VU
Sulawesi Hornbill Rhabdotorrhinus exarhatus



Justification

Justification of Red List Category
This species has been uplisted to Vulnerable because it has a rapidly declining population owing to destruction of its forest habitat and hunting.

Population justification
The global population size has not been quantified, but the species is reported to be locally 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. A. Holmes in litt. 1999 and Kinnaird and O’Brien 2007]) and hunting for food and for keeping as pets (del Hoyo et al. 2001).

Distribution and population

This species is endemic to Sulawesi, Indonesia. Race R. e. exarhatus occurs in northern Sulawesi and Lembeh island; race R. e. sanfordi occurs in southern Sulawesi and the islands of Muna and Butung.

Ecology

The species occurs in lowland primary forest, occasionally tall secondary forest, usually below 650 m asl but sometimes up to 1,100 m asl. Family groups sometimes in more open habitats (del Hoyo et al. 2001). Diet consists mainly of fruit (85%), also some small animals, mainly invertebrates. Forages mostly through foliage below the canopy. 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 forest trees for breeding (del Hoyo et al. 2001, F. Lambert in litt. 2011), nesting in natural cavities or old woodpecker holes. Nests in some sites used by Knobbed Hornbill Aceros cassidix.

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. A. Holmes in litt. 1999 and Kinnaird and O’Brien 2007). The species's specialised breeding requirements (including a dependence on large trees) makes them particularly vulnerable to forest loss and degradation (e.g. Winarni and Jones 2012). Hunting, both for food and for keeping as pets, is also a serious threat (del Hoyo et al. 2001). MacKinnon and MacKinnon (1980) documented a dramatic crash in the population at Tangkoko in 1978-1979 which may have been driven by disease introduced by domestic poultry into wild populations (T. O’Brien and M. Kinnaird in litt. 2006).

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.

Acknowledgements

Text account compilers
Derhé, M., Symes, A., Westrip, J.

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


Recommended citation
BirdLife International (2019) Species factsheet: Rhabdotorrhinus exarhatus. Downloaded from http://www.birdlife.org on 11/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 11/11/2019.