Christmas Island Frigatebird Fregata andrewsi Scientific name definitions

89–100 cm; male c. 1400 g, female c. 1550 g; wingspan 205–230 cm. Male has blackish-brown plumage, blacker and glossed green or bluish green on head , neck mantle and scapulars; most of upperwing-coverts with broad pale brownish fringes forming a usually bold pale diagonal panel; browner underside to greater coverts and remiges contrasting slightly with blackish rest of wing; diagnostic white patch on belly not reaching vent or axillaries, but may have (younger adults?) a few isolated white feathers on outer axillaries, rest often tipped light brownish; iris and narrow bare eyering blackish; bill dark grey to bluish grey with pinkish rim at base (subadult?); gular pouch bright red, much smaller and duller in non-breeding season; legs slate-grey. Female differs in having little or no gloss to upperparts, abdominal white reaches to rear belly, most of breast, collar on side of neck, over central axillaries, and can have a few white lesser coverts forming distinct spot on innermost upperwing; eyering, bill, gular pouch and legs flesh-pink. Juvenile  has whitish head  , nape and down to central breast, with strong apricot to rusty tinge; otherwise generally dark brown above, with paler brown fringes to mantle and scapulars, upperwing blacker on remiges, primary-coverts and inner marginal and lesser coverts, marginal coverts on carpal area and most of lesser coverts browner and broadly fringed pale brown to whitish forming bold panel, and may have a few white feathers forming white spot on innermost upperwing; sides of breast and narrow band across lower breast dark brown, belly white extending to central flanks and often to central axillaries; eyering, bill and legs pale bluish grey to pale pinkish flesh. With age, females become whiter on lower breast, progressively attaining adult plumage; immature male has blotchy neck and breast, looking somewhat intermediate between adult male and female. Large frigatebird; adult male with diagnostic shield-shaped white abdomen differs from F. ariel, the only other adult male frigatebird with white on underparts, by white on central belly, not on central flanks and axillaries, also by larger size and upperwing panel. Adult female has bold white collar resembling smaller F. ariel in this respect, and differs from all other female frigatebirds in having noticeably more extensively white underparts, including belly, white spur on axillaries rather angled extending sideways from about midway along white abdominal region and enhanced by dark patch just below leading edge of wing. Pale-morph female F. aquila is also white-bellied, but has light bluish eyering and broad brown pectoral band, thus white spur on axillaries emanates from anterior portion rather than from middle of white abdominal region. Juvenile can resemble those of F. minor and F. ariel, but latter has characteristic white ventral patch and is smaller overall, while former usually has less dark on breast-sides.

Known to breed only on Christmas I, in E Indian Ocean; forages in surrounding ocean and disperses widely, mainly in Indo-Malay Archipelago over the Sunda Shelf to South China Sea, Andaman Sea, Gulf of Thailand, Sulu Sea and off SW Sulawesi. Said to breed on Anambas Is, E of Malay Peninsula, but good evidence lacking.

Nests in tall trees, especially Indian almond (Terminalia catappa), preferably where sheltered from SE trade winds; nests and roosts in rain forest mostly on outer part of shore terrace, not far from human habitation, also phosphate dryers and golf course. Feeds in high temperature, low salinity waters of surrounding ocean, mainly in pelagic zone.

