Large. Short crest, long decurved bill, medium long forked tail. Sexes alike.
Adults: Breeding: Shaggy black cap, separated fom bill by a white saddle. Crest is short. Forehead, sides of face, underparts, white. Rest of upperparts, grey. Outer primaries have black inner webs and distinct white shafts. Eye, dark brown. Bill, pale yellow. Legs, black. Non-breeding: Like breeding plumage but crown streaked black and white. Bill, pale yellow. Legs, black.
Immatures: Similar to non-breeding adult but face and crown streaked black and buff. Back, wing coverts have some dark brown feathers and feathers are tipped white. Primaries, tail feathers, dark grey edged and tipped with white. Bill, brownish-yellow with a dark tip. Legs, black.
Other Scientific Names
Thalasseus bergii [Christidis and Boles (2008)], Thalasseus bergii [AOU checklist (1998 + supplements)]
Other Names (World)
Greater Crested Tern, Greater Crested-Tern, Great Crested-Tern, Great Crested Tern, Swift Tern, Bass Straits Tern, Torres Straits Tern, Yellow-billed Tern, Diver
Australia (B), Bahrain (NB), Bangladesh, British Indian Ocean Territory, Brunei Darussalam, Cambodia, China (mainland), Cook Islands (B), Djibouti (B), Egypt, Eritrea, Fiji (B), French Polynesia, Guam (B) (NB), India, Indonesia, Iran [Islamic Republic of] (P), Iraq (NB), Israel, Japan, Kenya, Kiribati, Kuwait, Madagascar (B), Malaysia (B), Maldives (B), Marshall Islands (B), Mauritius, Mayotte, Micronesia [Federated States of] (B) (NB), Mozambique, Myanmar, Namibia (B), New Caledonia (B), Northern Mariana Islands (NB), Oman (B) (NB) (P), Pakistan, Palau (B), Papua New Guinea (B), Philippines (B), Qatar, Saudi Arabia (B), Seychelles (B), Singapore, Solomon Islands (B), Somalia, South Africa (B), Sri Lanka, Sudan (B), Taiwan (China) (B), Tanzania [United Republic of] (B), Thailand, Timor-Leste (B) (NB), Tonga (B), Tuvalu (B), United Arab Emirates, Vanuatu (B), Vietnam, Wallis and Futuna Islands, Yemen (NB) (P).
Vagrant to Jordan, Nauru, New Zealand, North Korea, USA.
Population
Estimated population is 150,000 - 1,100,000 (2010).
Status LC
Human disturbance at its breeding colonies, mortality from entanglement with fishing lines, baited hooks and humand refuse, are the main threats.
For more information see BirdLife International Species Factsheet.
Habits
Singly or in small flocks. Often perches on poles and other debris in water. Feeds by diving head first into water.
Food
Mainly fish procured by diving. Occasionally prawns and squid.
Voice
A rasping, 'carrik' or 'kiirik', a purring 'kr r ra a ar', a hard rattling 'skroach'. Calls alone and in duet.
Greater Crested Tern (Thalasseus bergii) [XC214467]
by Marc Anderson from Werribee Treatment Plant, Victoria, Australia (call)
Greater Crested Tern (Thalasseus bergii) [XC368836]
by Drew Davison from Utungake, Vava'u, Tonga (flight call)
Nest
A depression in sand or earth. In large colonies.
Eggs (Guide)
1, rarely 2; slightly glossy, stone-grey with sepia, red-brown and black streaks; oval; about 61 x 41 mm. Incubation: about 25 - 26 days; by both sexes.
Young
Precocial, semi-nidifugous.
Subspecies
Sometimes considered to form superspecies with Royal Tern (Thalasseus maximus).
Subspecific taxonomy unusually confusing, with many other subspecies proposed, e.g. bakeri, edwardsi, halodramus, pelecanoides, poliocercua. Subspecies gwendolenae may not be valid.
The following 6 subspecies are recognised:
bergii (Lichtenstein, 1823) - Namibia to South Africa; some non-breeders move to southern Mozambique.
cristatus (Stephens, 1826) - Malaysia to Philippines and Ryukyu Is, and eastern Australia to Society Is.
thalassinus Stresemann, 1914 - Tanzania, Seychelles, Aldabra and Rodrigues I, and possibly this subspecies in north-western Madagascar; wanders to southern Somalia.
velox (Cretzschmar, 1827) - Red Sea and north-western Somalia east to Myanmar, Maldives and Sri Lanka; western populations winter south to Kenya.
enigma (Clancey, 1979) - Zambezi Delta, believed to nest on islands off Mozambique and Madagascar.
gwendolenae (Mathews, 1912) - Western and north-western Australia.
The Field Guide to the Birds of Australia Pizzey, G., and Knight, E., 1997, Angus & Robertson, Sydney ISBN 0 207 19691 5
Field Guide to Australian Birds Morecombe, M., 2000, Steve Parish Publishing Pty Ltd. ISBN 1 876282 10 X
Field Guide to the Birds of Australia Simpson, K., and Day, N., 1999, 6th Edition, Viking ISBN 0 670 87918 5
Reader's Digest Complete Book of Australian Birds 1988, 2nd Edition, Reader's Digest ISBN 0 949819 99 9
What Bird is That? 1984, Revised Edition, Angus & Robertson, Sydney ISBN 0 207 14846 5
Handbook of Australian, New Zealand & Antarctic Birds 1990 - , Oxford University Press, Melbourne ISBN 0 19 553244 9
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BirdLife International Species Factsheet