual surroundings stayed relatively stationary around the bird as it strutted on the treadmill, the animal's head didn't bob.
Through reverse logic, this led to the central discovery: Head-thrusting helps pigeons to stabilise their view of the moving world around them. In other words, a stationary head gives the bird a moment to visually process its surroundings while it waits for its moving body to catch up; it's like hitting pause on the motion for a fraction of a second. This tactic is useful because it "enables them to see potential food — and possibly, enemies," Land said.
If pigeons' heads moved at the same pace as their bodies, "they would have trouble keeping a stable image of the world on their retina," Blaisdell explained; the surrounding scene would swim by in a confusing blur.
Blaisdell also shared an endearing anecdote: During research in his own lab, when he picked up a pigeon and walked forward with it, the bird still bobbed its head, because the world was still moving around the pigeon even though the animal wasn't moving of its own accord.
Related: Pigeons Vanish in 'Birdmuda Triangle'. This visual trick isn't just a quirk of pigeon life. Humans do a version of this too, except that instead of moving our heads, we use rapid, jerky movements of our eyeballs to help fix our vision as we move through space.
If you like, you can go "coo coo" at the same time. Phil Cohen, Sydney Australia They have their scarves tucked into their belts! Mikhaila, Cardiff UK It's to keep their vision steady as it compensates for up and down movements in their bodies when they walk. If it was to get an approximation of binocular vision, they'd carry on bobbing when they stood still, which they don't.
Instead they move their heads from side to side. Have a guess what that's for Toby, Canterbury, UK I have always assumed that pigeons, like chickens, do not have sufficient brain capacity to process moving images. The head is not bobbing, but moving from one fixed point to another and recording a series of stills. Try gently chasing a pigeon - its head will speed up as it walks faster. This desire to keep the head in one place can be demonstrated by holding a chicken and moving it from side to side and up and down.
The head stays where it is. This even works if the chicken is turned upside down, until, of course, its neck can stretch or bend no more.
The limited brain capacity also means that the bird is unlikely to retain any psychological scars from this experiment.
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