Appearance
A small tern with a light, graceful appearance in flight. Breeding adults have black heads and bellies, with grey wings and tail.
Size
Length 22–26 cm, wingspan 56–62 cm, weight 60–75 g.
Nest
Among aquatic vegetation, sometimes in an abandoned grebes’ nest; made of loosely piled up aquatic plant material.
Breeding
2–3 eggs laid May–June, incubated by both parents for 20–23 days. Young able to fly within 20–23 days.
Distribution
Scarce breeder in freshwater wetlands, found as far north as Oulu. Finnish population estimated at 15–25 pairs.
Migration
Autumn migration July–September, returns in May. Winters in western and southern Africa.
Diet
Insects, invertebrates.
Calls
A harsh “kit”, and a slightly nasal “kyie, kyie”.
Endangerment
Critically endangered, protected in Finland. Globally Least concern.

In their summer plumage, adult Black Terns have sooty black heads and underparts, with the exception of pale grey vents. Their backs, tails, rumps and wings are grey. Young birds have grey upper parts with brown tips to their feathers. Their underparts, foreheads and necks are white, but other parts of their head have dark markings. Black Terns’ legs are reddish brown (adults) or yellowish (juveniles). Mature birds have black beaks, young birds have dark beaks with yellow bases to the lower mandible. Their irises are dark brown.

A similar species, the White-winged Black Tern (C. leucopterus), can occasionally be seen in Finland. This species has a shorter beak, longer legs, broader wings and a less forked tail than the Black Tern. White-winged Black Terns are most easily distinguished from Black Terns by their white tails and the different colouring on the leading edge of their wings: white above and black below.

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