Жёлтая трясогузка

Still not sure is it leucocephala subspecies or hybrid. Any ideas?

E.Panov wrote that some of hybrids feldegg x beema are almost identical to leucephala. We regularly found white-heded Yelow Wagtails in Kazakhstan (I saw one two days ago), probably birds from the eastern part of republic are lecocephala but ones from wester part are really hybrids feldegg/melanigresea x beema. Gallery.