Aldabra fody

The Aldabra fody (Foudia aldabrana) is a passerine bird in the family Ploceidae. It is endemic to Aldabra, an atoll northwest of Madagascar, part of Seychelles. Regarded as conspecific with the Comoros fody in the past, it is now recognized as a distinct species by the International Union for the Conservation of Nature (IUCN). Both sexes are yellow in color across much of the body, with breeding males orange-scarlet on the head and neck. The species has a large and powerful bill, used to compete with other birds of Aldabra for food. Nesting occurs over several months, often in introduced coconut palms and Casuarina trees. The Aldabra fody is considered endangered by the IUCN, threatened by predation of nests and drought. Hybridization with the related Madagascar fody has occurred in the past, but is not currently considered a danger to the species.

The Aldabra fody's bill is markedly long and heavy, a distinctive characteristic. The female is similar to a sparrow, but more yellow, with dark streaks and a more powerful bill. The breeding plumage of the male is orange-scarlet on the head and breast, with yellow on the back and body, sides and flanks imbued with olive-gray, a sulfur-yellow belly, yellowish white tips on the median covert feathers, and an orange rump. An article published in the Bulletin of the African Bird Club, a conservationist journal, described the males of the species as the "most attractive of all fodies". Immature birds are similar to the female. All plumages contain yellow tones, and all are more yellow than the related Comoros and Madagascar fodies, especially on the underparts.

There were no published recordings of the Aldabra fody's vocalizations as of 2013, but they have been well-described. There are a great variety, with many based on high-pitched and metallic two-eet, twee, or tee calls. They produce a trilling song sequence consisting of a variety of notes, described by one study as tsee-oo tsee-oo tsee-oo fsssssss looklooklooklooklook. Males generate a nasal "fizzing" noise associated with territorial defense, suggested by one ornithological encyclopedia to correspond to the fsssssss noise reported in the study. Birds advertise their territory with clear and loud tweet tweet two-eet, or simply tweet or two-eet notes. They may also produce three rapid, lower notes followed by two or three higher notes with more deliberation: teetiti twee twee. Males and females have different alarm sounds, with males trilling excitedly while females scold loudly and continuously (tic-tic tzip tic tzip tzip tic-tic). Females give a zeep zeep when soliciting copulation, with a psep pseep after mating.