Birds
Dunlin
Calidris alpina · also called dunlins
Over a vast tidal mudflat, thousands of dunlins lift off as one and twist through the air in a single shifting shape, a living cloud coordinated closely enough that no individual bird ever seems to break formation.
Overview
The dunlin, Calidris alpina, is an abundant small shorebird that breeds on Arctic tundra and winters across coastal mudflats and estuaries worldwide. Its bold black-bellied breeding plumage and habit of forming vast, tightly synchronised winter flocks make it one of the more visually striking and genuinely abundant shorebirds anywhere on Earth.
Safety measured in numbers
A lone dunlin would stand little chance against a diving falcon, but a flock of thousands moving as a single coordinated shape turns that same vulnerability into one of the more effective group defences found among any migratory bird.
Status
Least Concern — widespread and abundant across suitable Arctic breeding and coastal wintering habitat, though some regional wetland stopover sites face degradation.
Dunlin: common questions
Why do dunlin flocks move in such tightly coordinated swirls?
Dunlins gather in enormous flocks outside the breeding season and perform swirling, tightly coordinated aerial manoeuvres over mudflats and estuaries, a behaviour thought to help confuse and deter predators such as falcons, since a shifting mass of thousands of birds is far harder to single out an individual from than a small, loose group.
How does a dunlin find food hidden in the mud?
A dunlin has a slightly downcurved bill tip well suited to probing deep into soft mud and sand, using touch-sensitive nerve endings near the bill's tip to detect buried invertebrates without needing to see them directly, an adaptation shared broadly among probing shorebirds.
What does a breeding dunlin look like?
A breeding dunlin displays a distinctive solid black belly patch set against a rusty-red back, a striking and fairly easily recognised seasonal plumage that fades into a much plainer grey-brown pattern once the bird moves into its non-breeding winter plumage.
Where does the dunlin breed and winter?
A dunlin breeds on open Arctic tundra across the far north, nesting directly on the ground, then migrates to coastal mudflats, estuaries, and beaches across temperate and subtropical regions on multiple continents for the winter.