EN
Wrinkled Hornbill Rhabdotorrhinus corrugatus



Justification

Justification of Red List Category
This species is restricted to primary forests within a region experiencing high rates of deforestation. The area of forest within its range has undergone a rapid rate of decline over recent years, which is thought to be continuing. The species is also threatened by hunting. The species's population size is therefore suspected to undergo a large reduction over the next three generations and for this reason it is listed as Endangered.

Population justification
The population size of this species has not been quantified, but it has been described as always uncommon.

Trend justification
An analysis of forest loss from 2000-2012 estimated forest loss within the species's range at a rate equivalent to 62% across three generation lengths (57 years) (Tracewski et al. 2016). The rate of population decline is suspected to be greater than this because the species is intolerant of degraded or secondary habitat and is also threatened by hunting, and is placed in the band 50-79% across three generations. Since this species has a long generation length, with three generations stretching over 57 years, we have 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 50-79% over the next three generations.

Distribution and population

This species is confined to the Sundaic lowlands of peninsular Thailand (though only limited recent sightings in the country [Trisurat et al. 2013]), Sabah, Sarawak and Peninsular Malaysia, Singapore (formerly), Kalimantan and Sumatra (including the Batu Islands), Indonesia and Brunei (BirdLife International 2001). The population size has not been quantified, but it has been described as always uncommon, and quite rare in forest remnants in the southern Thai-Malay peninsula (D. L. Yong and J. Eaton in litt. 2018). There are few recent records from Peninsular Thailand (D. L. Yong in litt. 2018). An analysis of forest loss from 2000-2012 estimated forest loss within the species's range at a rate equivalent to 62% across three generation lengths (Tracewski et al. 2016). The rate of population decline is suspected to be greater than this because the species is intolerant of degraded or secondary habitat and is also threatened by hunting.

Ecology

This species occurs in primary evergreen and swamp forests up to 1,000 m. It can persist in selectively logged forest if primary forests are adjacent, but it does not occur in secondary forest.

Threats

Rates of forest loss in the Sundaic lowlands have been extremely rapid, owing partly to the escalation of illegal logging and land conversion, with deliberate targeting of all remaining stands of valuable timber including those inside protected areas. Forest fires have also had a damaging effect (particularly in 1997-1998). An analysis of forest loss from 2000-2012 estimated forest loss within the species's range at a rate equivalent to 62% across three generation lengths (Tracewski et al. 2016). This species shows strong avoidance of degraded or secondary forests and is reliant on lowland forest (D. L. Yong and S. Mahood in litt. 2018), which is particularly threatened by land conversion for large-scale plantations of oil palm and rubber, as well as clearance for small-scale agriculture. The species requires large trees in which to nest, so logging of large trees is a particular threat (S. Mahood in litt. 2018). The species is also threatened by hunting and may be taken as 'bycatch' by hunters targeting Helmeted Hornbill Rhinoplax vigil (D. L. Yong in litt. 2018).

Conservation actions

Conservation Actions Underway
CITES Appendix II.

Conservation Actions Proposed
Conduct repeated surveys across the species's range to determine the magnitude of declines and rates of range contraction. Campaign for the protection of remaining tracts of lowland forest throughout the species's range.

Acknowledgements

Text account compilers
Gilroy, J., Benstead, P., Westrip, J., Wheatley, H., Taylor, J.

Contributors
Yong, D., Eaton, J., Mahood, S.


Recommended citation
BirdLife International (2020) Species factsheet: Rhabdotorrhinus corrugatus. Downloaded from http://www.birdlife.org on 09/08/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 09/08/2020.