Archived 2015 topics: Helmeted Hornbill (Rhinoplax vigil): Uplist to Vulnerable or Endangered?

Helmeted Hornbill (Rhinoplax vigil) (BirdLife species factsheet) is currently classified as Near Threatened as a result of a suspected moderate decline due to habitat loss and hunting pressure.
The species occurs in primary semi-evergreen and evergreen lowland forest, up to 1,500 m. It prefers rugged terrain, especially in foothills, and can persist locally in selectively logged forest. The 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 and occurs at low densities even in optimal habitat. The population size of this this species has not been quantified.
A forthcoming analysis of remote sensing data on forest loss (Tracewski et al. in prep) has estimated that the total area of forest within the range of R. vigil has declined from c.643,000km2 in 2000 to c.565,000km2 in 2012, representing a loss of c.12% of forest habitat available to this forest-dependent species. 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 known to be targeted by hunters for its feathers and for its solid ‘ivory’ casque, which is used to produce handicrafts and traded with China. Previously, it was thought that capture rates may be relatively low as a result of the species becoming shy over centuries of hunting. However, recent reports suggest that the species is currently being traded at a large scale. A report by the Environmental Investigation Agency (2015) revealed that hornbill casques are being traded in Laos and a 2013 study found that around 6,000 helmeted hornbills were traded in 2013 in West Kalimantan alone (Y. Hadiprakarsa in: Hii, 2015). Given the low population densities of this species, it is probable that hunting at this scale is contributing to strong population declines in at least parts of its range.
Proposed change and reasoning:

Given the rate of forest lost within the species’s range and the additional pressure caused by hunting, it is likely that the species has undergone a reduction of at least 30% and possibly more than 50% over a period of three generations (26.1 years), and that the population will continue to decline. It is therefore proposed that the species is uplisted to Vulnerable or Endangered under Criteria A2, A3 and A4.

Additional information and comments on this proposal are welcomed.

BirdLife International. 2001. Threatened birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, U.K.

Environmental Investigation Agency (EIA). 2015. Sin City – Illegal wildlife trade in Laos’ Golden Triangle Special Economic Zone. London, UK.

Hii, R. 2015. Helmeted hornbills on the verge of extinction. Huffington Post, 5th March 2015. Retrieved from  on 30th June 2015.

Tracewski,L., Butchart, S.H.M., Di Marco, M., Ficetola,G.F., Rondinini,C., Symes, A., Wheatley, H., Beresford, A.E. & Buchanan, G.M. in prep. Quantifying the impact of 21st century deforestation on the extinction risk of terrestrial vertebrates. Manuscript in preparation.


Discussion written by Hannah Wheatley, BirdLife International 2015.

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8 Responses to Archived 2015 topics: Helmeted Hornbill (Rhinoplax vigil): Uplist to Vulnerable or Endangered?

  1. James Eaton says:

    Given the huge numbers we are finding in trade of this species (details to follow), and the reports of huge numbers of hunters descending on the Sumatran forests in search of this I will assume Endangered at the very least for this species unfortunately. On recent visits to Sumatra I now rarely even hear this bird in areas that before I would hear many on a single day (Ulu Masen, Isi-Isi in Aceh, Kerinci Seblat National Park).
    At least in Peninsular Malaysia there are few hunting reports, but deforestation does not appear to be easing.

    A very worrying situation is appearing with this species….


  2. Andy Symes (BirdLife) says:

    Simon Mahood has provided the following comment:

    Globally it is proving impossible to adequately protect wild populations of species whose body parts reach extremely high prices in the wildlife trade (elephants, rhinos, pangolins). Helmeted Hornbill can now be added to that list of species, see here so it can be surmised that it is going to be extremely difficult to stop the poaching. Whilst the trade is now centered on Indonesia, patterns of exploitation of other very high value species indicate that it will switch to Malaysia when the supply from Indonesia dries up.

    Given the timescales involved it may therefore be of no consequence that it “can persist locally in selectively logged forest”, although I would caution that whilst adults may blog around for years waiting to die of old age (or be poached) in logged forest, they are unlikely to breed and therefore they make no contribution to the persistence of the species. I’m trying to find a decent reference, but from what I recall Helmeted Hornbill has extremely specific nest site requirements: it always nests in a hole created through the loss of a large branch from a massive tree. Clearly these conditions will be infrequently met in logged forest, where most large trees will have been removed and any suitable standing dead trees are unlikely to persist for long.

  3. Hannah Wheatley (BirdLife) says:

    Roland Wirth has provided the following comment:

    Although nobody seems to know population numbers for the species, considering that this species is generally thought to occur at low densities, even a very optimistic estimate can’t be much more than low tens of thousands (and probably much less). So removing hundreds of birds every month since at least 2013 (almost certainly more than 10.000 over the last two to three years) and considering the monetary value of ‘bird ivory’ in China, numbers of birds killed are likely to even increase. Unless the trade can’t be stopped a massive future decline and local extinction over increasingly large areas of otherwise suitable habitat is almost a certainty and a “critically endangered” listing seems appropriate.

