VU
Rhinoceros Hornbill Buceros rhinoceros



Justification

Justification of Red List Category
This species is largely restricted to extensive tracts of primary evergreen forest within a region experiencing high rates of deforestation. Even though the species is widespread within its range, high hunting pressure is exacerbating the population decline caused by habitat loss. The species is suspected to undergo a large population reduction over the next three generations. Therefore, it is listed as Vulnerable.

Population justification
The population size of this species has not been quantified. The species is widespread throughout its range, but occurs at low densities, even in suitable habitat (Poonswad et al. 2013).

Trend justification
An analysis of deforestation between 2000 and 2012 estimated forest loss within the species's range at a rate equivalent to 44% over three generation lengths (55 years) (Tracewski et al. 2016). Being largely restricted to primary forests and intolerant of habitat conversion, the species is additionally threatened by hunting. Thus, its actual rate of population decline is likely greater than the estimate decline based on forest loss alone, possibly exceeding 44% over three generations. The rate of decline is therefore placed in the band 44-49% over three generations. Since this species has a long generation length, with three generations stretching over 55 years, there is insufficient evidence to calculate the magnitude of reduction over the past three generations. Assuming the recent rate of decline remains constant, the species is projected to decline by 44-49% over the next three generations.

Distribution and population

Buceros rhinoceros is confined to the Sundaic lowlands of extreme south peninsular Thailand (where the only suitable habitat is in extensive primary forest in the Hala Bala area [Trisurat et al. 2013]), Sabah, Sarawak and Peninsular Malaysia, Kalimantan, Sumatra and Java, Indonesia and Brunei (BirdLife International 2001). It is locally extinct in Singapore.

Ecology

This species occurs in extensive areas of primary lowland and hill forest, extending into tall secondary forest and swamp forests, up to 1,400 m.When foraging, it crosses occasionally disturbed areas and plantations (Poonswad et al. 2013). It mainly feeds on fruits, but also takes small animals like arthropods, lizards, tree-frogs and bird eggs (Kemp and Boesman 2018). It breeds aseasonally, with nests being placed in natural tree cavities in 9-15m height (Kemp and Boesman 2018)

Threats

Forest destruction in the Sundaic lowlands of Indonesia has been extensive as a result of commercial and illegal logging, as well as agricultural development. An analysis of forest loss from 2000 to 2012 estimated forest loss within the species's range at 43.8% across three generation lengths (Tracewski et al. 2016). Additionally, the species is known to be impacted by hunting. It is caught for food, trade and the use of body parts in ceremonial dress (Kinnaird and O'Brien 2007, Kemp and Boesman 2018), especially on Borneo. The species may also be taken as ‘bycatch’ by hunters targeting Helmeted Hornbill Rhinoplax vigil (R. Wirth in litt. 2017). The rate of decline due to hunting is uncertain.

Conservation actions

Conservation Actions Underway
CITES Appendix II. Occurs in several protected areas, including Taman Negara National Park (Malaysia), Gunung Leuser and Way Kambas National Parks and Berbak Game Reserve (Sumatra) and Danum Valley Conservation Area (Borneo).

Conservation Actions Proposed
Monitor populations across the range to determine the magnitude of declines and rates of range contraction. Campaign for the protection of remaining extensive tracts of lowland forest in the Sundaic region. Restrict hunting.

Identification

c.90-100 cm. Very large black hornbill with black plumage, white thighs and vent and black band across the white tail; orange bill and prominent red horn-shaped casque with thick black line along the rear edge. Voice Gives a series of short, resonant rroh calls.

Acknowledgements

Text account compilers
Hermes, C., Gilroy, J., Martin, R., Benstead, P., Taylor, J., Westrip, J.

Contributors
Wirth, R.


Recommended citation
BirdLife International (2020) Species factsheet: Buceros rhinoceros. Downloaded from http://www.birdlife.org on 25/05/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 25/05/2020.