When pigeons walk, they bobble their head forwards and backwards with every step. Other birds do it too. But by no means all: sparrows and tits don’t. So first I wondered if this was because sparrows and tits jump like kangaroos while pigeons put one leg in front of the other a bit like we do. But then I saw a roadrunner walking (and running) and they don’t bobble. Ostriches sometimes do, but not always. Ducks don’t bobble either. But crows and ravens do. Chickens do too, of course.
Why?
Are there two lineages of birds, one that bobbles and one that does not?
And if so: did dinosaurs bobble, and some birds have abandoned that way of locomotion? Or did some birds gain it later, while some have kept the ancient, dinosaur bobble-less style?
Are there other animals, apart from birds, that exhibit a similar behaviour?
No traction at all. I miss Colibri. Who curates critters now?
Interesting. Your note that hopping birds don’t bob their heads makes me think.
Most animals including us, generally move more than two limbs when moving. So we can substitute bobbing our heads for counter action and balance, by the movement of our other limbs. Four legged animals do it as a more direct mode with their actual walking limbs. Humans do it with swinging our arms.
But it would be quite a bit more awkward and energy poor for a bird to stretch out and waggle there wings as they walked.
I think birds also use tail movements as they walk to balance.
It does seem a bit slight. The bobbing of a pigeons head to counter balance. But maybe it blends in with other less obvious things to get the job done.
Apparently the jury is still out on all the details.