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North Dakota's

Federally Listed Endangered, Threatened, and Candidate Species – 1995


Black Tern (Chlidonias niger)

JPG -- species photo gif--species map

Status: Former Candidate (Note: As of February 28, 1996, this species is no longer listed as a Candidate species. However, it remains a species of management concern.)

Historical Status:
Found in Europe and Asia as well as North America. North American black terns nested in South and Central America. European and Asian birds nested in Africa. Probably historically present in all of North Dakota although uncommon in the southwest part of the state.

Present Status:
Still present in central and southern Europe and parts of Siberia. It is also still present in most of its historic range in North America, although populations appear to be greatly reduced. The black tern appears to no longer nest in California. It is present in most of its historic range in North Dakota, although it is now absent in the Red River Valley due to extensive drainage.

Habitat:
The preferred summer habitats of the black tern are inland marshes and sloughs with fairly dense cattail or other marsh vegetation and pockets of open water. In one study, 77% of the breeding pairs of black terns used what biologist call semipermanent wetlands. These wetlands are shallow in nature, they usually contain water, and they have emergent vegetation such as cattails and rushes.

Life History:
The black tern courtship ritual is elaborate with much flying. Male black terns will fly with a fish in their mouth to attract females. The black tern nests in small colonies in upland marshes and sloughs. The nest may be on a muskrat bouse or other floating mass of dead plants, usually over water 4 to 34 inches deep. The typical clutch is 3 eggs that are laid from May to early August. Incubation lasts 22 days. The successful hatching rate of nests appear to be very low. The young terns that hatch can first fly in about 24 days. Black terns breed at 2 years of age. Black terns feed on dragonflies, moths, grasshoppers, crickets, flies and many other insects as well as small fish and crustaceans. They snatch the fish and insects from the surface of the water or from nearby vegetation. Black terns can also catch certain insects such as dragonflies in mid-air. It occasionally follows plows in the hope of finding exposed grubs. The black tern is gregarious (lives in flocks) year round.

Aid to identification:
The black tern is a smallish tern averaging 9 to 10 inches long. The tail is small and only slightly notched compared to other terns. In its summer breeding plumage (appearance) the black tern has a black head and black body, with the back, tail, and wings being gray. It is the only tern with an all "black" appearance. Immature black terns and wintering adults have a white head and white underparts. The black tern calls frequently, especially when intruders are near nest. The call is a high pitch, shrill, metallic call. The flight is buoyant and erratic, with much time spent hovering 10 to 30 feet above a marsh.

Reasons for decline:
The continuing loss of habitat due to wetland drainage is the main reason for the decline in black tern populations. Reduced hatching success in the midwestern United States may be due to agricultural pesticides.

Recommendations:
Marshes and sloughs used by black terns are used on an annual basis and should be protected for the terns and their other wetland values.

Comments:
As the name implies, the black tern is related to the least tern, an endangered species. However, the two species use different habitats with the least tern restricted to the Missouri River and the black tern using upland sloughs.

References:
Breeding Birds of North Dakota by R. Stewart, 1975.


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