Flores Hawk-Eagle
Nisaetus floris
A large eagle with a bright white head and underside and a chocolate-brown back and uppertail. In flight, appears entirely white except for bold dark bars and tips on outer wings and tail. A rare eagle of forested lowlands and foothills, restricted to several of the Lesser Sundas islands. Larger than immature Rufous-bellied Eagle, with bolder tail bars, an all-white head, and noticeably bulging inner wings, unlike Rufous-bellied. Differs from Short-toed Snake-Eagle in its lack of dark markings on underside of forewing and its clean white underparts.
Identification
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.<p>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).
Taxonomy
- Scientific name
- Nisaetus floris
- Authority
- (Hartert, EJO, 1898)
- Order
- Accipitriformes
- Family
- Accipitridae
- Genus
- Nisaetus
Range and habitat
An Indonesian endemic, the Flores hawk-eagle is distributed in forests of Flores, Lombok and Sumbawa in the Lesser Sundas. It mainly occurs in lowlands, but has been recorded at altitudes as high as 1,600 metres (5,200 ft). The Flores hawk-eagle is known to be reliant on tropical rainforest. Most frequently they are seen flying over the canopy over slight slopes of the forest. They are sometimes reported as foraging over cultivations but this is only in areas adjacent to large stretches of forest. The use of both lowland and somewhat montane forest may be dictated by the extent of remnant forest.
- Migration
- Resident species
Behavior
Though clearly sedentary and non-migratory as are most tropical raptors, Flores hawk-eagles can disperse widely, mainly after their young disperse from their parent's range. Clearly, given their distribution across multiple islands, they are capable of crossing narrow straits. The call has been recorded as a loud, shrill and prolonged whistle. Next to nothing is known of the diet of Flores hawk-eagles. What is presumed is largely projected from related species, such as their presumed propensity for perch hunting. The presumed diet may consist of birds, lizards, snakes and mammals, but again this may be extrapolated from the diet of other hawk-eagles. Incidences of predation by this species on snakes have been observed and one Flores hawk-eagle was seen carrying what was thought to be a rail. Suspected predation by Flores hawk-eagles has been reported on large flying foxes. Nest activity by the species has been reported in March, April, May and August, with one downed tree reported by locals as containing a nest with a large eaglet in the latter month. Based on what little activity has been recorded, it appears that Flores hawk-eagle breeding season occurs during the dry season. No further details, including clutch size, egg appearance, incubation, parental behaviour or fledging, are known of their breeding habits.
Conservation
- Population trend
- declining
Photos
Distribution
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