Flores hawk-eagle

The Flores hawk-eagle (Nisaetus floris) is a large raptor in the family Accipitridae. It is an endemic species to the Lesser Sunda Islands in Indonesia. A member of the genus Nisaetus, it was considered as a subspecies of and conspecific with the changeable hawk-eagle but genetic studies have evidenced it as a legitimate species. A forest dwelling predator, this species is classified as endangered due to habitat loss and persecution.

Adults have dark brown upperparts, a brown tail with six bars, a white patch in the wings that is visible in flight, white underparts, and a white head with fine brownish streaks on the crown (many books erroneously illustrate adults with largely brown heads). Furthermore, they have sparse light dark markings about the thighs. The white patches at the upperside of the primaries are a species diagnostic. Furthermore, the tail has 6, not 4–5, bars. It has traditionally been treated as a subspecies of the changeable hawk-eagle; at least in part because of confusion over the true adult plumage of the Flores hawk-eagle, which resembles the juvenile of the changeable hawk-eagle. Unlike that species, adult and juvenile Flores hawk-eagles are quite similar. Unlike some changeable hawk-eagles and many other Nisaetus, Flores hawk-eagles lack a head crest.

What data is available shows Flores hawk-eagles are a fair bit larger than the changeable hawk-eagle. The total length is usually reported at 75 to 79 cm (30 to 31 in) but may range from 71 to 82 cm (28 to 32 in). Claims it may measure as little as 60 cm (24 in) are probably due to confusion with other hawk-eagle species. The reported total lengths put in contention with the mountain hawk-eagle as the largest of all Nisaetus but the mountain species appears to significantly larger winged and more heavily built than the Flores species, which has the gracile and long-tailed form like the changeable hawk-eagle. However, no published weights are known for the Flores hawk-eagle. One paper estimated a body mass of around 2 kg (4.4 lb) for the Flores hawk-eagle. The wing chord of the Flores hawk-eagle is 430 to 462 mm (16.9 to 18.2 in).