Medium. Slender, with a long forked tail and long thin black bill. Sexes alike.
Adults: Almost completely with, except for a sharp black band from lores, through eye, continuing to black crest on nape. Eye, dark brown. Back, wings, very pale grey, almost white, with outer web of outer primaries black. Bill, black, often with a yellow tip. Legs, black.
Immatures: Like adult but black band through eye to nape less distinct. Eye, dark brown. Crown, back, wings, speckled with black, outer primaries dark grey, almost black. Lacks long outer tail feathers. Bill, yelowish to blackish. Legs, black.
Nest
A depression in coral fragments or sand, on a beach, just above the high water mark. In colonies.
Eggs (Guide)
2; matt, stone-grey, spotted with brown and dark grey; ellipsoidal; about 39 x 29 mm. Incubation: about 25 days; by both sexes.
Young
Precocial, semi-nidifugous. Fledge in 21 - 23 days.
Subspecies
Thought to be closely related to Roseate Tern (Sterna dougallii), with which sometimes nests, but chick pattern very different. Sometimes considered monotypic, but divided into subspecies on basis of shape.
The following 2 subspecies are recognised:
sumatrana Raffles, 1822 - Andaman and Nicobar Is east to southern Japan and China, and south through Malaysia, Philippines, Indonesia and New Guinea to north-eastern and eastern Australia and Pacific islands (Yap, Marshall Is, Ponapé, Micronesia), with breeding also suspected (at least formerly) in Bengal, Bangladesh and southern Myanmar. Birds from Japan and China winter to south.
mathewsi Stresemann, 1914 - Aldabra, Amirante, Chagos and Maldive Is, western Indian Ocean.
Similar Species
Little Tern (Sternula albifrons)
Much smaller. Non-breeding and immature with non-breeding and immature. Greyer above, has a dark shoulder mark and dark flight feathers. Wing beats are quicker.
Roseate Tern (Sterna dougallii)
Larger. Non-breeding with non-breeding. Greyer above, has a longer black nape and grey shoulder bar. Legs are orange-red.
Compare Images
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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