Lesser frigatebird
Smallest frigatebird, found across tropical oceans worldwide.
The lesser frigatebird (Fregata ariel) is the smallest member of the frigatebird family, measuring about 75 cm (30 in) in length. It ranges across tropical and subtropical waters of the Indian and Pacific Oceans, and also appears off Brazil’s Atlantic coast. This seabird has a light build, brownish-black feathers, long narrow wings, and a deeply forked tail. Males display a vivid red throat pouch, which they puff up to draw in a mate. Females are slightly larger, with a white chest and belly. Frigatebirds catch fish, especially flying fish, from the ocean’s surface while in flight, and sometimes steal food by harassing other birds until they vomit their catch.
English zoologist George Gray first described the species in 1845 as *Atagen ariel*, based on a specimen from Raine Island, Queensland, Australia. It is one of five closely related species in the genus *Fregata*, alongside the great, Christmas, magnificent, and Ascension frigatebirds. This genus is the sole member of the family Fregatidae.
Three subspecies are recognized. *F. a. ariel* lives in the central and eastern Indian Ocean, seas around Southeast Asia, and from northern Australia to the west and central Pacific. *F. a. iredalei*, named by Australian ornithologist Gregory Mathews in 1914, occurs in the western Indian Ocean and breeds on Aldabra Atoll. *F. a. trinitatis*, named by Brazilian zoologist Alípio de Miranda-Ribeiro in 1919, is found in the South Atlantic off Brazil and breeds on the Trindade Archipelago; it no longer nests on the main island, with fewer than 40 breeding pairs surviving on a small offshore islet. Some ornithologists question these subspecies, as they seem to differ only in size. Few museum specimens of the Atlantic *F. a. trinitatis* exist, making comparisons tough, but a 2017 study found differences in plumage color and skeleton, suggesting it should be treated as a separate species (*Fregata trinitatis*).
Measuring 66–81 cm (26–32 in) long with a wingspan of 155–193 cm (61–76 in) and a long, forked tail, the lesser frigatebird is the smallest frigatebird. Males weigh 625–875 g (1.378–1.929 lb), while heavier females weigh 760–955 g (1.676–2.105 lb). As with all frigatebirds, the male has a large red throat pouch inflated during courtship, which also involves calls, bill rattling, and wing spreading. The male is mostly black, with a white patch on the flank that exte
- Scientific name
- Fregata ariel
- Length
- 66–81 cm (26–32 in)
- Wingspan
- 155–193 cm (61–76 in)
- Male weight
- 625–875 g (1.378–1.929 lb)
- Female weight
- 760–955 g (1.676–2.105 lb)
- Conservation status
- Least concern (IUCN)
- Subspecies
- 3 (F. a. ariel, F. a. iredalei, F. a. trinitatis)
Lore & Background
Frigatebirds are built for flying; they rarely swim and cannot walk, but can climb trees and bushes. They have a very light skeleton and long, narrow wings. Their name probably derives from their habit of harassing other seabirds such as boobies and tropicbirds, forcing them to disgorge their catch, which is then caught before it hits the water. This kleptoparasitism seems more common among females but accounts for a small proportion of the diet, which mainly consists of squid and flying fish scooped from the sea surface. Breeding occurs between May and December in the Australian region, with one egg laid, taking 6–7 weeks to hatch. Fledglings remain in the nest for about six months and are cared for long after.
Reader's Guide
The lesser frigatebird is the most common and widespread frigatebird in Australian seas, with a total world population estimated at several hundred thousand birds. At least 6,000 pairs breed on the Aldabra Islands and another 15,000 pairs on islands off northern Australia, with the largest colonies on the Phoenix and Line Islands in the central Pacific. The species is classified by the IUCN as least concern due to its large population and extended range. However, the South Atlantic subspecies F. a. trinitatis has a tiny population, possibly fewer than 20 breeding pairs, restricted to a small rocky islet off Trindade Island. If recognized as a separate species, it would qualify as critically endangered. Conservation efforts, such as the elimination of feral cats from Howland, Baker, and Jarvis Islands, have led to the re-establishment and growth of colonies, demonstrating the species' vulnerability to introduced predators.
Did You Know?
- The lesser frigatebird is the smallest species of frigatebird, measuring 66–81 cm in length.
- Males have a large red gular sac that is inflated during courtship.
- The subspecies F. a. trinitatis in the South Atlantic may be a separate species, Fregata trinitatis, based on a 2017 study.
- Elimination of feral cats from Baker Island led to the return of nesting lesser frigatebirds, with about 16,200 individuals recorded in 2002.
More in Birds of the Indian Ocean 1-24
Spotted an error? Know more?
This is a living reference — every entry is fact-audited, and reader corrections feed straight into our audit queue. Suggest an edit · See this site's audit record