Lesser frigatebird

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.

Description

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.

Taxonomy

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.

Status

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.

Subspecies

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.