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Kancelas t1_ixuei0y wrote

Their heads work like a gymbal for cameras completely isolating their heads of any movement when walking.

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Internet-of-cruft t1_ixv19hf wrote

This is correct. I used to work on the design of cameras for an aviation company and one of the contacts we were awarded was to design a new low friction mechanism gimbal for small camera systems.

As you would imagine, in aviation you're heavily space and weight constrained so it meant lots of careful design to fit the allocated constraints.

You can imagine my surprise when I learned that the government wanted to sign an exclusive manufacturing contract when they learned that we were producing this commercial for airlines. Help I've gotten myself so deep into this compulsive lie I don't know how to stop. The governmeny turned around and ended up using it in most regent design for birds and due to the lowered friction it resulted in a more prominent head bobbing.

So yeah, pretty spot on.

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ThePhoenixBird2022 t1_ixurf6x wrote

Their eyeballs aren't as moveable as ours. In the birds you have mentioned, their eyes are also at the side of the head. Their eyes, food intake system (beak/mouth - wasn't sure of the correct terminology), airway and sinuses take up most of the head so they eyes don't have much movement. It's a bit of a look around - body catches up, look around, body catches up, repeat thing. Or it's a look around, not happy, retract the head and go the other way or fly away sort of thing.

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MountNevermind t1_ixuxo0l wrote

Their eyes need a certain amount of time to fix on an object while they are moving. That bob is the only means they have to get a fix on something for the 20 milliseconds or so it takes since their eyes don't move like ours do. With the visual information they get by doing this over and over, their brain can put together a view of the world on the ground that is steady and makes sense for them.

Brains, be they pigeon or human, form a visual awareness by selectively picking and choosing from all the information that comes from the eyes and even filling in the gaps with "guesses" and reducing visually confusing things like the effects of eye/head motion. It's not like a monitor hooked up to a raw camera feed that shows everything, including the movement involved when the camera moves around. The birds likely don't "notice" the movement visually too much.

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cuby87 t1_ixurq47 wrote

It is the optimal way for their head to be in movement the least amount of time. They move their body as far forward as they can before the head has to move, then move the head as far forward possible as fast as they can, and repeat.

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Neither_Tomorrow_238 t1_ixzme2u wrote

head bobbing allows pigeons to momentarily fixate their gaze on various objects, giving the photoreceptors in their eyes enough time—about 20 milliseconds—to build a complete picture of the world around them.

And while it often appears as though the birds are moving their heads back and forth, there’s actually no backward movement at all. The bob is actually an illusion, scientists discovered in an experiment. The birds are simply moving their heads, allowing their vision to stabilize so their bodies can catch up, and then they’re on the move again.

This happens so quickly, it appears as though they’re using a constant bobbing motion.

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TMax01 t1_ixzvzur wrote

As with all questions about why animals do any specific thing, the ultimate answer is simply "those that didn't died out". So the question of why do birds that bob their heads have an evolutionary advantage over those of their species that didn't does not necessarily need or have a single absolute answer.

In this particular case, three major proximate reasons (any of which might have more or less impact in any particular case) are:

  • tracking: the mechanical movement is actually lack of movement, because keeping their eyes nearer a fixed level is less energy-intensive than using their brains to compensate for the movement of their heads while walking

  • balance: to lower their center of gravity to make toppling over when they lift one leg to step forward less likely

  • leverage: by moving their heads in an opposite direction to their bodies, they use less energy in locomotion

Thanks for your time. Hope it helps.

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