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Buceros bicornis 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Bucerotiformes Bucerotidae

Scientific Name: Buceros bicornis
Species Authority: Linnaeus, 1758
Common Name(s):
English Great Hornbill
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2017
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Bishop, K., Naniwadekar, R.N., Datta, A. & Lo, P.
Facilitator/Compiler(s): Benstead, P., Gilroy, J., Khwaja, N., Taylor, J., Martin, R
Justification:
Although this species has a large range, it occurs at low densities and is patchily distributed. It may have a moderately small population and is considered to be declining moderately rapidly to rapidly throughout its range. it is therefore listed as Near Threatened as approaches the thresholds for listing as threatened under criteria A2cd+3cd+4cd; C1.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Buceros bicornis has a wide distribution, occurring in China (rare resident in west and south-west Yunnan and south-east Tibet), India (locally fairly common, but declining), Nepal (local and uncommon, largely in protected areas), Bhutan (fairly common), Bangladesh (vagrant), Myanmar (scarce to locally common resident throughout), Thailand (widespread, generally scarce but locally common), Laos (formerly common; currently widespread but scarce and a major decline has occurred), Vietnam (rare and declining resident), Cambodia (rare), peninsular Malaysia (uncommon to more or less common) and on Sumatra, Indonesia (now rare). 
The bulk of the population is found in India, where it is restricted to the Himalayan foothills, hill forests in northeast India and, disjunctly, the wet evergreen forests of west India. In the north and northeast there continue to be records from Uttarakhand, Uttar Pradesh, West Bengal, Assam, Meghalaya, Arunachal Pradesh, Nagaland and Mizoram, while in the wet western forests it occurs in Maharashtra, Goa, Karantaka, Kerala and Tamil Nadu (R. Naniwadekar and A. Datta in litt. 2016). Most are found within protected areas, principally National Parks (Rajaji, Dudhwa, Gorumana, Nokrek, Balphakram and Intanki [Rahmani 2012, R. Naniwadekar and A. Datta in litt. 2016]), Wildlife Sanctuaries (Karterniaghat, Mahanada, Neora Valley, Chapramari, Dehing Patkai, Borail, Nongkhyllem, Ngengpui, Lengteng, Tokalo Eaglenest, Kamlang, Bhagwan Mahavir and Mookambika Wildlife Sanctuaries [Birand and Pawar, 2004, Rahmani 2012, R. Naniwadekar and A. Datta in litt. 2016]), Tiger Reserves (Buxa, Pakke, Namdapha, Manas, Nameri, Kaziranga, Dampha, Kali, Kudremukh, Parambikulam, Periyar, Kalakad Mundanthurai, and Indira Gandhi Tiger Reserves [Birand and Pawar, 2004, Mudappa and Raman 2009, Rahmani 2012, R. Naniwadekar and A. Datta in litt. 2016]), and Reserved Forests (R. Naniwadekar and A. Datta in litt. 2016). The species was not recorded in unclassed (i.e. unprotected) forests in a state-wide survey of Arunachal Pradesh, although a significant population does occur in Reserved Forests (Naniwadekar et al. 2015). An interview-based survey across Arunachal Pradesh indicated that the species had been lost from five out of 16 sites in recent decades, including from two protected areas (Naniwadekar et al. 2015). 
In Nepal, Great Hornbill is present in Royal Chitwan and Bardia National Parks, though at relatively low density. It is patchily common in Bhutan, with the Mangde Chhu valley, the Royal Manas and the southern part of the Jigme Singye Wangchuck National Park the stronghold of the species in the country and populations apparently stable (Spierenburg 2005). The Chinese population is restricted to the southwest of the country, with scattered reports in south Yunnan along the international borders (Philip Lo in litt. 2016) and it is common at lower elevations in Yingjiang, from where there are breeding records (Philip Lo in litt. 2016). In Myanmar it is poorly known, though there are recent records from Sagaing and Kachin states in the north and from Nat Ma Tung National Park in the west of the country (King et al. 2001, eBird 2017).  An assessment of all hornbills across Thailand found Great Hornbill to be one of the more habitat tolerant species, yet the area of occurrence for the species derived from a maximum entropy species distribution model (36,131 km2) is only approximately one third of the area of suitable habitat calculated as present in 1992 (Trisurat et al. 2013). The species has been extirpated from the Mae-Ping-Omkoi protected area complex in north Thailand (Pattanavibool et al. 2004). Away from the north it occurs in most protected-area complexes in the country and is present in particularly high densities in Khao Yai National Park (R. Naniwadekar and A. Datta in litt. 2016). In Laos the species still present in Nakai-Nam Theun National Biodiversity Conservation Area, but appears to have declined considerably since being historically described as common. It is now highly localised in Vietnam, with most recent records from Cat Tien National Park and Deo Nui San in the south, but also from Phong Nha-Ke Bang National Park in central Vietnam (eBird 2017). The Cambodian population is concentrated in southern Mondulkiri in the southeast and the Cardamom and Elephant Mountains in the southwest, with small numbers also present where patches of evergreen forest persist in the north of the country (Goes 2013). In Peninsular Malaysia it remains widespread and is present in several protected areas including Royal Belum and Taman Negara National Parks, Panti Wildlife Sanctuary, Fraser's Hill, Temengor Forest Reserve and common on the island of Langkawi (R. Naniwadekar and A. Datta in litt. 2016, eBird 2017). However, the loss of lowland forest throughout the country is considered to have greatly reduced the area of suitable habitat present, as on Sumatra where it is now highly localised and very infrequently seen following extensive destruction of lowland forests (K. D. Bishop in litt. 2012).Comparable population densities of around 4 individuals per square kilometre have been reported from protected areas in northeast India, the Western Ghats and Thailand (Naniwadekar and Datta 2013, Jornburom et al. 2013, R. Naniwadekar and A. Datta in litt. 2016), but densities outside of strictly protected areas (even if adjacent) are considerably lower and often well below 1 bird per square kilometer (Gale and Thongaree 2006, Mudappa and Raman 2009, Naniwadekar et al. 2015).
Countries occurrence:
Native:
Bhutan; Cambodia; China; India; Indonesia; Lao People's Democratic Republic; Malaysia; Myanmar; Nepal; Thailand; Viet Nam
Vagrant:
Bangladesh
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:10300000
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):2000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Consistent population densities within protected areas in west and northeast India and Thailand of between 1.3 and 4 individuals per km2 indicate that the population within these sites, given the approximate habitat that lies within a suitable elevation range, can be estimated on a precautionary basis at 23,000 - 71,000 individuals. This is placed in the band 20 - 49,999 individuals, roughly equating to 13,000 - 27,000 mature individuals.

