Dunlin (Calidris alpina)
One of the smaller waders and our most abundant one in winter and on passage. A limited number breed in some sandy / grassy locations along the west and north coasts. Plumage is highly variable - in summer, rich chestnut above, streaked on breast, white below with a striking black patch on the belly. The more usually encountered winter plumage bird shows a rather non-descript, uniform, plain brownish-grey on all upperparts and cold white underparts. Juveniles in autumn have warm brown tones on the upperparts and considerable streaking on the breast and underparts. There are many other variations and combinations, depending on the bird's state of moult. It is a rather dumpy bird, with black legs and a longish bill which downcurves slightly. Often occurs in very large flocks. An important bird to get to know (in all its plumages) if you want to successfully identify other similar-sized waders.
Pictured here on breeding grounds in Co. Donegal.