Greater crested tern
Large Old World tern with shaggy crest and yellow bill.
The greater crested tern (Thalasseus bergii), also called crested tern, swift tern, or great crested tern, is a large seabird in the family Laridae. It nests in dense colonies on coastlines and islands across the tropical and subtropical Old World, from South Africa around the Indian Ocean to the central Pacific and Australia. This adaptable species is notable for its distinctive appearance, including a shaggy black crest, yellow bill, and dark grey upperparts, and for its ability to use unusual nest sites such as building roofs and artificial islands.
- Scientific name
- Thalasseus bergii
- Family
- Laridae
- Subspecies
- 4 or 5
- Wingspan
- 125–130 cm
- Weight
- 325–397 g
- Population
- >500,000 individuals
- Conservation status
- No global concerns, stable
Lore & Background
All populations disperse after breeding. Southern African birds move east along the Indian Ocean coastline, while young birds may travel more than 2,000 km. The subspecies T. b. thalassinus winters on the east African coast north to Kenya and Somalia. The greater crested tern has occurred as a vagrant to Hawaii, New Zealand, North Korea, Jordan, and Israel. In India, it is protected in the PM Sayeed Marine Birds Conservation Reserve.
Reader's Guide
The greater crested tern is a significant species within its genus Thalasseus, serving as a key example of seabird adaptation to human-altered environments. Its ability to follow fishing boats for jettisoned bycatch and to nest on building roofs and artificial islands in salt pans and sewage works demonstrates remarkable behavioral flexibility. The species' stable global population of more than 500,000 individuals indicates no immediate conservation concerns, though local declines have occurred due to human activities such as fishing, shooting, and egg harvesting. Its taxonomic history, including the move from Sterna to Thalasseus based on mitochondrial DNA studies, highlights the importance of genetic research in clarifying avian relationships. The greater crested tern's distinctive plumage—darker battleship-grey upperparts, white forehead even in breeding plumage, and greenish-tinged yellow bill—helps distinguish it from closely related species like the royal tern and lesser crested tern. Its vocalizations, including a loud kerrak call, are characteristic of its breeding colonies. The species' wide distribution across the Old World tropics and its role in coastal ecosystems make it a valuable subject for ornithological study, particularly regarding colony dynamics, dispersal patterns, and responses to environmental change.
Did You Know?
- The greater crested tern's species epithet bergii commemorates Karl Heinrich Bergius, a Prussian pharmacist and botanist who collected the first specimens near Cape Town.
- Its nearest relative is the critically endangered Chinese crested tern (T. bernsteini).
- The largest documented colony, with 13,000 to 15,000 pairs, is in the Gulf of Carpentaria in northern Australia.
- This tern has occurred as a vagrant to Hawaii, New Zealand, North Korea, Jordan, and Israel.
More in Birds of the Indian Ocean 1-24
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