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PLATE 55: LARGER TERNS
Gull-billed Tern Gelochelidon nilotica PM, WV
L: 38. W: 95. Medium-sized tern somewhat resembling Sandwich Tern but lacks crest and has
shorter, thicker, gull-like all-black bill, shallower forked tail and whitish-grey rump and tail
(white in Sandwich); lacks contrast shown by Sandwich Tern between dark outer and pale inner
primaries above; outer primaries have distinct dark trailing edge. In winter, lacks black cap but
has variable black ‘mask’, behind eye. Juvenile is much less spotted on scapulars and innerwing-
coverts than similar Sandwich, and has white crown and black eye-patch, recalling winter adult
Mediterranean Gull; in first-winter head even whiter. Flight more leisurely and aerobatic than
Sandwich. When standing, note more robust build with long black legs. Feeds over fields, marshes,
dipping to surface. Voice Nasal ger-wek with stress on second syllable; alarm fast, agitated, nasal
laughing notes dididit; juvenile call soft pre-eep. Habitat Sheltered coasts, inland waters; nests
colonially. Note Passage hatched; winters mainly Iran and S Arabia.Caspian Tern Hydroprogne caspia PM, WV
L: 53. W: 135. Near size of a large gull, identified by large red bill, almost gull-like flight with slow
steady wingbeats and by call; distinctive dark primaries below. Juvenile has orangey bill, more
extensive black cap to below eye (unlike adult), weak dark scales on mantle and wing-coverts,
primaries dark both above and below; legs pale (black in adult). Voice Deep, loud, harsh and
deliberate aark, recalling Grey Heron, or longer retching kraa-jak. Habitat Open coasts, lagoons;
inland wetlands; nests in winter in Arabian Gulf, singly or colonially on small islands. Note Passage
hatched; winters mainly in Arabia.Greater Crested Tern Thalasseus bergii RB, PM, WV
L: 46. W: 105. Large, between Sandwich and Caspian Terns in size. Adult from smaller Lesser
Crested Tern by longer, thicker, more drooping, waxy greenish-yellow bill and by darker grey
upperparts, with rump and tail paler grey than back; tail slightly longer, more forked, and wings
broader than Lesser Crested. In summer, black crested cap always broken by white forehead-
band (never black as in some Lesser Crested). In winter, bill paler greenish-yellow, or washed-out
yellowish-orange; crown white with black confined to nape; tail and rump almost as dark as back.
Juvenile has pale innerwing-panel above, framed by dark bar on forewing and dark covert- and
secondary bars. Flies with shallow, deliberate wingbeats. Voice Deep, rough, kee-rit, or gravelly
craark; also a high-pitched kree-kree. Habitat Coastal; nests colonially on sandy or rocky islands.
Note Disperses to hatched areas. [Alt: Swift Tern]Lesser Crested Tern Thalasseus bengalensis PM, WV
L: 41. W: 92. Size as Sandwich Tern. Long, slim orange-yellow bill, upperparts pale ash-grey,
with rump and tail paler grey. Crested nape black; forehead in summer is white or black. In winter
bill paler orange-yellow; solid black confined to nape. Juvenile has bill paler orange than adult;
resembles juvenile Swift Tern but upperwing has paler dark bands and less pronounced pale mid-
wing panel; dark markings on inner wing retained to first spring as are dark primaries above. Told
from Sandwich Tern by bill colour and slightly darker upperparts. Voice Recalls Sandwich Tern
closely, but less grating and not so obviously disyllabic, krriik-krriik or kreet-kreet; also kir-eep and
kee-kee-kee; juvenile call much as juvenile Sandwich Tern. Habitat Coastal; nests colonially on
sandy or rocky shores or islands. Note Disperses to hatched areas.Sandwich Tern Thalasseus sandvicensis PM, WV
L: 41. W: 92. Medium-sized with pale grey upperparts and wings (which may look almost white at
sea), long slender black bill tipped yellow (yellow tip hard to see at distance), long narrow wings,
medium-short forked tail and fairly long neck in flight, which is powerful with deep wingbeats. In
summer black cap has ragged crest; in winter, black confined to nape extending forward to eye (like
Lesser Crested Tern). Juvenile has all-black bill, dark-scaled mantle and forewing-coverts, but lacks
the broad dark bars on inner wing of similar-aged Lesser Crested; first-winter has grey mantle and
scapulars and head pattern like winter adult. Voice Loud, grating disyllabic kerr-rick; juvenile’s call
heard into winter, high-pitched k-rill. Habitat Coastal. Note Passage and winter hatched; many
non-breeders oversummer.