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ATLANTIC BROWN BOOBY  Sula leucogaster 68–75cm, WS 135–153cm.

Caribbean; mainly offshore but may be seen from land near Limón. Usually

singles or small groups, feeding or rafting on water. Slightly larger and bulkier

than Red-footed Booby, with heavier flight, less crooked wings; imm. body

darker than whitish underwing coverts (reverse of imm. and brown morph Red-

footed) and upperparts solidly brown, lacking white tail tip often shown by

imm. Red-footed. Cf. imm. Masked Booby. Adult male has yellow face, ivory to

pale greenish bill; female has pale yellow face, pinkish bill. SOUNDS: Male gives

high wheezy whistles, female gruff brays. STATUS: Uncommon in Caribbean

waters; small colony on islets near Uvita I. (Tropical Atlantic.)

RED-FOOTED BOOBY  Sula sula 66–76cm, WS 130–150cm. Pacific and

Caribbean, offshore; only exceptionally seen from land. Mostly alone or with

feeding flocks of other boobies, terns, shearwaters; often curious around boats

and ships, roosts on rigging. Smallest, most lightly built booby with highly

variable plumage. Diagnostic bright red feet develop in 2nd year, pinkish on

juv. (rarely pinkish on juv. brown boobies). Note crooked wings, long tail,

maneuverable flight. Imm. and brown morph told from brown boobies by

structure, paler body contrasting with dark underwings; imm. bill often pinkish

with dark tip, tail usually has white tip. On all adults note pale bluish bill, pink

throat patch. White-tailed morphs occur in Caribbean, dark-tailed morphs in Pacific; Cocos I. population

almost all brown morphs. Cf. adult Masked and Nazca Boobies. STATUS: Uncommon to fairly common

year-round in Pacific waters, usually well offshore; birds over nearer shore waters mainly imms; small

colony found in 2000s on inshore islet near mouth of Sierpe River (and breeds commonly on Cocos I.).

Very rare on Caribbean coast (mainly storm-blown). (Tropical oceans worldwide.)

TROPICBIRDS (PHAETHONTIDAE; 1+ SPECIES) Small family of spectacular

plunge-diving seabirds found worldwide in tropical oceans. Ages differ, sexes similar; adult

appearance attained in about 2 years.

RED-BILLED TROPICBIRD  Phaethon aethereus 43–50cm (+ streamers), WS

97–110cm. Pacific, offshore. Spectacular, heavy-bodied oceanic bird, overall

gleaming white with black leading wedge to outer wing, narrow dark barring on

back. Cf. Royal Tern (p. 54). Flies with hurried, ungraceful wingbeats and

plunge-dives from high up, causing a ‘whale-blow splash’ of water. Often rests

on water, tail streamers curved up like a rooster; at times attracted to boats

and ships, when appears magically overhead then disappears. Adult has red

bill, long tail streamers; juv. has yellowish bill, short tail tipped black. 2nd-year

like adult with orange-red bill, shorter tail streamers. Mostly silent at sea.

STATUS: Uncommon nonbr. visitor year-round to Pacific waters, usually well offshore; may also occur

rarely off Caribbean coast. (Tropical Americas and Atlantic.)