Eleven subspecies of the White Wagtail (Motacilla alba) are currently recognised and they all have slightly different plumages.
This is Motacilla alba alba, the nominate subspecies of the White Wagtail which occurs on the European continent and migrates down as far as Kenya.

On one morning, just outside our hotel in de Pfänder Mountains, I found a family of White Wagtails, including 3 juveniles that were getting fed by their parents.
Most young songbirds have a thick yellow border around their beak, which makes them easy to identify (clearly visible on the first 3 photos). 
This encourages the parents to put food in it.
The chicks open their beaks wide when the parent bird comes with food and also start to squeak loudly.

Gasthaus Moosegg, Pfänder Mountain, Bregenz, Vorarlberg, Austria, 2 August 2020