The remaining population of this species is extremely small and severely fragmented. A combination of extensive loss of low to mid-altitude forest and hunting have resulted in an extremely rapid population decline, although effective conservation measures on Panay offer hope that declines can be stopped. Nevertheless it remains listed as Critically Endangered.
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.
Rhabdotorrhinus waldeni (del Hoyo and Collar 2014) was previously placed in the genus Aceros.
Aceros waldeni (Sharpe, 1877)
Distribution and populationAceros waldeni
60-65 cm. Medium-sized, forest-dwelling hornbill. Male has rufous head, neck and upper breast. Rest of body plumage blackish with glossed green upperparts. Black tail, broad white central band which stains buff through preening. Red bill and large casque. Orange bare orbital and gular skin. Female similar though black head, white bare orbital and gular skin tinged with blue, and black underparts and smaller casque. Similar spp. Visayan Tarictic Penelopides panini much smaller, pale base to tail and male has whitish head. Voice Loud, deep, short, cackling trill regularly repeated.
is endemic to the Western Visayas in the Philippines
, where it is presumed to have occurred on three islands: Guimaras, Negros and Panay. It is now absent from Guimaras and survives only on Negros and Panay (Collar et al.
1999). By 2006, the population in the Central Panay Mountain Range (CPMR) had been found by PhilConserve (formerly PESCP) to contain 502 breeding pairs (E. Curio in litt
. 2007, 2008), with 1,018 active nest holes located in 2008 (Alabado et al
. 2009). There have been no breeding records since 1997 (one pair) in the north-west Panay Peninsula where, however, no systematic search has been conducted. Due to the small size of the remaining forest in the peninsula (c.5,000 ha) any breeding there may have been sporadic and it has since almost certainly been extirpated, despite pro-active anti-poaching and other forest wardening activities orchestrated by local support groups
(W. Oliver in litt
. 2007). Despite unconfirmed records from Balinsasayao Twin Lakes Natural Park and Calinawan Forest (P. Jakosalem in litt.
2012), the species may be functionally extinct on Negros (E. Curio in litt
. 2007, 2008, J. Gonzalez in litt.
2012). Population justification
There were 752 active nest holes in the Central Panayan Mountain Range in 2007 (E. Curio in litt.
2008). This represents 1,504 mature individuals, and so it is sensible to estimate the mature population to number between 1,000-2,499. This equates to 1,500-3,749 individuals in total, rounded here to 1,500-4,000 individuals.Trend justification
This species's population is presumed to have decreased extremely rapidly in line with habitat loss, degradation, and hunting within its range over the last three generations. Although conservation measures on Panay have successfully reduced nest poaching, habitat loss and degradation is continuing and declines may continue in the future.Ecology
It inhabits closed-canopy forests, also frequenting logged areas and occasionally isolated trees in clearings. It is probably adapted to lower or mid-elevation forest, with records from 400-1,200 m on Panay and 300-950 m on Negros. It is omnivorous, taking some animal matter to its nests (Kauth et al
and feeding in the canopy on figs and other fruits. It may make local nomadic movements in response to food availability. It nests in large trees. Threats
Chronic deforestation has led to its extinction on Guimaras and its extreme scarcity elsewhere. An estimated 4% of Negros and 8% of Panay remained forested in 1988, although this has reportedly since been reduced to c.3% and c.6%, respectively
(W. Oliver in litt
. 2007). Only 10% (c.110 km2
) of this is thought to be below 1,000 m. It heavily utilises (at least temporally) forest fruits and thus is adversely affected by deforestation. Hunting has reportedly had severe impacts in the past, with one estimate of up to a quarter of the (then estimated) population of north-west Panay shot in a single day in 1997, although the validity of this report is uncertain. Nest poaching, whether for sale of incumbent females and their dependant chicks for human consumption or into local bird trade, is the most serious threat. Poaching affected c.50% of broods before the implementation of a nest guarding scheme which now protects about two thirds of all broods in the Central Panay Mountain Range, but until the nest guarding scheme can be expanded the remaining third are still vulnerable (W. Oliver in litt
. 2007; E. Curio in litt
. 2007, 2008). Conservation Actions Underway
CITES Appendix II. Mt Talinis, designated for protection, is being managed as a geothermal reserve, and The Twin Lakes Balinsasayao Natural Park benefits from conservation funding. Other sites with recent records include Mt Kanla-on Natural Park (Negros) and Northern Negros Natural Park, which receives nominal protection. A nest-guarding scheme by PhilConserve led to a reduction of nest poaching by 95% on Panay (Hembra et al
. 2006), and that population can be stabilised at its current size if inroads into the forest by small-scale logging can be stopped (E. Curio in litt
. 2007, 2008). The fledging of nearly 500 broods of 1-3 young each in the Central Panay Mountain Range was the consequence of this nest-protection scheme (Hembra et al
. 2006) and the aim is to expand nest protection into more southerly parts of the CPMR (E. Curio in litt
. 2007, 2008). Confiscated hornbills have been rehabilitated and released by PESCP/PhilConserve (E. Curio in litt
. 2007, 2008). PhilinCon (formerly PhilConserve) in collaboration with CAPE continues to monitor these crucial nest-sites at CPMR through a community-based nest warden scheme, where nest-poaching has been halted. As of December 2010, a total of 15 Aceros waldeni
have been successfully bred at Mari-it Wildlife Conservation Park (Lastimoza 2010). Five of these captive-bred hornbills were transferred to two facilities on Negros Island. This brings a total of eight hornbills forming the captive population in Negros Island, representing the founder populations for eventual re-introduction (Justo et al.