There is evidence that breeders frequently forage 100s or even 1000s of km from their colonies. In particular, a satellite-tracked female with a large chick undertook a non-stop 26-day and 4000 km return flight from Christmas I via Sumatra and Borneo (1 James, D. (2006). Secrets of Christmas seabird revealed. World Birdwatch. 28(1). Close ). Breeders and non-breeders have been recorded foraging at low densities in Indo-Malay Archipelago (including the Singapore Strait) (2 Poole, C.M., Davison, G.W.H. and Rajathurai, S. (2014). Marine surveys to study the movements of seabirds through the Singapore Strait 289189–28913. Forktail. 30: 5–9. Close ), over the Sunda Shelf to S China Sea, Andaman Sea, Sulu Sea, off SW Sulawesi and Gulf of Thailand, with one record from West Timor (Jul 1985) (3 Trainor, C.R. and Hidayat, O. (2014). Kupang Bay: an internationally significant wetland in West Timor, Indonesia. BirdingASIA. 21: 45–50. Close ). Post-breeding, females and dependent immatures especially, disperse N to S China Sea, where concentrations reported at roosting islands off NW Borneo, notably Mantanai and Pulua Tiga (4 Phillipps, Q., and K. Phillipps (2011). Phillipps’ Field Guide to the Birds of Borneo. Sabah, Sarawak, Brunei and Kalimantan. Second edition. John Beaufoy Publishing Ltd, Oxford, UK. Close ). A few birds of all ages also reported from the reef systems of C & S Sulu Sea, along the Cagayan Ridge (Philippines), where first recorded in 1995 and total of 161 individuals recorded to date (5 Jensen, A. E., T. H. Fisher, and R. O. Hutchinson (2015). Notable new bird records from the Philippines. Forktail 31:24–36. Close ); they join the larger numbers of F. minor and F. ariel attracted by breeding Red-footed (Sula sula) and Brown Boobies (S. leucogaster). Some numbers have also been reported from Jakarta Bay, W Java, during a Jul–Oct survey, with peak counts of > 200 birds in Sept (6 Noni, F. (2012). Conservation of Christmas Island Frigatebird Fregata andrewsi in West Java, Indonesia – mid-term report. BirdingASIA. 17: 101–103. Close ). Status in Indian Ocean W of Australia is not well known but has been found to range more than 700 km S of Chistmas I in Apr (7 Dunlop, J.N., Surman, C.A. and Wooller, R.D. (2001). The marine distribution of seabirds from Christmas Island, Indian Ocean. Emu. 101(1): 19–24. Close ). There are also two sight records from S New Guinea (neither authenticated) (8 Beehler, B. M., and T. K. Pratt (2016) Birds of New Guinea: distribution, taxonomy, and systematics. Princeton University Press, Princeton, New Jersey. Close ) and others in Melanesia (an adult female off New Georgia in Jul 1990 and five males roosting on Rennell I in Sept 1990 (9 Dutson, G. (2001). New distributional ranges for Melanesian birds. Emu. 101(3): 237–248. Close ), but neither considered to be confirmed) (10 Dutson, G. (2011). Birds of Melanesia: The Bismarcks, Solomons, Vanuatu and New Caledonia. Christopher Helm, London, UK. Close ). Vagrants have reached N Australia (Darwin) (11 McMaster, D., Thomas, S., Rayner, T.S. and McMaster, C.A. (2015). Additional records of Christmas Frigatebird Fregata andrewsi in the Northern Territory, Australia. Australian Field Orn.. 32(3): 113–117. Close ), Kenya, Hong Kong, with at least one record in India (12 Praveen, J., R. Jayapal, and A. Pittie (2013). Notes on Indian rarities–1: Seabirds. Indian Birds 8(5):113–125. Close ) and several possible sightings from the Chagos archipelago (13 Carr, P. (2015). Birds of the British Indian Ocean Territory, Chagos archipelago, central Indian Ocean. Indian Birds 10(3–4):57–70. Close ). Recorded once in Kenya: one, possibly two birds photographed near Malindi Dec 1969–Jan 1970 (14 Fisher, D., and N. Hunter (2016). East African Rarities Committee Report 2013–2015. Scopus 36(2):57–64. Close ).

