Black Tern

The Black Tern is a distinctive small tern of freshwater wetlands, easily recognized in summer by its striking black-and-grey plumage that sets it apart from the mostly white terns found along ocean coasts. It belongs to the group known as "marsh terns," which behave quite differently from typical sea terns.

Appearance

Breeding adults are largely sooty black on the head and underparts, with slate-grey wings and back and white undertail coverts. In non-breeding plumage and in juveniles, the bird becomes largely white below with a dark cap and a distinctive dark shoulder patch ("wrist mark").

Key field marks

• Overall black head and underparts in breeding plumage, unique among common terns
• Grey back and wings contrasting with the black body
• White undertail coverts even in breeding plumage
• Buoyant, erratic flight low over water, picking food from the surface rather than diving
• Small size and short, only slightly forked tail

Similar species

In non-breeding plumage the Black Tern resembles the Whiskered Tern and White-winged Tern, but shows a dark shoulder patch on the side of the breast and a less contrasting rump. Its buoyant, dipping feeding style over marshes also helps separate it from larger, plunge-diving sea terns.

Habitat and range

Black Terns breed across freshwater marshes, wet meadows, and shallow lakes in North America, Europe, and Asia, requiring emergent vegetation such as reeds and cattails for nesting. After breeding, they become highly migratory, moving to coastal and estuarine waters.

North American breeders winter mainly along the Pacific coast of Central and South America, while Old World populations winter along the coasts of West Africa, often gathering in large flocks over productive coastal waters.

Behavior

Unlike ocean-going terns, Black Terns rarely plunge-dive; instead they fly low with a light, erratic, almost butterfly-like flight, dipping down to pick insects and small fish directly from the water's surface or snatching flying insects out of the air.

Voice

Calls include a sharp "kik" or "kreek," given in flight, especially near the breeding colony.

Nesting and breeding

Black Terns nest in loose colonies in marshes, often building a flimsy platform nest of plant material on floating vegetation or muskrat lodges just above the waterline. They typically lay two to three eggs, and populations have declined in many areas due to loss of wetland habitat.