This species qualifies as Vulnerable because it has a small population and a small range which is severely fragmented, both of which are declining owing to rapid forest loss. However, it has been proposed that the population size is lower than suggested here and that it may undergo extremely rapid population declines in the future; hence a higher threat category may be warranted.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Rhyticeros everetti Collar and Andrew (1988), Rhyticeros everetti everetti Collar and Andrew (1988)
Distribution and population
70 cm. Medium-sized, dark, forest-dwelling hornbill. Male blackish apart from dark rufous crown and nape, paler and buffier on throat. Large yellowish bill with serrated casque and red patch at base. Plumage of female entirely black. Voice Harsh clucking notes, short erm-err and cackling kokokokoko.
This species is endemic to the island of Sumba, Nusa Tenggara, Indonesia
. Fieldwork since 1989 previously resulted in a tentative population estimate of 4,000 individuals (based on a density of 2.3 hornbills/km2
, and an estimated 1,732 km2
total forest-cover) (BirdLife International 2001)
. Recent research on the population size needs to be reconciled, as estimates have ranged from 1,650 mature individuals on the whole island (based on delayed maturation and its near absence from small forest patches) (T. O'Brien in litt.
, to 6,400 individuals solely in the Manupeu-Tanadaru National Park (D. Mulyawati in litt.
. Although some areas of habitat are well protected (D. Mulyawati in litt.
, the species is likely to be declining overall owing to continued forest loss outside of reserves (T. O'Brien in litt.
, and future declines may be extremely rapid (
Kinnaird and O'Brien 2007)
. Population justification
Recent population estimates are difficult to reconcile, ranging from 1,650 mature individuals on the whole of Sumba, to 6,400 individuals in the Manupeu-Tanadaru National Park alone (D. Mulyawati in litt.
2010, T. O'Brien in litt.
2010), although another estimate of fewer than 4,000 individuals in total has been given (Burung Indonesia in litt
. 2011). A population size of 2,500-9,999 mature individuals is retained here until the differences between these estimates are accounted for.Trend justification
Despite the adequate protection of an area of lowland forest in the Manupeu-Tanadaru National Park
(D. Mulyawati in litt.
2010), an overall population decline of 30-49% is estimated owing to the extensive and on-going loss and fragmentation of forest habitats outside of the reserve. Ecology
Despite frequenting a variety of forested habitats, it shows a strong association with low altitude semi-evergreen forest containing large trees with a dense canopy. It is rare or absent in patches <10 km2
, and may only use them if they are within ranging distance of larger fragments (Sitompul et al
. It has also been recorded up to at least 950 m, at forest edges and in isolated trees or groves in parkland far from closed forest, although its occurrence in parkland may be very infrequent. Nest-cavities tend to be situated within evergreen forest in the trunks of large deciduous trees, especially Tetrameles nudiflora
, a species that is important for other threatened species on the island (e.g. Sulphur-crested Cockatoo Cacatua sulphurea
) (BirdLife International 2001)
destruction and fragmentation stemming from small-scale logging, fuelwood collection and clearance for cultivation or pasture poses the main threat. These pressures are exacerbated by fire resulting from a dry climate and uncontrolled burning to encourage new growth for cattle. Since the 19th century, c.60% of forest has been lost. This hornbill's preference for lowland areas further compounds the threat of habitat loss, as do the reported minor impacts of trade and exploitation for food (BirdLife International 2001)
. Although one large area of lowland forest appears to be well protected in the Manupeu-Tanadaru National Park (D. Mulyawati in litt.
, forest loss is likely to be continuing outside of reserves (T. O'Brien in litt.
. Conservation actions underway
CITES Appendix II. Populations occur in the recently established Manupeu-Tanahdaru National Park (MTNP) and Laiwangi-Wanggameti National Park (LWNP) (1,350 km2
combined), which are now monitored by government-run management authorities set up in 2006. Burung Indonesia has been working intensively on the strengthening the national park management on Sumba since 2002/2003. The project included facilitating local communities and government to develop village conservation agreement and to agree on the demarcation of the MTNP, resulting a reduced external pressure on illegal logging, forest destruction, and better law enforcement (A. Dian in litt.
. Population surveys were carried out for the species in the MTNP in 2009 (D. Mulyawati in litt.
. The illegal wildlife trade has been monitored since 2004, and in four big cities in Sumba there have been no cases of the species being recorded in captivity (D. Mulyawati in litt.
. Conservation actions proposed
Conduct detailed research into the breeding and foraging ecology of the species. Conduct an accurate population survey across the entire island and implement a monitoring programme to establish population trends. Gazette strict nature reserves at Yawila, Puronumbu and Luku Melolo, a wildlife sanctuary at Lulundilo and a forest park at Tanjung Ngunju. Support initiatives to establish and manage further protected areas. Continue to work with local communities to prevent lowland forest clearing, hunting and trapping. Reconcile differences in population estimates.
BirdLife International. 2001. Threatened birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, U.K.
Sitompul, A. F.; Kinnaird, M. F.; O'Brien, T. G. 2004. Size matters: the effects of forest fragmentation and resource availability on the endemic Sumba Hornbill Aceros everetti. Bird Conservation International 14: S23-S37.
Kinnaird, M. F.; O'Brien, T. G. 2007. The ecology and conservation of Asian Hornbills: farmers of the forest. University of Chicago Press, Chicago, IL, USA.
Further web sources of information
Detailed species accounts from the Threatened birds of Asia: the BirdLife International Red Data Book (BirdLife International 2001).
View photos and videos, and hear sounds of this species from the Internet Bird Collection
Text account compilers
Benstead, P., Calvert, R., Davidson, P., Mahood, S., O'Brien, A., Taylor, J.
Dian, A., Gonzalez, J., Kinnaird, M., Mulyawati, D., O'Brien, T.
IUCN Red List evaluators
Butchart, S., Symes, A.
BirdLife International (2013) Species factsheet: Aceros everetti. Downloaded from
http://www.birdlife.org on 23/05/2013.
Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 23/05/2013.
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