The Flores hawk-eagle (''Nisaetus floris'') is a large

raptor Raptor or RAPTOR may refer to: Animals The word "raptor" refers to several groups of bird-like dinosaurs which primarily capture and subdue/kill prey with their talons. * Raptor (bird) or bird of prey, a bird that primarily hunts and feeds on ...

in the family

Accipitridae The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-s ...

. It is an endemic species to the Lesser Sunda Islands in

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

.Verhoeye, J. & Holmes. D. A. (1998). ''The birds of the islands of Flores -- a review''. Kukila 10:3-59. A member of the genus ''

Nisaetus ''Nisaetus'' (Crested hawk-eagles group) is a genus of subfamily Aquilinae found mainly in tropical Asia. They were earlier placed within the genus ''Spizaetus'' but molecular studies show that the Old World representatives were closer to the ge ...

'', it was considered as a subspecies of and

conspecific Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organis ...

with the

changeable hawk-eagle The changeable hawk-eagle ''(Nisaetus cirrhatus)'' or crested hawk-eagle is a large bird of prey species of the family Accipitridae. More informal or antiquated English common names include the marsh hawk-eagle or Indian crested hawk-eagle.Ferguso ...

but genetic studies have evidenced it as a legitimate species.Gjershaug, J. O., Kvaløy, K., Røv, N., Prawiradilaga, D. M., Suparman, U., and Rahman, Z. (2004).
The taxonomic status of Flores Hawk-Eagle Spizaetus floris.
' Forktail 20: 55–62 A forest dwelling predator, this species is classified as Critically Endangered due to

habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

and persecution.Raharjaningtrah, W., and Z. Rahman. 2004. ''Study on the distribution, habitat and ecology of Flores Hawk-eagle Spizaetus cirrhatus floris in Lombok, Sumbawa, Flores, Komodo, and Rinca Islands, Nusa Tenggara, Indonesia''. Annual Report of Pro Natura Fund, 13:177-191.

Description

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.del Hoyo, J., N. Collar, J. S. Marks, and C.J. Sharpe (2020). ''Flores Hawk-Eagle (Nisaetus floris)'', version 1.0. In Birds of the World (J. del Hoyo, A. Elliott, J. Sargatal, D. A. Christie, and E. de Juana, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.Collaerts, P., Collaerts, E., Verbelen, P. and Trainor, C.R. (2013). ''Discovery of the Critically Endangered Flores Hawk Eagle Nisaetus floris on Alor island, Indonesia''. BirdingASIA. 19: 48–51. It has traditionally been treated as a subspecies of the

; 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 but may range from . Claims it may measure as little as are probably due to confusion with other hawk-eagle species. The reported total lengths put in contention with the

mountain hawk-eagle The mountain hawk-eagle (''Nisaetus nipalensis'') or Hodgson's hawk-eagle, is a large bird of prey native to Asia. The latter name is in reference to the naturalist, Brian Houghton Hodgson, who described the species after collecting one himself ...

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.Ferguson-Lees, J., & Christie, D. A. (2001). ''Raptors of the World''. Houghton Mifflin Harcourt. One paper estimated a body mass of around for the Flores hawk-eagle. The wing chord of the Flores hawk-eagle is .

Range and habitat

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

, the Flores hawk-eagle is distributed in forests of Flores,

Lombok Lombok is an island in West Nusa Tenggara province, Indonesia. It forms part of the chain of the Lesser Sunda Islands, with the Lombok Strait separating it from Bali to the west and the Alas Strait between it and Sumbawa to the east. It is ...

and

Sumbawa Sumbawa is an Indonesian island, located in the middle of the Lesser Sunda Islands chain, with Lombok to the west, Flores to the east, and Sumba further to the southeast. Along with Lombok, it forms the province of West Nusa Tenggara, but th ...

in the Lesser Sundas. It mainly occurs in lowlands, but has been recorded at altitudes as high as . The Flores hawk-eagle is known to be reliant on

tropical rainforest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equa ...

. Most frequently they are seen flying over the

canopy Canopy may refer to: Plants * Canopy (biology), aboveground portion of plant community or crop (including forests) * Canopy (grape), aboveground portion of grapes Religion and ceremonies * Baldachin or canopy of state, typically placed over an ...

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.Coates, B.J. & Bishop, K. D. (1997). ''A guide to the birds of Wallacea''. Dove Publications, Alderley, Queensland, Australia. The use of both lowland and somewhat montane forest may be dictated by the extent of remnant forest.Global Raptor Information Network. 2021. Species account: ''Flores Hawk-eagle Nisaetus floris''. Downloaded from http://www.globalraptors.org on 29 January 2021. Spizaetus cirratus

Ecology

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

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s, lizards,

snake Snakes are elongated, limbless, carnivorous reptiles of the suborder Serpentes . Like all other squamates, snakes are ectothermic, amniote vertebrates covered in overlapping scales. Many species of snakes have skulls with several more j ...

s 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 Rail or rails may refer to: Rail transport *Rail transport and related matters *Rail (rail transport) or railway lines, the running surface of a railway Arts and media Film * ''Rails'' (film), a 1929 Italian film by Mario Camerini * ''Rail'' ( ...

.Trainor, C.R., Verbelen, P. & Johnstone, R.E. (2012). ''The avifauna of Alor and Pantar, Lesser Sundas, Indonesia''. Forktail 28:77–92. Suspected predation by Flores hawk-eagles has been reported on

large flying fox The large flying fox (''Pteropus vampyrus'', formerly ''Pteropus giganteus''), also known as the greater flying fox, Malayan flying fox, Malaysian flying fox, large fruit bat, kalang, or kalong, is a southeast Asian species of megabat in the f ...

es. 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.Verheijen, J.A. (1964). ''Breeding season on the Island of Flores''. Ardea, 52:194-201. No further details, including clutch size, egg appearance, incubation, parental behaviour or fledging, are known of their breeding habits.

Status

Due to ongoing

within its small range, capture for the cage bird trade and persecution due to its habit of taking

chicken The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adu ...

s, the Flores hawk-eagle is evaluated as critically endangered on the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

of Threatened Species. It is probably the world's rarest eagle species.

Poaching Poaching has been defined as the illegal hunting or capturing of wild animals, usually associated with land use rights. Poaching was once performed by impoverished peasants for subsistence purposes and to supplement meager diets. It was set a ...

may be ongoing and trappers may even come from other islands to kill these birds. However, the Flores hawk-eagle was once considered in western Flores be a "totem" or "empo," i.e., a human ancestor, and was not persecuted or killed but habitat destruction may have been long negatively effecting the species. Educational efforts have been undertaken to try to ensure local people's coexistence with this predatory bird. It is estimated that less than 100 pairs remain, based on a per pair occupancy of about . A more specific estimate put the total at about 75 projected pairs, with 10 pairs on Lombok, 38 pairs on Sumbawa, and 27 pairs on Flores.

References

External links

BirdLife Species Factsheet
{{Taxonbar, from=Q1116302

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.Verhoeye, J. & Holmes. D. A. (1998). ''The birds of the islands of Flores -- a review'' ...

Birds of Flores Birds of Lombok Birds of the Lesser Sunda Islands Critically endangered fauna of Asia