Little known. Mostly flying-fish and squid; also seabird eggs and chicks, carrion and even grasshoppers recorded. Surface-dipping and, probably to a lesser extent, kleptoparasitism main systems for obtaining food, with targets of the latter including Red-footed (Sula sula) and Abbott’s Boobies (Papasula abbotti), Red-tailed (Phaethon rubricauda) and White-tailed Tropicbirds (P. lepturus), and Brown Noddy (Anous stolidus) around Christmas I, but in Jakarta Bay, Indonesia, also Grey Heron (Ardea cinerea), Black-crowned Night-heron (Nycticorax nycticorax), Striated Heron (Butorides striata), Cattle Egret (Bubulcus ibis), Oriental Darter (Anhinga melanogaster) and a tern sp. during non-breeding season (15 Tirtaningtyas, F.N. (2014). Kleptoparasitic behaviour of Christmas Island Frigatebirds Fregata andrewsi in Jakarta Bay, Indonesia. BirdingASIA. 21: 66–67. Close ).

Usually silent away from breeding colonies. Calls  at nest include plaintive, nasal calls, such as “kyeah...kyeah...kyeah” prior to landing, occasionally followed on landing by a peculiar wavering “kyoh-ee-oh-ee-oh-ee-oh-ah”. Courtship warble, with gular sac fully inflated, a low-pitched and slow “oo-aw...oo-aw”, directed at females in flight. Also mechanical bill-clapping  . Young beg with porcine squealing (16 Nelson, J. B. (2005). Pelicans, Cormorants and their relatives. Pelecanidae, Sulidae, Phalacrocoracidae, Anhingidae, Fregatidae, Phaethontidae. Oxford University Press, New York. Close ).

Lays mostly Mar–May. Breeding biennial, when successful. Loose colonies, usually in nuclei of 10–20 pairs; up to 38 nests in same tree; some overlap with F. minor. Nest a flimsy stick platform, c. 50 cm wide, 10–20 m up in fork of tree. Single egg; incubation c. 50–54 days; chicks naked, grow white down; fledging normally 19–24 weeks; post-fledging care c. 5–10 months, maximum recorded 15. Sexual maturity at 5–7 years or more. Estimated 30% of eggs laid result in independent young. Most nests comprise a single colony, making the species particularly vulnerable to cyclones or forest fires (17 Chambers, L.E., Devney, C.A., Congdon, B.C., Woehler, E.J. and Dann, P. (2011). Observed and predicted effects of climate on Australian seabirds. Emu. 111(3): 235–251. Close ).

CRITICALLY ENDANGERED. CITES I. Previously considered Endangered.  In 2003, global population put at 2400–4800 mature individuals, roughly equivalent to 3600–7200 individuals in total. Individuals only nest in alternate years: 1171 pairs were found nesting in 2003. Has declined following large-scale habitat destruction of rainforest by phosphate mining. Historically, the population was estimated at 6300 pairs nesting per year but following human settlement numbers fell to 4500 by 1910, 3500 by 1945, 2500 by 1967 and 1500 by 1978. Up to 186 individuals have been recorded in Jakarta Bay, Java (Indonesia) during year-round surveys in 2011 to 2013 (15 Tirtaningtyas, F.N. (2014). Kleptoparasitic behaviour of Christmas Island Frigatebirds Fregata andrewsi in Jakarta Bay, Indonesia. BirdingASIA. 21: 66–67. Close ) and 500 roosting on Mantanani Is (Sabah) in Oct 2012 (18 Robson, C. (2014). From the field. BirdingASIA. 21:121–127. Close ). Original threats included hunting. Cylones also destroy many nests in some seasons. More recently, the introduction of the alien yellow crazy ant (Anoplolepis gracilipes) to the island has had serious effects on the local ecology: the ants kill the red land crabs (Gecaroidea natalis) and cultivate scale insects that damage trees; however, no direct impact on frigatebirds has yet been noted. Threats away from breeding sites may have also some importance: in Jakarta Bay they include accidental entanglement in fishing gear, capture, poisoning and shooting (19 Tirtaningtyas, F.N. and Hennicke, J.C. (2015). Threats to the critically endangered Christmas Island Frigatebird Fregata andrewsi in Jakarta Bay, Indonesia, and implications for reconsidering conservation priorities. Marine Orn.. 43(2): 137–140. Close ).