email a friend
printable version
Flores Hawk-eagle Nisaetus floris
BirdLife is updating this factsheet for the 2016 Red List
Please email us with any relevant information
BirdLife Species Champion Become a BirdLife Preventing Extinctions Programme Supporter
For information about BirdLife Species Champions and Species Guardians visit the BirdLife Preventing Extinctions Programme.

This species has an extremely small population that is undergoing a continuing and very rapid decline as a result of habitat clearance, and as a consequence it is listed as Critically Endangered.

Taxonomic source(s)
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
Gjershaug, J.O.; Kvalfy, K.; Rfv, N.; Prawiradilaga, D.M.; Suparman, U.; Rahman, Z. 2004. The taxonomic status of Flores Hawk Eagle Spizaetus floris. Forktail 20: 55-62.

Taxonomic note
Spizaetus cirrhatus (Sibley and Monroe 1990, 1993) has been split into S. cirrhatus and S. floris following Gjershaug et al. (2004). Spizaetus nanus, S. lanceolatus, S. philippensis, S. pinskeri, S. nipalensis, S. alboniger and S. bartelsi (Sibley and Monroe 1990, 1993) and S. cirrhatus and S. floris (Gjershaug et al. 2004) have been transferred into the genus Nisaetus following Haring et al. (2006). S. africanus and Hieraaetus fasciatus (Sibley and Monroe 1990, 1993) have both been transferred into Aquila, also following Haring et al. (2006); and H. kienerii (Sibley and Monroe 1990, 1993) has been transferred into the resurrected genus Lophotriorchis. The BirdLife Taxonomic Working Group is aware that phylogenetic analyses have been published which have proposed moving H. pennatus into Aquila but as not all published studies are concordant we prefer not to take a decision on this until cladogenesis of the 'booted eagles' has been resolved.

Distribution and population
Nisaetus floris is found in Indonesia, on the islands of Flores, Sumbawa and Lombok (on the borders of Rinjani National Park) as well as on two satellite islands, Satonda near Sumbawa and Rinca near Flores (Gjershaug et al. 2004). The species has also occurred on Komodo, with an individual photographed on a mangrove islet less than 800 m offshore in 2011 (Coates and Bishop 1997, Collaerts et al. 2013). It has recently been discovered on Alor and is apparently present throughout the island (Collaerts et al. 2013). A record from Paloe (Verheijen 1961) has not been confirmed. Its population size has been estimated at fewer than 100 pairs, based on the extent of suitable habitat and a territory size estimate of c. 40 km2 (Gjershaug et al. 2004), although it is estimated that at least 20 additional pairs inhabit Alor (Collaerts et al. 2013). The lack of records obtained during fieldwork within its range suggest it occurs at low densities, supporting this population estimate. Population trends are not known, but it is assumed to be declining owing to on-going forest loss in the Lesser Sundas.

Population justification
On the basis of distances between three neighbouring territories, the species's territory size was estimated at c. 40km2. Given that it is primarily dependent on forest, this implies that the total population size for the species is probably less than 100 pairs or 200 mature individuals. In addition at least 20 pairs have been estimated to occur on the island of Alor, representing another 40 mature individuals. It is estimated at 100-240 mature individuals, roughly equivalent to 150-360 individuals in total.

Trend justification
No empirical data are available, but deforestation and persecution are likely to be causing an on-going decline. Given the species's longevity scaled over the past three generations it has almost certainly experienced a very rapid decline.

It is found in lowland and submontane forest up to 1,600 m, with the majority of observations being made in lowland rainforest. It has been sighted over cultivated areas, but always close to intact or semi-intact forest; these records may relate to dispersing, immature or floater individuals rather than breeding adults. These records of birds outside core habitat suggest that the species may be able to disperse across the relatively narrow straits between islands so mixing between island sub-populations is inferred. Evidence suggests that breeding takes place during the dry season. Display flight and copulation have been observed on Flores in June-July. A territory size of 40 km2 per pair has been estimated (Gjershaug et al. 2004).

Habitat degradation and destruction are the most important threats; records are infrequent and it has rarely been recorded during trips to several large forest tracts suggesting extreme low density and casting some doubt on the assertion that it may be able to survive in a partly cultivated landscape. Protected areas in its range are currently too small to ensure its long-term survival. Persecution, due to its habit of preying on chickens, is another threat. In April 2014 an individual was shot in central Alor and the reason given was because the birds take chickens (Verbelen 2014). Capture for the cagebird trade is also a threat.

Conservation Actions Underway
CITES Appendix II. It has been recorded from Rinjani National Park on Lombok. Work is underway to inform local people of the importance of this species. Burung Indonesia are currently running a forest conservation project in western Flores where the species is found (M. Crosby in litt. 2014).

Conservation Actions Proposed
Ensure the survival of the species by securing further protected areas within its range. Reduce persecution and exploitation levels through local education programmes. Conduct further research on the species's population size, trends and range. Verify records from additional islands. Study movements and determine population structure.

Coates, B. J.; Bishop, K. D. 1997. A guide to the birds of Wallacea. Dove, Alderley, Australia.

Collaerts, P., Collaerts, E., Verbelen, P. and Trainor, C. 2013. Discovery of the Critically Endangered Flores Hawk Eagle Nisaetus flores on Alor Island, Indonesia. BirdingASIA 19: 48-51.

Gjershaug, J.O.; Kvalfy, K.; Rfv, N.; Prawiradilaga, D.M.; Suparman, U.; Rahman, Z. 2004. The taxonomic status of Flores Hawk Eagle Spizaetus floris. Forktail 20: 55-62.

IUCN. 2015. The IUCN Red List of Threatened Species. Version 2015-4. Available at: (Accessed: 19 November 2015).

Prawiradilaga, D.M.; Rfv, N.; Gjershaug, J.O.; Suparman, U.; Rahman, Z. (in prep). Territory size of the Flores Hawk Eagle Spizaetus floris on Flores, Indonesia.

Verbelen, P. 2014. Persecution and killing of Critically Endangered Flores Hawk Eagle Nisaetus floris on Alor, Lesser Sundas, Indonesia. BirdingASIA 21: 18.

Verheyen, J. A. J. 1961. Some notes on the birds of the islands of Paluë, Flores, observed from the 13th April to 5th May 1960. Ardea 49(3/4): 183-187.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Bird, J., Harding, M., Mahood, S., Taylor, J., Allinson, T, Martin, R & Ashpole, J

Butchart, S., Dutson, G., Eaton, J., Gjershaug, J., Collaerts, P., Prawiradilaga, D., Verbelen, F. & Crosby, M.

IUCN Red List evaluators
Symes, A.

Recommended citation
BirdLife International (2016) Species factsheet: Nisaetus floris. Downloaded from on 26/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 26/10/2016.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Flores hawk-eagle (Spizaetus floris) 0

Key facts
Current IUCN Red List category Critically Endangered
Family Accipitridae (Hawks, Eagles)
Species name author (E. Hartert, 1898)
Population size 100-240 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 10,000 km2
Country endemic? Yes
Links to further information
- Additional Information on this species