Trend Justification:  A moderately rapid decline is suspected to be occurring, as a result of the degradation and clearance of forests throughout the species's range, as well as persecution by hunters and trappers.
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:13000-27000Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:This species frequents wet evergreen and mixed deciduous forests, ranging out into open deciduous areas to visit fruit trees and ascending slopes to at least 1,560 m in south India (Mudappa and Raman 2009) and up to 2,000 m in Thailand (Poonswad et al. 2013). The abundance of this species tends to be correlated with the density of large trees, required for nesting, and it is therefore most common in unlogged forest (Datta 1998). Known nest trees include Tetrameles nudiflora, Dipterocarpus gracilis, Dipterocarpus turbinata, Cleistocalyx nervosum, Shorea faguetiana, Hopea odorata, Neobalanocarpys heimii, Palaquiuum ellipticum, Mangifera indica, Bombax ceiba, Mesua ferrea and Syzygium gardneri (R. Naniwadekar and A. Datta in litt. 2016). It has also been reported to nest in the non-native tree Grevillea robusta (R. Naniwadekar and A. Datta in litt. 2016). Figs comprise a major part of the diet (Poonswad et al. 1994, Kannan and James 1999, Datta and Rawat 2003, Naniwadekar et al. 2015b) but the species also takes eggs, amphibians, reptiles, insects, mammals and small birds (Kemp and Boesman 2017). The breeding season begins in March in northeast India, and between December and January in other parts of the range; throughout, the nesting period lasts around four months (Poonswad et al. 2013). As the female is incarcerated and dependent on the male during this time, home range size is considerable smaller (0.7 - 7 km2 [Poonswad and Tsuji 1994, R. Naniwadekar and A. Datta in litt. 2016]) than during the non-breeding period when it has been recorded as 138 km2 in Thailand (Keartumsom et al. 2011) and c. 50 km2 in northeast India (R. Naniwadekar and A. Datta in litt. 2016). 

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):18.4
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade: A casque can fetch up to $90, and a single tail feather $15 in northeast India (R. Naniwadekar and A. Datta in litt. 2016).

Threats [top]

Major Threat(s): Logging is likely to have impacted on this species throughout its range, particularly as it shows a preference for forest areas with large trees that may be targeted by loggers. Forest clearance for agriculture is also likely to have contributed to declines, and it is unable to persist in areas where lowland forest has been reduced to small fragments (Chang et al. 2013). It is particularly susceptible to hunting pressure as it is large and visits predictable feeding sites (such as fruiting trees), and it is highly prized for its fat (R. Naniwadekar and A. Datta in litt. 2016). The casque and tail feathers are targeted in many locations across the range; both are used as adornments by local communities (R. Naniwadekar and A. Datta in litt. 2016). It is also probably impacted by the pet trade (Eames 2008), with chicks reported as being collected in south India and Thailand (R. Naniwadekar and A. Datta in litt. 2016).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
CITES Appendix I. The species is captively bred in zoos (Jensen 2008). It occurs in protected areas across its range. The ecology of the species has been studied since 1981 as part of long-running research at Khao Yai National Park in Thailand (Poonswad et al. 1987, 1995, 1998, 2005). Active management of nesting cavities has been used to augment breeding success in the wild (Poonswad et al. 2005). Hornbill Nest Adoption Programs have been implemented in Budo Sungai-Padi National Park in southern Thailand since 1994 (Pasuwan et al. 2011) and in forests adjoining Pakke Tiger Reserve in Arunachal Pradesh, northeast India since 2011 (Rane and Datta 2015). Urban donors are encouraged to 'adopt' wild hornbill nests and the funds raised are used to pay for nest guardians to monitor and protect the nest sites. An additional nest monitoring and protection program is underway in Kerala with the Kadar community and the forest department (Bachan et al. 2011). Artificial nest boxes have been installed with some success at sites in Thailand (Pasuwan et al. 2011) and southern India (James et al. 2011).

Conservation Actions Proposed
Monitor populations across its range to determine the magnitude of declines and rates of range contraction. Campaign for the protection of remaining extensive tracts of lowland forest throughout its range. Develop a programme to reduce hunting of the species through raising awareness of the status of the species within communities that target the species. Develop the existing captive breeding population to support future reintroduction and supplementation efforts.

Amended [top]

Amended reason: Updated the Conservation actions, Geographic range, Habitats and ecology and Threats information fields, and the global references accordingly.

Citation: BirdLife International. 2017. Buceros bicornis. (amended version published in 2016) The IUCN Red List of Threatened Species 2017: e.T22682453A111254552. . Downloaded on 23 June 2017.
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