2011). Massive awareness campaigns have been developed by various conservation NGOs, highlighting the plight of hornbills in the Negros-Panay faunal region. Livelihood incentives such as carabao (work animals) are being given to hunters to establish permanent agricultural plots instead of shifting cultivation. Seedlings of fruit trees, basic farm tools, rice seeds and informal training are given to hunters by the Mari-it Wildlife Conservation Park to encourage them to take up alternative livelihoods (L. L. Lastimoza in litt
. 2008).Conservation Actions Proposed
Funds should be allocated primarily to in-situ protection along the lines of PhilConserve's guarding scheme (E. Curio in litt
. 2007, 2008). Disseminate and act upon results from recent island-wide surveys on Panay and Negros and conduct further surveys, particularly on Panay, to identify important sites. Continue community awareness programmes to reduce hunting and illegal logging on both Panay and Negros. Work in partnership at government level to strengthen protected area legislation and improve the network in the long term, and support the development of captive breeding and reintroduction programmes.
Alabado, A.; Lestino, R.; Venus, J.; Ibabao, M.; Kuenzel, T.; Curio, E. 2009. PESCPâ€™s Protection Program from 2002 to 2008 for the last substantial sized Population of the Dulungan Hornbill (Aceros waldeni) â€“ Final Report for 2008. Pp. 39-40 in: PESCP Fifteenth Annual Report, 2009 (unpublished report).
Collar, N. J.; Butchart, S. H. M. 2013. Conservation breeding and avian diversity: chances and challenges. International Zoo Yearbook.
Collar, N. J.; Mallari, N. A. D.; Tabaranza, B. R. J. 1999. Threatened birds of the Philippines: the Haribon Foundation/BirdLife International Red Data Book. Bookmark, Makati City.
Curio, E. 2004. On ornamental maturation of two Philippine hornbill species with a note on physiological colour change. Journal of Ornithology 145(3): 227-237.
Hembra, S. S.; Tacud, B.; Geronimo, E.; Villanueva, J.; Jamangul, J.; Sanchez, E.; Bagac, N.; Curio, E. 2006. Saving Philippine hornbills on Panay Island, Philippines. Re-introduction News: 45-46.
Justo, J. M. G.; Ledesma, M. M.; Oliver, W. L. R. 2011. Negros Forests and Ecological Foundation, Inc.-Biodiversity Conservation Centre 2011 Bi-annual Report (unpublished report).
Kauth, M.; Engel, S.; Lastimoza, L. L.; Curio, E. 1998. Observations on the breeding biology of the Writhed-billed Hornbill (Aceros waldeni) in the Philippines. Journal fÃ¼r Ornithologie 139: 475-483.
Lastimoza, L. L. 2010. Mari-it Wildlife Conservation Park Third Quater Report for 2010 (unpublished report).
Further web sources of information
Detailed species accounts from the Threatened birds of Asia: the BirdLife International Red Data Book (BirdLife International 2001).
Explore HBW Alive for further information on this species
View photos and videos and hear sounds of this species from the Internet Bird Collection
Text account compilers
Benstead, P., Bird, J., Butchart, S., Davidson, P., Lowen, J., Peet, N., Symes, A., Taylor, J. & Allinson, T
Curio, E., Lastimoza, L., Oliver, W., Jakosalem, P. & Gonzalez, J.
BirdLife International (2015) Species factsheet: Rhabdotorrhinus waldeni. Downloaded from
http://www.birdlife.org on 29/03/2015.
Recommended citation for factsheets for more than one species: BirdLife International (2015) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 29/03/2015.
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
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