Species Details

Details of Greater Crested Tern will be displayed below

Greater Crested Te...   

Common Name: Crested Tern, Swift Tern
Scientific Name: Thalasseus bergii
Local Name: Bodu Gaadhooni
Dhivehi Name: ބޮޑު ގާދޫނި
Animalia  (Kingdom)
Chordata  (Plylum)
Aves  (Class)
Laridae  (Family)
Thalasseus   (Genus)

Greater Crested Tern's description

The great crested tern is a large tern with an extensive range. During the breeding season, the adult has a distinctive black cap with a long crest, white neck and underparts, and a grey back and upperwing. In contrast, the non-breeding adult has a white crown with limited dark spotting, but its hind-crown remains black. The large bill is greenish-yellow to yellow, and the legs are black. The juveniles primarily differ from the adults in having heavily mottled or barred brown upperparts.

They are found on coastlines in the south-east Atlantic Ocean, the Indian Ocean and the western Pacific Ocean. The great crested tern forages in the shallow waters of lagoons, coral reefs, estuaries, along all types of shoreline, and also far out to sea in open water. Nesting sites are usually located on offshore islands, low-lying coral reefs, coastal islets, spits, and lagoons.

The greater crested tern's closest relatives within its genus appear to be the lesser crested tern (T. bengalensis), and the royal tern (T. maximus).

Greater Crested Tern's facts

Did you know?

  • These birds have red oil droplets in the cone cells of their eyes. These droplets sharpen their distance vision and increase contrast.
  • This species has proven adaptable to humans. They have learned to follow fishing boats in order to collect jettisoned bycatch.
  • A group of terns is collectively known as a "ternery" or a "U" of terns.

Greater Crested Tern's Behavior & Ecology

The greater crested tern breeds in colonies, often in association with other seabirds. It is monogamous and the pair bond is maintained through the year and sometimes in consecutive breeding seasons.

The great crested tern feeds mostly at sea by plunge diving to a depth of up to 1 m (3.3 ft), or by dipping from the surface, and food is usually swallowed in mid-air.

Greater Crested Tern's Feeding

The diet of the great crested tern consists mainly of pelagic fish from 10 - 15 centimetres in length, but it also opportunistically takes squid, crabs, insects, baby turtles, and other aquatic prey. It typically forages in groups, flying several metres above the ocean, every now and again plunging into the water or dipping its bill just under the surface to catch unsuspecting prey. Most foraging occurs within three kilometres of the colony.

Greater Crested Tern's Reproduction

The great crested tern tends to breed in large, dense colonies or in small groups within larger mixed species colonies. Each breeding individual nests only once in any given year, with the nests being a shallow scrape in sand, gravel or coral, often packed tightly together. The clutch size is usually a singe egg, or sometimes two, which are incubated for 25 to 30 days before hatching. The chick fledges after around 38 to 40 days but remains dependent on it its parents until it is at least 4 months of age.

Greater Crested Tern's Conservation

This species is a common visitor to Maldives.

The Jack Snipe is currently classified as ‘Least Concern’ by IUCN.

Greater Crested Tern's Relationship with Humans

This is an adaptable species that has learned to follow fishing boats for jettisoned bycatch, and to use unusual nest sites such as the roofs of buildings and artificial islands in salt and sewage works. Human activities such as fishing, shooting and egg harvesting have caused local population declines.

Greater Crested Tern habitat

Behaviour Many populations remain sedentary in their breeding areas or disperse locally (del Hoyo et al. 1996), although some are more migratory (Urban et al. 1986). The species breeds in large dense colonies, or in small groups of less than 10 pairs amidst colonies of other species (e.g. King Gull Larus hartlaubii or Silver Gull Larus novaehollandiae) (del Hoyo et al. 1996). It usually forages singly (Urban et al. 1986) or in small groups (del Hoyo et al. 1996) but several hundred individuals may gather at roost sites (Langrand 1990). Habitat The species inhabits tropical and subtropical coastlines, foraging in the shallow waters of lagoons (Higgins and Davies 1996, del Hoyo et al. 1996), coral reefs (del Hoyo et al. 1996), estuaries (Urban et al. 1986, del Hoyo et al. 1996), bays, harbours and inlets (Higgins and Davies 1996), along sandy, rocky, coral (del Hoyo et al. 1996) or muddy shores, on rocky outcrops in open sea, in mangrove swamps (Langrand 1990) and also far out to sea on open water (del Hoyo et al. 1996). It shows a preference for nesting on offshore islands (Urban et al. 1986, del Hoyo et al. 1996), low-lying coral reefs, sandy or rocky coastal islets, coastal spits, lagoon mudflats (del Hoyo et al. 1996), and artificial islets in saltpans and sewage works (Urban et al. 1986, del Hoyo et al. 1996) within 3 km of the coast (del Hoyo et al. 1996). Diet Its diet consists predominantly of pelagic fish 10-50 cm long (Urban et al. 1986, del Hoyo et al. 1996) although it will also take cephalopods (e.g. squid), crustaceans (del Hoyo et al. 1996) (e.g. crabs (del Hoyo et al. 1996) and prawns (Higgins and Davies 1996)), insects and hatchling turtles opportunistically (del Hoyo et al. 1996). Breeding site The nest is a shallow scrape in bare sand, rock or coral (del Hoyo et al. 1996) in flat open sites (Urban et al. 1986) on offshore islands (Urban et al. 1986, del Hoyo et al. 1996), low-lying coral reefs, sandy or rocky coastal islets, coastal spits, lagoon mudflats (del Hoyo et al. 1996) or islets in saltpans and sewage works (Urban et al. 1986, del Hoyo et al. 1996). The species nests in dense colonies (Urban et al. 1986) with neighbouring nests very close together (rims may be touching) (del Hoyo et al. 1996), and usually forages within 3 km of the breeding colony (del Hoyo et al. 1996).

Greater Crested Tern threats

The species is vulnerable to human disturbance, which may cause the flushing of adult birds allowing increased egg predation by gulls and ibis (Gochfield et al. 2018). It may be experiencing declines in Indonesia and South Africa due to egg collection (Gochfield et al. 2018).

Greater Crested Tern's status