Why do cockerals wobble their heads from side to side?

A couple of mine do this, one I noticed picked up the habit after he'd been fighting. The hens dont seem to do this. Its like they tilt their heads back and wobble side to side.

Also one of my cockerals makes a cackle noise but the others dont do it, its almost like he's laughing at me. He normally does this when I walk away as if to say come back and give me some more treats.

I just wondered if anyone can shed any light on this kind of behaviour.

Thanks