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Knobbed Hornbill Rhyticeros cassidix

Justification
This species has been uplisted to Vulnerable because it has a rapidly declining population owing to destruction of its forest habitat, hunting, gold mining and fires.

Taxonomic source(s)
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.

Taxonomic note
Rhyticeros cassidix (del Hoyo and Collar 2014) was previously placed in the genus Aceros.

Synonym(s)
Aceros cassidix (Temminck, 1823)

Identification

Distribution and population
Aceros cassidix is endemic to Sulawesi and offshore islands of Lembeh, Togian Islands, Muna and Butung, Indonesia. It is described as 'common' in at least parts of its range (del Hoyo et al. 2001). However, a recent analysis has suggested that this species may be declining at a rate approaching 40% over three generations based on recent and ongoing rates of habitat loss on Sulawesi (D. Holmes in litt. 1999, Kinnaird and O'Brien 2007]).

Population justification
The global population size has not been quantified, but the species is reported to be locally very common (del Hoyo et al. 2001).

Trend justification
The population is suspected to be declining rapidly owing to ongoing habitat destruction (16.9% forest loss per ten years during 1985-1997; 36.1% loss per ten years during 1997-2001 on Sulawesi [based on D. Holmes in litt. 1999 and Kinnaird and O'Brien 2007]) and hunting for food, gold mining and fires (del Hoyo et al. 2001).

Ecology
The species inhabits evergreen forest up to 1,800 m, especially in lowalnds below 1,100 m, where it extends into patches of secondary forest, woodland and plantations to forage. Feeds mainly on fruit, but also on animals, including insects, bird eggs and nestlings. It forages mainly in the canopy, even plucking off fruits in flight. Also digs in soft wood. Chases off other birds and primates at feeding sites. In Gorontalo, Sulawesi, the species has been observed foraging in primary and abandoned selectively logged forest, including those in fairly close proximity to human settlements (D. Mulyawati in litt. 2010). It requires large trees for breeding, nesting in natural holes 13-53 m up in tall forests trees (del Hoyo et al. 2001, F. Lambert in litt. 2011).

Threats
The species is threatened with habitat destruction, with forest on Sulawesi being lost at a rate of 16.9% per ten years during 1985-1997; and 36.1% per ten years during 1997-2001 (based on D. Holmes in litt. 1999 and Kinnaird and O’Brien 2007). The species's specialised breeding requirements (including dependence on large trees) makes them particularly vulnerable to forest loss and degradation. Hunting is a serious threat, as well as gold mining and fires (following exceptional fires in 1997, fieldwork showed a significant drop in breeding success and population recruitment in subsequent years) (del Hoyo et al. 2001)

Conservation measures underway
None is known

Conservation measures proposed
Conduct further surveys to clarify its distribution and status. Monitor trends in the population. Protect remaining extensive tracts of forest, extend existing protected areas where appropriate, and strictly control hunting in protected areas. Lobby for improved logging practices that leave patches of old growth or large trees. Design and implement hornbill conservation programmes aimed at reducing hunting levels.

References
del Hoyo, J.; Elliott, A.; Sargatal, J. 2001. Handbook of the Birds of the World, vol. 6: Mousebirds to Hornbills. Lynx Edicions, Barcelona, Spain.

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
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
Butchart, S., Derhé, M., Ekstrom, J., Gilroy, J.

Contributors
Lambert, F., Mulyawati, D., O'Brien, T., Holmes, D.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Rhyticeros cassidix. Downloaded from http://www.birdlife.org on 30/10/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 30/10/2014.

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

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.

Key facts
Current IUCN Red List category Vulnerable
Family Bucerotidae (Hornbills)
Species name author (Temminck, 1823)
Population size Unknown mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 167,000 km2
Country endemic? Yes
Links to further information
- Additional Information on this species