This gregarious hornbill has a small, rapidly declining population as a result of hunting and extensive deforestation. It therefore qualifies as Vulnerable.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.
Distribution and populationAceros subrificollis
Male 86.5-89.5 cm, female 76-84 cm. Largish hornbill with pale head, neck and tail and bulging yellow gular pouch. Warm brownish base to bill. Similar spp. Wreathed Hornbill A. undulatus has larger, longer, corrugated bill, less peaked casque with fewer dark ridges, and blackish streak on gular pouch. Voice Loud keh-kek-kehk. Higher-pitched, and more quacking than Wreathed Hornbill. Hints Scrutinise any large flocks of hornbills in Myanmar, Thailand or Malaysia.
occurs in south-east Myanmar
, west, south-west and extreme southern Thailand
, and northern Peninsular Malaysia
(BirdLife International 2001). All previous records from northern Myanmar, India and Sumatra were the result of misidentifications. Historically described as relatively common to very abundant in Myanmar, there have been no recent records and it appears to have undergone a rapid decline, at least in the Sittang valley. In 1993, the Thai population was estimated at <1,000 individuals, although the recent discovery of a single roost of 900 birds in the extreme south suggests that this figure should be revised upwards. Several thousand individuals attend one or two roost-sites in northern Malaysia and this area clearly supports a key population. The Malaysian Nature Society has been monitoring seasonal migration movements since 2004 and has logged a maximum count of 3,261 individuals at Belum Temengor IBA; although subsequent counts have been much lower (Yeap Chin Aik in litt
. 2012). In southern Myanmar, 150 individuals were recorded flying to roost within Lampi Island Marine Park (EcoSwiss in litt
. 2007). Population justification
A population estimate of 2,500-9,999 individuals has been derived from analyses of records and surveys by BirdLife International (2001). This equates to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals. At least 1,000 are known from Thailand as well as strong population centres in northern Peninsula Malaysia and southern Myanmar. Regular monitoring has been conducted at Pos Chiong/Kg Tebang in Temengor Forest Reserve, Peninsular Malaysia since 2004. Numbers fluctuate greatly from year to year, with the highest count on a single occasion of 3,261 on 14 September 2008 (Yeap and Ong 2011). Subsequent counts have been much lower (less than 1,000 individuals) (C. A Yeap in litt
. 2012). Despite counts in previous years of between 2,500-3,000 individuals, less than 100 birds were counted in Perak, Malaysia in 2009 (F. Lambert in litt
. 2009). A roosting flock of between 700-900 individuals has been recorded at Bang Lang National Park in Yala Province, Thailand (P. Poonswad in litt
. 2012).Trend justification
Hunting, trapping and deforestation are suspected to be causing rapid population declines.Ecology
It occurs in mixed deciduous, dry and humid evergreen forests, mainly in the lowlands, but also hills to c.1,000 m. It has a varied diet, mainly comprising fruit but also invertebrates and small vertebrates. It nests from January-June, in holes in tall, broadleaved trees. May undertake seasonal local migrations in response to seasonal fruiting patterns, however this needs more investigation (C. A.Yeap in litt.
Its size and flocking tendency render it especially vulnerable to hunting, which is a particular problem in Thailand and Myanmar. It is also threatened by rampant deforestation and forest degradation of the lowlands and foothills, a threat exacerbated by its requirement for large areas of forest and large trees for nesting. An additional, more minor threat is posed by the pet trade, and it shows some sensitivity to disturbance, apparently avoiding active logging operations (Yeap Chin Aik in litt
. 2007). Conservation Actions Underway
CITES Appendix I and II. It occurs in at least four protected areas in Thailand; Huai Kha Khaeng, Hala-Bala, Khlong Saeng and Mae Nam Phachi Wildlife Sanctuaries, and Khao Laem, Kaeng Krachan and Sri Phang-nga National Parks (Chew and Supari 2000, Hornbill Project Thailand in litt
. 2007). The Thailand Hornbill Project repair nest sites annually and carry out systematic monitoring at breeding sites (P. Poonswad in litt
. 2012). Belum Temengor IBA appears to be a main stronghold of the species; the Belum proportion is now a protected area called Royal Belum State park, while Temengor remains a logging concession (Yeap Chin Aik in litt
. 2007). Efforts are being made to protect forest in the upper Perak catchment of Malaysia and in the lowlands of Tenasserim (at Myinmoletkat Biosphere Reserve), Myanmar, two areas of crucial importance for this species. It also occurs within Lampi Island Marine Park in Tenasserim, Myanmar (EcoSwiss in litt
. 2007). Hornbill Project Thailand is in the process of collecting and analysing data to determine population densities for the species. Efforts are being made to establish links so that organisations in Thailand and Peninsular Malaysia work collaboratively. Conservation Actions Proposed
Conduct further surveys to determine its distribution, status, population size and specific habitat requirements. Satellite tracking should be used to study movement pattern. Genetic analysis is needed to determine the number of subpopulations. Establish further protected areas within its range in Myanmar and Malaysia. Consolidate or expand all protected areas supporting populations and enforce strict anti-hunting laws within them. Lobby for improved logging practices that leave patches of old growth or large trees. Promote public awareness and community-based conservation initiatives to reduce hornbill hunting.
BirdLife International. 2001. Threatened birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, U.K.
Chew, H. H.; Supari, S. 2000. Observations of plain-pouched hornbills Aceros subruficollis in Tasek Temngor, Peninsula Malaysia. Forktail 16: 65-67.
Yeap, C. A. and Ong, T. 2011. Conservation of hornbills in the northern forest landscape, with emphasis on the Belum-Temengor forest complex, Peninsular Malaysia. Final Report (July 2008 - December 2010). Malaysian Nature Society, Kuala Lumpur.
Further web sources of information
Detailed species accounts from the Threatened birds of Asia: the BirdLife International Red Data Book (BirdLife International 2001).
Text account compilers
Benstead, P., Bird, J., Davidson, P., Peet, N., Tobias, J. & Allinson, T
EcoSwiss, Round, P., Gonzalez, J., Poonswad, P., Lambert, F. & Yeap, C.
IUCN Red List evaluators
Butchart, S., Symes, A.
BirdLife International (2014) Species factsheet: Aceros subruficollis. Downloaded from
http://www.birdlife.org on 09/03/2014.
Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from
http://www.birdlife.org on 09/03/2014.
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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Additional resources for this species