Greater Crested Tern

Identification

The greater crested tern is a large tern, measuring 46–49 cm in length with a wing-span of 125–130 cm. It is distinguished by its dark grey upperparts, white underparts, and a striking glossy black shaggy crest. The most reliable identifying feature is its greenish-tinged yellow bill, which sets it apart from related species that have orange or black bills. In breeding plumage, the forehead remains white even when the rest of the crown is black—a characteristic that helps separate it from some similar species.

In winter, the upperparts fade to a paler grey and the crown becomes predominantly white, with the crest reduced to a peppered pattern. Juvenile birds are particularly distinctive, with strongly patterned grey, brown, and white plumage on the upperparts and dark barring on closed wings. Adults of both sexes are identical in appearance. The greater crested tern is 25% larger than the similar lesser crested tern, with a proportionately longer bill and heavier head.

Range & Habitat

The greater crested tern occurs across tropical and warm temperate coastal regions of the Old World, from South Africa around the Indian Ocean to the central Pacific and Australia. Four or five geographical subspecies are recognized, with breeding populations distributed throughout this vast range. All populations disperse widely from their breeding grounds after nesting concludes.

This tern nests in dense colonies on coastlines and islands. It is a highly adaptable species that has learned to use unusual nest sites such as roofs of buildings and artificial islands in salt pans and sewage works, in addition to traditional coastal and island locations. The species typically inhabits marine environments where it can hunt effectively.

Behaviour & Diet

Like all members of the genus Thalasseus, the greater crested tern feeds by plunge diving for fish in marine environments. It has demonstrated remarkable adaptability by learning to follow fishing boats to scavenge jettisoned bycatch. The species is highly vocal, especially at breeding grounds, with calls including a loud, raucous, crow-like "kerrak" used for territorial advertisement, a "korrkorrkorr" given at the nest by anxious or excited birds, and a hard "wep wep" in flight.

Males play an important role in courtship by offering fish to females. Young terns remain dependent on their parents for food for several months after fledging. Despite its success, the species faces predation from gulls and ibises, which take eggs and young birds. The greater crested tern maintains a stable global population of more than 500,000 individuals with no global conservation concerns.

Best Time & Places to See It

Breeding seasons vary by subspecies and location. Northern subspecies breed from May to September or October, while southern African subspecies breed from December to April. Australian and Pacific populations breed from September to about April, whereas birds in Southeast Asia breed from February to June or July. Birds can be found year-round throughout their range, as populations disperse widely after breeding.

Look for greater crested terns along coastlines and around islands throughout the tropical and subtropical Old World, from South Africa eastward around the Indian Ocean to Australia and the central Pacific. They are often seen hunting in marine environments and may be found associating with lesser crested terns and other seabird species. Fishing harbors and coastal areas with active fishing activity may offer excellent viewing opportunities as the species scavenges bycatch.

Photography Tips

The greater crested tern's large size and distinctive plumage make it a rewarding photography subject. The contrast between its dark grey upperparts and white underparts provides good tonal range. Capture the bird's characteristic yellow bill and shaggy black crest, which are diagnostic field marks. Birds in breeding plumage offer the best visual impact, with the sharp contrast between the white forehead and black crown being particularly striking.

Plunge-diving sequences offer dramatic photographic opportunities; position yourself to capture the bird entering the water for fish. Breeding colonies provide excellent opportunities for behavior shots, including courtship displays where males offer fish to females, and territorial interactions. Young birds in their distinctive variegated plumage are also worth photographing. Early morning or late afternoon light will enhance the tern's colors and texture, particularly the glossy finish of the crest.