These Grey Wagtails, Motacilla cinerea, are so beautiful.
In Italy they are not known as Grey Wagtails, they are known as Ballerina gialla. That’s a much more fitting name:
I’ve tried and failed previously to get a reflection of a Grey Wagtail in a pool in very poor light in Devon:
It really was a grey Grey Wagtail on the greyest of grey days. Here at Lago di Alviano in Italy it’s a beautiful January day with low sunshine and this Grey is stepping nicely into the shallow reflection pool:
They appear very restless, active birds, with constant tail bobbing and occasional wing flicking. The question is: why do they wag their tails? The answer is, as always, that those who wagged their tails had more offspring who had more offspring until all the wagtails wagged their tails. Why, then, would it help them have more offspring.
There are various possibilities: it could help them:
Find more food – wagging your tail could disturb the sort of insects you eat and therefore be a good foraging strategy.
Avoid predators – wagging your tail could show potential predators that you are alert and they should not waste their energy trying to catch you. It’s a, “Don’t even bother trying, I can see you.” signal.
Improve camouflage – wagging your tail breaks up a still outline and might help you be camouflaged better against a moving backdrop of streams and running water.
Alternatively I’ve had it suggested to me that they wag their tails because they are happy.
If I had a tail I’d be wagging it right now.