On behalf of Dale who sent in an email:-
there are a pair of birds which I have noticed in the land around our house in Spain. We are in Hondón de Las nieves, in the Alicante region of Spain, inland from elche. The birds behave like wagtails, and are a similar size the pied wagtail we see commonly in England. These have a black head and back, but strikingly have a red tail.
Do you have any clues what it might be?
I didn't get a photo, but could try, it won't let me get very close, and it's just a phone camera!