Black Tern

Overview

The Black Tern is a small, marsh-breeding tern notable for its unusual breeding plumage, in which the head, neck, and underparts become sooty black, contrasting with paler gray wings, back, and tail. This pattern sets it apart strikingly from most other terns, which retain white underparts year-round, and makes breeding adults some of the most distinctive terns to identify. Outside the breeding season the species transitions to a much more typically pied pattern, with white underparts and a dark cap and ear patch, resembling other small terns more closely at that time of year.

Unlike many terns that nest on open sand or gravel, the Black Tern breeds in freshwater marshes, building floating nests among emergent vegetation, a habitat association shared with only a small number of other tern species.

Feather Identification

• Body feathers: In breeding plumage, head, neck, and underparts are sooty black, a pattern essentially unique among regularly encountered terns and unmistakable when present.
• Wing and tail feathers: Pale to medium gray, contrasting with the black body in breeding adults; in nonbreeding and juvenile plumage the gray tone extends across the back as well, with white underparts replacing the black.
• Size and shape: Feathers are small and light, consistent with the species' small body size and buoyant, fluttering flight over marshes and open water.
• Compared to similar species: No other common tern shows an entirely black body in breeding plumage; in nonbreeding plumage, the combination of a dark cap, dark ear patch, and grayish wash on the sides of the breast helps distinguish it from small Sterna and Sternula terns, which typically show cleaner white underparts without the dark shoulder patch.

Plumage Details

Breeding adults show a sooty black head, neck, and underparts, with pale to medium gray wings, back, and tail, and a black bill. In nonbreeding plumage the black is lost, replaced by white underparts, a dark cap, and a dark patch on the side of the breast near the shoulder, along with a grayish wash on the back. Juveniles resemble nonbreeding adults but show a scaly, brownish tinge to the back and covert feathers, gradually molting to the grayer adult-type plumage. The transition between the black breeding plumage and the pied nonbreeding plumage occurs relatively quickly, making transitional, patchily black-and-white individuals a common sight in late summer.

Habitat & Range

Black Terns breed in freshwater marshes, wet meadows, and shallow wetlands with abundant emergent vegetation across much of the northern United States, Canada, and parts of Eurasia. Outside the breeding season the species becomes more coastal and even pelagic in places, migrating to wintering grounds along the coasts of Central and South America and parts of Africa for Old World populations. Migration often takes birds well offshore or over large lakes, differing from the mostly coastal or marsh-restricted habits of the breeding season.

Behavior & Field Notes

Black Terns forage largely on flying insects taken on the wing over marshes and open water, as well as small fish and aquatic invertebrates picked from the surface, a more insectivorous diet than many other terns. They nest in loose colonies on floating mats of marsh vegetation, muskrat houses, or similar platforms just above the water surface. The call is a sharp, metallic "kik" or "kreek" note. Its buoyant, erratic flight low over marshes, combined with the striking black breeding plumage, make this one of the more distinctive terns of freshwater wetlands in summer.