Dunlin

Estuary flocks

Dunlin are the quintessential British estuary bird — present in enormous numbers on mudflats and tidal estuaries from autumn to spring. Flocks of tens of thousands perform spectacular coordinated flights over the mudflat, twisting and banking in perfect unison, alternately flashing silver-white (underparts) and dark (upperparts) as they turn. These murmurations function to confuse and dazzle aerial predators like peregrine falcons.

Black belly patch

In summer breeding plumage, the dunlin is unmistakable among similar small sandpipers: it develops a large black patch on the lower belly, visible at considerable distance. This belly patch disappears in winter, when the bird becomes a plain grey-brown above and white below — typical of winter waders. The change between summer and winter plumage is dramatic.

Sewing-machine feeding

Dunlin feed by walking rapidly and probing repeatedly into wet mud with their slightly drooped bill tip — an action so rapid and continuous that it has been compared to a sewing machine. The drooped bill tip (a slight kink at the end) is an adaptation for feeling invertebrates in soft sediment. They feed primarily on worms, small molluscs, and crustaceans.

Breeding on moors

In Britain, dunlin breed on upland moorland in Scotland, northern England, and Wales — on wet, boggy ground with sedge and cotton grass. These populations have declined significantly due to drainage of upland moors and overgrazing. The British breeding dunlin is a distinct subspecies (C. alpina schinzii) that is separately threatened from the abundant Scandinavian wintering population.