Dunlins are small shorebirds that are found in North America which exhibit remarkable differences between their breeding and nonbreeding plumages. In winter Dunlins exhibit drab, gray-brown plumage and gather in large flocks on coastal mudflats and estuaries.
Dunlins in their breeding plumage are much more colorful than in the winter, they were once known as “Old Red Back” and “Red-backed Sandpiper” due to the rich chestnut colored feathers on the back. They are unmistakable during breeding season because of the red on the back and the black plumage on their bellies.
Dunlins feed by probing with their bill for clams, worms, insect larvae, crustaceans, small fish and plants. They also feed in seasonal freshwater wetlands and in flooded fields. Dunlins breed in Artic and sub-Artic moist tundra near ponds and prefer drier islands for nesting sites. The nest is a simple cup shape lined with lichens, leaves and grasses where they have one brood per year with around 4 eggs.
Looking at the Dunlin images above; in breeding and nonbreeding plumage, it is almost difficult to believe they are the same species.