  4. I don’t have data on collection levels on Borneo but we have recently quantified forest loss in Borneo and provide evidence that forest loss in protected areas remains high:

    Gaveau, D. L. A., et al. 2013. Reconciling forest conservation and logging in Indonesian Borneo. PLoS ONE 8:e69887, 69881-69811.
    Gaveau, D. L. A., et al. 2014. Four decades of forest persistence, loss and logging on Borneo. PLOS ONE 9:e101654.

    For what it is worth, I compiled this information in the Helmeted Hornbill section of our Life After Logging book.

    HELMETED HORNBILL Rhinoplax vigil
    Taxonomy This is a monotypic genus without subspecies.
    Global range Peninsular Thailand, Malaya, Sumatra and Borneo.
    Population status and densities on Borneo Densities: 1.8 km2/pair in logged forest, up to 0.9 km2/pair and 0.5 km2/pair in 6-year logged forest and small isolates in Sabah (Johns 1988); 0.12 km2/pair in primary foothill forest in Sarawak (Kemp & Kemp 1975); 7–8 km2/pair in East Kalimantan (Leighton 1986). Anggraini et al. (2000) reported densities of 1.9 birds/km2 in Bukit Barisan National Park, Sumatra.
    Occurrence on small SE Asian islands Not known from offshore islands (n = 0)
    Habitat Moist evergreen forest at up to 1,100 m, absent from coastal peatswamp forests (Smythies 1957). Most abundant among foothills in the tops of large trees.
    Feeding ecology According to Leighton (1986) diet consists of fruits (Ficus spp., Parkia speciosa, Urostigma spp.), and half of the time is spent foraging for animal foods, including squirrels and birds. Hadiprakarsa and Kinnaird (2001), however, found that this species fed almost exclusively on figs (98.6% of diet) and only a small proportion of animals (1.4%).
    Breeding ecology Little studied. No obvious seasonality, clutch size 1–2, but only one chick ever recorded with adults. Nest holes in isolated forest trees (van Marle and Voous 1988); in Thailand the majority of nest trees are in the family Diptocarpaceae, particularly Hopea spp. and Shorea spp., with dbh ranging from 105–216.6 cm Thiensongrusamee et al. 2001); female emerges some time before the chick. Bred during fruiting peak and not in the year thereafter (Leighton 1986); home range size 770 ha (Leighton 1982).
    Social organization Resident as territorial monogamous pairs, apart from nomadic groups of subadults (Leighton & Leighton 1983). Mostly singly or in pairs; small flocks of eight, comprised of juveniles, subadults and non-breeding adults move and forage steadily through the canopy (Leighton 1986).
    Habitat loss and degradation Extends into selectively logged but not secondary forests (Kemp 1995); it may be extinct-prone in smaller forest fragments (Lambert & Collar 2002), and is considered the most likely species to suffer from logging, as it is a fig specialist.
    Conservation status Protected by Indonesian law; CITES Appendix II. Subject to loss of prime habitat through shifting cultivation and deforestation, and being killed for carving and medicinal use of ivory. Tail feathers are valued for war helmets. Listed as Lower risk/near threatened in the Red Data Book of threatened birds of Asia (BirdLife International 2001) and by IUCN (2002).

  5. Andy Symes (BirdLife) says:

    Recommended categorisation to be put forward to IUCN

    Based on further information received, we have been able to change the preliminary proposal and revise the recommended classification on the 2015 Red List to Critically Endangered under criterion A3.

    The final categorisation will be published on the BirdLife website in late October and on the IUCN website in November, following further checking of information relevant to the assessment by BirdLife and IUCN.

  6. Andy Symes (BirdLife) says:

    Nigel Collar has written the following summary of his thoughts on the status of the species:

    Why the Helmeted Hornbill should be uplisted to Critically Endangered

    1. Degree of trapping pressure for ‘ivory’.―Yoki Hadiprakarsa has estimated, with very reasonable evidence, that in West Kalimantan as many as 500 birds were being killed every month (6,000 a year) in 2013. An analysis based on density estimates in the 1990s found that for the killing of HH for their feathers to be sustainable, only one bird can be hunted per 84.2 km² of forest per year. Forest cover in West Kalimantan is 91,788 km², but over half of this is production forest, unsuitable for the species; assuming—wholly improbably; the true figure is likely to be much less—that 45,000 km² of the forest estate remain suitable, the number of birds that could have been harvested sustainably in 2013 was the number of birds being harvested every month during that year. There is no reason to assume that hunting pressure was any less in any other Indonesian province, and a precautionary view would be simply to extrapolate this rate to all those provinces that hold the species; indeed, Bosco Chan wrote to me that a contact of his in the Chinese ivory trade has received hundreds of birds per month from Sumatra, for the last year or so. The fact that James Eaton now finds it hard to see or hear birds in areas he visits on tours is evidence that fully supports a catastrophic loss of numbers of the species.

