Species of Thailand
Thai: นกนางนวลแกลบคิ้วขาว, nok naang-nuan klaep khiu khao
Binomial name: Onychoprion anaethetus, Giovanni Antonio Scopoli, 1786
The bridled tern (Onychoprion anaethetus, formerly Sterna anaethetus - see Bridge et al., 2005) is a seabird of the tern family Sternidae. It is a bird of the tropical oceans.
This is a medium-sized tern, at 30–32 cm in length and with a 77–81 cm wingspan similar to the common tern in size, but more heavily built. The wings and deeply forked tail are long, and it has dark grey upperparts and white underparts. The forehead and eyebrows are white, as is a striking collar on the hindneck. It has black legs and bill. Juvenile bridled terns are scaly grey above and pale below.
This species is unlikely to be confused with any tern apart from the similarly dark-backed sooty tern and the spectacled tern from the Tropical Pacific. It is paler-backed than that sooty, (but not as pale as the grey-backed) and has a narrower white forehead and a pale neck collar.
Distribution and movements
This bird is migratory and dispersive, wintering more widely through the tropical oceans. It has markedly marine habits compared to most terns. The Atlantic subspecies melanopterus breeds in Mexico, the Caribbean and west Africa; other races occur around the Arabian Peninsula and in Southeast Asia and Australasia, but the exact number of valid subspecies is disputed. It is a rare vagrant to western Europe.
This species breeds in colonies on rocky islands. It nests in a ground scrape or hole and lays one egg. It feeds by plunge-diving for fish in marine environments, but will also pick from the surface like the black tern and the gull-billed tern. It usually dives directly, and not from the "stepped-hover" favoured by the Arctic tern. The offering of fish by the male to the female is part of the courtship display.
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- Onychoprion anaethetus
- English: Bridled tern
- French: Sterne bridée
- Thai: นกนางนวลแกลบคิ้วขาว, nok naang-nuan klaep khiu khao
Onychoprion anaethetus anaethetus, Scopoli, 1786
Range: Eastern Indian, and Pacific Oceans.
Onychoprion anaethetus antarcticus, René Primevère Lesson, 1831
Range: Red Sea, Persian Gulf and western Indian Ocean.
Onychoprion anaethetus melanopterus, William John Swainson, 1837
Range: Caribbean and West Africa.
Onychoprion anaethetus nelsoni, Robert Ridgway, 1919
Range: West coast of Mexico and Central America.
- Onychoprion anaethetus subspecies anaethetus, Les Christidis & Walter E. Boles (2008)
- Onychoprion anaethetus, AOU Checklist (1998)
- Sterna anaethetus, Giovanni Antonio Scopoli (1786)
Least Concern (IUCN3.1)
- Hat Chao Mai National Park
- Hat Noppharat Thara - Mu Ko Phi Phi National Park
- Khao Laem Ya National Park
- Khura Buri District, Phang Nga
- Klaeng District, Rayong
- Ko Tao
- Laem Pak Bia
- Mu Ko Lanta National Park
- Mu Ko Similan National Park
- Mu Ko Surin National Park
- Mueang Krabi District, Krabi
- Mueang Phuket District, Phuket
- Pak Thale
- Samae San Island
- Sathing Phra District, Songkhla
- Takua Pa District, Phang Nga
- Tarutao National Marine Park
- Than Sadet - Koh Pha-Ngan National Park
Range map of Onychoprion anaethetus in Thailand
Important note; our range maps are based on limited data we have collected. The data is not necessarily accurate or complete.
Special thanks to Ton Smits and Parinya Pawangkhanant for their help with many range data.
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