Marching Up and Down...

I find wagtails immensely funny to watch with their characteristic erratic wagging of the tail.

But why do these birds wag their tail?

There is no clearly definitive reason as to why wagtails perform their namesake but it is almost certainly be an evolutionary adapted behaviour for social signalling and improved feeding efficiency.

Wagtails are exclusively insectivores and their tails are an enormous benefit to them in catching food. Tail movements are most persistent for all wagtail species during feeding. They have two distinct techniques that they use. Firstly, when picking insects off the ground they walk or run along repeatedly picking up small items and chasing more mobile prey such as beetles and small spiders. Their tails will be seen wagging and snapping up and down or even to the sides, apparently to flush insects. Grey wagtails are also known to wade into shallow water picking up tadpoles or even lunging for small fry. Again, the tail will help power this.