    2. Nature of trapping pressure for ‘ivory’.―A review by TRAFFIC South-East Asia of web-reported hornbill ivory confiscations (now in the process of submission to Bird Conservation International) in the past five years makes it clear that the trade is (i) heavy (several thousand birds confiscated; and this is likely to be a fraction of the actual confiscations, and the actual confiscations are likely to be a small fraction of the actual number trafficked), and (ii) the largely or wholly managed by organised crime, involving other wildlife materials but also much other contraband (notably drugs). This criminal network is highly efficient and utterly ruthless, which means (a) that the trade pressure will continue to be driven by major forces beyond institutional control, (b) it will eventually reach every part of the species’s range (TRAFFIC have a report that in 2014 for the first time this century a market on the border between Myanmar and China had HH ivory for sale), and (c) it will be impossible to control by force on the ground. Simon Mahood has commented with authority on this pattern of exploitation across a species’s range. Moreover, just as poachers killed the last Javan Rhinoceros in Vietnam, so here the last HH will be persecuted if good money can be made by supplying it to the clandestine trade.

    3. Magnified impact of trapping based on biological evidence.―The HH breeding cycle involves the incarceration of the female for 160 days. Any time that a male is killed there is a very high chance (I make it 40%) he will be feeding an incarcerated female and her chick. The chick will perish, and productivity will thereby reduce greatly across the population, indicating a time in the next ten years or so when natural replacement will perhaps be insignificant. Moreover, although the female breaks out of the nest when a male stops providing food, she is likely to be in heavy moult and her ability to survive will therefore be seriously compromised (females normally complete the moult cycle in the security of the nest). Thus the killing of one male stands a good chance of causing the death of two other birds.

    4. Degree of pressure for feathers.―This is small, but it is not insignificant, hence the study in the 1990s to assess the offtake rate consistent with sustainable usage. Any bird killed by indigenous people will contribute to the rate of population decline.

    5. Degree of pressure on habitat.―Three key aspects are relevant here.
    a. The species is generally confined to lowland and lower-slope forest to an elevation of 750 m. These are areas which have suffered the greatest onslaught from outright conversion to oil-palm or else logging for timber. These pressures are what caused the species to be listed as NT, but new analysis of the evidence might well now show that on these factors alone the species would better be treated as Vulnerable.
    b. The species has specific nesting requirements, using the largest trees, which are of course the ones most targeted by loggers. Moreover, it appears to need large trees which have nest-holes topped with a perch on which the male can sit while provisioning the female. This kind of configuration must itself represent a limitation on nesting densities, and is wholly unlikely to exist in tracts of logged forest.
    c. Although HH eats many animals, its vegetable diet is exclusively figs. According to Frank Lambert (who asked for this to be checked; I have not had the time to do so, but perhaps this can be done) fig density apparently drops by 75% in logged vs unlogged forest, meaning that the abundance of HH in logged forest is likely to be equivalently lower.

    So if you take all these factors together—massive current exploitation, massive penetrating power of criminal gangs to every part of the range, massive incentives to locally recruited hunters to kill birds, multiplication effects of killing breeding males, desperately low levels of recruitment, some exploitation by indigenous people, and habitat loss that has reduced the range, nest-site abundance and food-supply—you surely get to the point where the A criterion for CR is triggered with ease, at least with the help of the precautionary principle.

    Nigel Collar
    23 September 2015

  7. Ding Li Yong says:

    Helmeted Hornbill has the lowest density among hornbills in many Sundaic lowland forest sites and appears to be less tolerant to logging/habitat degradation than other species. Based on more than 200 field trips to the Panti Forest Reserve, Peninsular Malaysia (logged lowland plains-level + primary hill dipterocarp forest), from 1997 – 2015, I have recorded in only on 20 trips or less (i.e. encounter rate 1000sqkm) (6o field days), and in the submontane forests at Fraser’s Hill (visits between 2001-2014), both sites in Peninsular Malaysia – where it is consistently the least frequently encountered species (less often heard than either Rhinoceros or Great Hornbill). Surveys in Way Canguk (Bukit Barisan Selatan) and Harapan Forests found it to be regularly encountered – but my impression is that the bird tends to be easily detected (given its far-reaching calls), and thus is likely to give the false impression that it is common when in fact densities are low.

  8. Simon Mahood says:

    Could not agree more with Nigel.

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