Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Bucerotiformes Bucerotidae

Scientific Name: Rhyticeros cassidix
Species Authority: (Temminck, 1823)
Common Name(s):
English Knobbed Hornbill
Aceros cassidix (Temminck, 1823)
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. Lynx Edicions BirdLife International.
Taxonomic Notes: Rhyticeros cassidix (del Hoyo and Collar 2014) was previously placed in the genus Aceros.
Identification information:

Assessment Information [top]

Red List Category & Criteria: Vulnerable A4cd ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Symes, A. & Butchart, S.
Contributor(s): Lambert, F., Mulyawati, D., O'Brien, T. & Holmes, D.
Facilitator/Compiler(s): Butchart, S., Derhé, M., Ekstrom, J., Gilroy, J.
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.
Previously published Red List assessments:
2009 Least Concern (LC)
2008 Least Concern (LC)
2004 Least Concern (LC)
2000 Lower Risk/least concern (LR/lc)
1994 Lower Risk/least concern (LR/lc)
1988 Lower Risk/least concern (LR/lc)

Geographic Range [top]

Range Description: This species 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).

Countries occurrence:
Continuing decline in area of occupancy (AOO): Unknown
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 167000
Continuing decline in extent of occurrence (EOO): Unknown
Extreme 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): 1800
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: 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).
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: Unknown Continuing decline of mature individuals: Yes
Extreme fluctuations: No Population severely fragmented: No
Continuing decline in subpopulations: Unknown
Extreme fluctuations in subpopulations: No All individuals in one subpopulation: No

Habitat and Ecology [top]

Habitat and Ecology: The species inhabits evergreen forest up to 1,800 m asl, especially in lowalnds below 1,100 m asl, 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).
Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 19
Movement patterns: Not a Migrant

Threats [top]

Major Threat(s): 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 Actions [top]

Conservation Actions: 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.

Citation: BirdLife International. 2012. Rhyticeros cassidix. The IUCN Red List of Threatened Species 2012: e.T22682525A40577863. . Downloaded on 09 October 2015.
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