Justification of Red List Category
This spectacular hornbill has been uplisted from Near Threatened to Critically Endangered owing to severe hunting pressure for its casque and as a result of habitat loss from logging and agricultural conversion. Hunting pressure is expected to increase and spread across the species's range given the value that is placed on the species's 'ivory' casque in illegal trade.
The population size of this species has not been quantified; it is considered locally common.
An extremely rapid and severe decline is predicted to occur in this species's population over the next three generations (59 years) as a result of intense hunting pressure and habitat loss. The species has apparently almost disappeared from habitats where it was previously abundant on Sumatra (J. Eaton in litt. 2015).
This species is confined to the Sundaic lowlands, where it is known from south Tenasserim, Myanmar, peninsular Thailand, Sabah, Sarawak and Peninsular Malaysia, Singapore, Kalimantan and Sumatra, Indonesia and Brunei (BirdLife International 2001). It is generally scarce, occurring at low densities even in optimal habitat, and is is the least commonly encountered of the forest hornbills in Peninsular Malaysia (D. L. Yong in litt. 2016).
It occurs in primary semi-evergreen and evergreen lowland forest, up to 1,500 m. In particular, it prefers rugged terrain, especially in foothills, and can persist locally in selectively logged forest. It feeds on fruits, especially figs, but also on small animals including squirrels, snakes and birds and even other hornbill species (Kemp and Boesman 2014, Utoyo et al. 2017). Little is known of breeding biology however it is known to nest in natural holes in large trees (Kemp and Boesman 2014). In Thailand it mainly uses trees in the Diptocarpaceae family, particularly Hopea spp. and Shorea spp. (Meijaard et al. 2005).
The species is heavily targeted by hunters and illegally traded. The species has a solid 'horn' or 'casque' on the upper side of its beak which is highly prized. China is the biggest consumer of the casques which are often carved for decorations or used in traditional medicine (Hughes 2015). It has been recorded in trade in Laos (EIA 2015). Large numbers of hunters have been observed in the forests of Sumatra searching for this species (J. Eaton in litt. 2015), and in June 2015 a group of around 30 hunters was broken up in northern Sumatra (Hughes 2015). Currently the trade in this species is centered on Indonesia, but will likely move to Malaysia once the supply of birds runs low in Indonesia (S. Mahood in litt. 2015). Between March 2012 and August 2014 1,117 heads/casques were seized in Indonesia during enforcement actions, and in the same period 1,053 heads/casques were confiscated in China (Beastall et al. 2016). The trade network is thought to be largely managed by organised crime meaning that trade pressure is likely to continue, eventually reaching every part of the species's range and it will be very difficult to control (N. Collar in litt. 2015). In West Kalimantan, it is thought that as many as 500 birds were being killed every month in 2013, resulting in an annual loss of 6,000 individuals (Y. Hadiprakarsa in litt. 2015, Hii 2015). There is no information to suggest that such levels of exploitation should be any different in other Indonesian provinces, indeed trade in hundreds of birds per month from Sumatra has been reported within the last year (N. Collar in litt. 2015).
Owing to the species's breeding cycle, hunting is likely to have a particularly severe impact. The species's breeding cycle involves the female being incarcerated for c. 160 days, while the male provisions the female and nestling in the nest. Although the female will break out of the nest should the male stop providing food, she is likely to be in heavy moult and her ability to survive will be seriously compromised. Thus the killing of the male could lead to the death of both the chick and the female (N. Collar in litt. 2015). In addition to hunting the species for its casque, it is also targeted for its feathers. Although this trade is small, it exerts an additional pressure which is also likely to contribute to population declines (N. Collar in litt. 2015).
An analysis of remote sensing data on forest loss has estimated that the total area of forest within the species's range has decreased from c. 643,000 km2 in 2000 to c. 565,000 km2 in 2012, a loss of c. 12% (Tracewski et al. in prep.). Assuming that the rate of forest loss is constant, this represents a loss of c.25% of forest habitat within the species's range across three generation lengths (26.1 years). The species is generally confined to lowland and lower-slope forest up to 750 m elevation, an area which is targeted for conversion to oil palm and logging for timber (N. Collar in litt. 2015). The species has specific nesting requirements, using the largest trees and apparently requiring trees with nest holes topped with a perch for the male to use while provisioning the female (N. Collar in litt. 2015). Logging is therefore likely to significantly reduce available nest sites. As a fig-specialist it is also likely to be strongly affected by loss of fig trees due to logging (Meijaard et al. 2005). 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).
Conservation and Research Actions Underway
CITES Appendix I. In Thailand, poachers have been encouraged to become hornbill observers and guides for tourists (Hii 2015).
Conservation and Research Actions Proposed
Urgently enforce legislation to prevent illegal hunting. Support livelihoods in forest communities so that the incentive to poach is minimised. Monitor populations across the species's range to determine the magnitude of declines and rates of range contraction. Monitor the impact of hunting pressure on populations. Campaign for the protection of remaining tracts of lowland forest throughout the range.
110-120 cm very large hornbill. Mostly dark brown and white with long central tail feathers. Distinctive high red casque, yellow at front. Male with bare red areas on neck, female with pale turquoise skin on head and neck (Kemp and Boesman 2014). Voice A long series of rather high-pitched pooh calls which suddenly shift to several bisyllabic “poohooh” calls, ending in a harsh, cackling laugh (Kemp and Boesman 2014).
Text account compilers
Wheatley, H., Ashpole, J, Taylor, J., Benstead, P., Westrip, J., Gilroy, J., Symes, A.
Yong, D., Collar, N., Mahood, S., Eaton, J., Meijaard, E., Wirth, R.
BirdLife International (2018) Species factsheet: Rhinoplax vigil. Downloaded from http://www.birdlife.org on 15/08/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 15/08/2018.