Motacilla citreola
Adult male easily recognized with all yellow head with dark edges and grey back. Prominent white wing-bars and all dark bill, lacking the pale base of Yellow Wagtail. Females and adult winter lacks the dark lore-stripe of Yellow Wagtail, and the flanks are grey. The same applies to the juveniles. These also give a very grey impression, almost resembling a Pied Wagtail without the dark breast-pattern. Juvenile Yellow Wagtails have a less grey and more olive tone to their backs. The dark facial markings/earcoverts of females/winter/juveniles birds are usually framed by the continuation of the strong supercilium. Some Yellow Wagtails are very similar to Citrine, and call and tail length should be considered as well (tail longer in Citrine).
Contact call resembles Yellow Wagtail, but is harsher with a more buzzing quality, and of shorter duration. The pitch is more constant, lacking the rise and fall of Yellow Wagtail. The song is a loose repetition of phrases, comprised of disyllabic or monosyllabic contact calls.
Wikipedia: map (se also Xeno-canto below)
Birdlife ecology
Sounds:Recorded by Jelmer Poelstra,http://www.xeno-canto.org ,CC license
