Black tern
Chlidonias niger
Oscar Thomas · Waikanae Estuary Scientific Reserve
Key facts in one look
- Diet
- Insects, small fish, amphibians
- Status in Georgia
- Migrant
- Recorded regions
- Kvemo Kartli
- Size
- About 25 cm, wingspan 61 cm; 62 g
- Habitat
- Lakes, marshes, reservoirs, sea coast
- Family
- Laridae
- Conservation
- Global LC (2018); Georgia LC (2024)
The black tern does not dive for fish: it flies over the water and picks food from the surface or catches insects in the air. It is about 25 cm long, with a wingspan of 61 cm, and weighs about 62 g. In summer its head, neck and belly are black, its back dark grey, its tail light brownish grey, its bill black and its legs dark. In winter the black, apart from the cap, is replaced by grey. It is harmless to people. The 2024 Georgian checklist lists it as a migrant. There are few records from Georgia, from April, May and September. Most come from Kvemo Kartli, from Kumisi Lake and Gardabani Municipality. Both globally and in Georgia it is rated Least Concern (LC).
Identification
Black tern: how to identify it
In summer it is almost entirely dark: a black head and belly and a dark grey back, wings and tail. In winter it is grey above and white below, keeps a dark cap, and has dark patches on the sides of the breast.
In breeding plumage the head, neck and belly are black. The cap is black or blackish brown and merges with the ear coverts into an almost complete hood. The back is dark grey and the tail light brownish grey and square. In some lights the plumage looks bluish.
It is about 25 cm long, with a wingspan of 61 cm, and weighs 62 g. The legs are short and dark. The bill is black and slender, 27 mm, nearly as long as the head and slightly curved. In flight it looks slim, the wingbeats are full and energetic, and the flight is often erratic. The call is a high "kik".
In winter the black, apart from the cap, is replaced by grey, and the upperparts become drab with pale feather edges. There are greyish-brown smudges on the sides of the white breast, a feature the white-winged tern lacks. There is a large dark triangular patch in front of the eye, and young birds have a fairly broad white collar.
Colour
Swatches are illustrative. Do not identify a species by colour alone.
It breeds by fresh or brackish water: small pools, lakes, marshes, ditches, quiet stretches of rivers, swampy meadows, peat bogs and rice fields. It prefers places with sparse stands of reedmace, sedge or reeds and floating water lilies, with water 1–2 m deep. It generally avoids marshes smaller than 4 hectares. On migration it stops at inland lakes, reservoirs and pools, and on the coast. In winter it lives mostly on the coast, in estuaries and lagoons, and sometimes out at sea, 400–600 km from the shore. In Georgia most records come from Kvemo Kartli: from Kumisi Lake and Gardabani Municipality, in May, and from the northern part of Tbilisi, in September. There are single records from Abkhazia, at Gagra, from Samegrelo-Zemo Svaneti and from Shida Kartli, at Nadarbazevi Lake.
The black tern map combines public iNaturalist observations. Regions are taken from the records-by-region table, and the status column separates regions with enough records from regions with too few records. Record counts reflect observation effort rather than population density. Only one region has enough records: Kvemo Kartli.
Data: Reptiles.ge + iNaturalist · Methodology
- Field observation
- Several records in one spot
- Region with records
When breeding it eats mainly insects: midges, dragonflies, mayflies and beetles, as well as small fish and amphibians, tadpoles and frogs. On migration and in winter it feeds mostly on marine fish, sometimes also taking insects and crustaceans. It does not dive for fish: it takes food on the wing, from the water surface or just above it, and catches insects in the air.
It is strongly migratory and travels both over land and over sea. Birds from Europe and Asia winter in Africa, and North American birds on the northern coasts of South America. After breeding it leaves from July and returns from late March. It lives in groups all year: when breeding, 2–20 birds feed together, and on migration and in winter large flocks gather at sea over shoals of predatory fish. It breeds in May and June in colonies, usually of fewer than 20 pairs and rarely more than 100, often close to other species. The nest is a low, flattened mound of plants in very shallow water or on floating vegetation over water more than 50 cm deep. Sometimes it is a shallow scrape on the ground among marsh plants. The female lays 2–4 eggs. It may forage 2–5 km from the breeding site.
Globally the black tern is rated Least Concern (LC, 2018). A 2015 estimate puts the world population at 800,000–1,750,000 birds, and the European one at 74,400–154,000 pairs. Overall numbers are falling, and the European trend is unknown. Because it nests on floating vegetation, the biggest threat is falling water levels, through drought and water taken for household and farm use. At low water, predators such as pigs reach the chicks more easily. Farming also takes over wetlands. In England it was abundant until the early 19th century, but after the marshes were drained it no longer bred there by about 1840. The Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies to it. The 2024 Georgian checklist also rates it Least Concern (LC) in Georgia.
Related guides
Continue with related pages
Yes. The 2024 Georgian checklist lists it as a migrant. There are few records from Georgia, from April, May and September. It spends the winter in Africa.
Most records come from Kumisi Lake and Gardabani Municipality, in May. It has also been seen near Gagra, in Samegrelo and at Nadarbazevi Lake. Look for it over lakes and marshes.
In summer by its black head, neck and belly, dark grey back, wings and tail, and dark legs. In winter it is grey above and white below, keeps a dark cap, and has dark patches on the sides of the breast. The call is a high "kik".
In summer the black tern has dark grey wings and tail and dark legs, while the white-winged tern has white wings, a white rump and red legs. In winter the black tern has dark patches on the sides of the breast and the white-winged tern does not.
When breeding, mainly insects, small fish and amphibians. On migration and in winter it eats mostly marine fish. It does not dive for fish, but takes food on the wing from the water surface.
It is harmless to people. Both globally and in Georgia it is rated Least Concern (LC), although its overall numbers are falling. The biggest threats are falling water levels in wetlands and their conversion to farmland. If you find an injured bird, call 112 or the environmental protection service.
References
What this profile is based on
Species profiles are compiled from peer-reviewed literature and established biodiversity databases, and are reviewed as new taxonomic and conservation data become available.
Prepared by the Reptiles.ge editorial team from the sources listed here.
