Tail Wags and Body Bobs.

[Synn]

Is there a reason why blackbirds, Magpies and Wagtails wag their tails, as well as why Redshanks and Dippers Bob?

I was thinking it could be signalling to a mate, or a terratorial display, or (with the bobs) a similar thing with pigeons bobbing their head to keep their eyes in focus.

But is there a know reason why birds do this?

[Picidae]

There's lots of reasons why birds wag their tails but I think the jury's still out as to exact reason why for particular species.

With ground insect feeders like Wagtails, it's thought the tail wagging, flushes up insects from the ground, and in low densities, helps to create flashing of shadows so insects are startled by changes in light. Yellow Wagtails, it's thought, possibly wag their tails as cameoflage when near water so this might also be an explanation for Dipper tail wagging.

It's also thought the tail wagging helps with balance when foraging for food on the ground. Pipits eg. tend to wag a lot I've noticed.

Communication could be another possibility especially when birds are singing - Robins, Blackbirds some warblers I've notice are excessive tail waggers when singing (not sure if that's a coincidental motion more to do with physiology though!) but especially when alarming relating to predator alert and territory defense (perhaps it makes them look bigger - part of a fluffed up strategy!)

Sandpipers (Green and Common) both use extensive rear bobbing motions when foraging so perhaps lends support to the balancing purpose of tail wagging in some species?

[Synn]

Thank you!