Fiddler on the roof

Pied wagtail

Pied wagtail in winter plumage

Actually not a fiddler but a wagger.

This is a Pied Wagtail, a frequent sight by the house.

It wags its tail up and down to regain its balance after landing.

An apt name, which actually describes what something or someone does, is an oasis in the muddle of language.