Black-headed Wagtail

Motacilla flava melanogrisea (M. f. feldegg var. melanogrisea)

 
Black-headed Wagtail male Black-headed Wagtail male Black-headed Wagtail reflection
The Black-headed Wagtail is one of the Central Asian subspecies of the Yellow Wagtail; this subspecies, from southeast Kazakhstan, is sometimes called the Turkestan Black-headed Wagtail.
Only the male has the bright yellow front and black head; his back is olive and grey like the nominal Yellow Wagtail, his chin is white.
Black-headed Wagtail yellow front Black-headed Wagtail Black-headed Wagtail
The bright yellow front and white chin  
Black-headed Wagtails fighting Black-headed Wagtail Black-headed Wagtail
Fighting for territory but the action is too quick for the camera    
Black-headed Wagtail Black-headed Wagtail Black-headed Wagtail
The female Black-headed Wagtail doesn't have a black head. She has a grey head and back, less rich olive than the male and her front is pale off-white and yellow.
She also has the hint of a white eyebrow.
Black-headed Wagtail Black-headed Wagtail Black-headed Wagtail
 

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Grey wagtail
Grey Wagtail