Yellow Wagtail (Motacilla flava iberiae) Alvéola amarela
The smallest and most compact of west Palearctic wagtails with bewilderingly complex systematics and forms/races. Previously there were two large colonies in Ireland (Killala & Belfast) but these were extinct by 1941. Occasional breeding has occurred since, usually on East Coast at Kilcoole and in the 1980s in Rogerstown, Co Dublin; generally in potato fields.
This one was photographed in Santa Luzia, nr Tavira, in Portugal and is of the Iberian race.