Why do pigeons bob their heads?

Asked by: Catherine Lawson, Birmingham

The most likely theory is for the same reason that we move our eyes around – to stabilise the image of their surroundings while in motion. When a pigeon is walking on a treadmill, so that its environment remains relatively the same, its head does not bob. Not all birds bob their heads, though, so the issue is still partly unresolved.

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.