Sulu Hornbill Anthracoceros montani


Justification of Red List Category
This hornbill faces the possibility of imminent extinction. It has a tiny population probably now confined to just one island. It is likely to be declining very rapidly owing to the continuing loss and degradation of the few remaining forest tracts in its range, and levels of exploitation. For these reasons, it is listed as Critically Endangered.

Population justification
The species perhaps numbers fewer than 20 pairs in the main mountain range of Tawi-Tawi. Therefore, the population size is considered to be extremely small, and is placed here in the range 1-49 mature individuals.

Trend justification
Described as common to abundant in the late 19th century, this species is thought to have undergone a very rapid decline over the last ten years, and persists with certainty only on Tawi-Tawi. Here, extremely rapid conversion of habitat to oil palm plantations was predicted to cause near-total forest loss, but to date these predictions have not been vindicated.

Distribution and population

This species is endemic to three islands in the Sulu archipelago in the Philippines, and may now be restricted to just one of these. Described as common to abundant in the late 19th century, it has undergone a drastic decline, and persists with certainty only on Tawi-Tawi. Evidence suggests that its population is extremely low, perhaps numbering fewer than 20 pairs in the main mountain range. During a visit in February and June 2009, four individuals were reported in contiguous areas over two days on Tawi-Tawi (I. Sarenas in litt. 2010). In 2014, 10 mature individuals were seen (Paguntalan et al. 2017), the largest sighting in recent years. A local villager reported a nest sighting (including a chick) in 2015, found on a fallen dipterocarp tree (Strange 2018). Surveys in 2018 found five individuals in the Panglima Sugala habitat of Tawi-Tawi, at an elevation of approximately 250 m (Strange 2018). An estimated 250-300 km2 of forest remained on Tawi-Tawi in 2001, although much of this included selectively logged forest (Mallari et al. 2001), and further declines have been noted since. The species is now likely to exist in a forest patch of c. 10 km2 (Strange 2018). Fortunately, the rate of clearance for oil palm plantations is lower than was feared previously. The species is thought to be extinct on Jolo (Sulu), but this requires confirmation. It is almost certainly extinct on Sanga-Sanga. Local reports from 1995 suggested that it may visit the small islands of Tandubatu, Dundangan and Baliungan, though these hold very little primary forest (D. Allen in litt. 2012) and are unlikely to sustain resident populations.


It inhabits primary dipterocarp forest, typically on mountain slopes (although this may simply reflect a constraint enforced by forest loss), occasionally visiting isolated fruiting trees over 1 km from the nearest forest. It requires large trees for nesting. Whilst the species's diet mainly consists of fruit, small lizards and some insects may also be consumed (Kemp et al. 2020). 


Jolo (Sulu) and Sanga-Sanga have apparently been almost completely deforested. By the mid-1990s, rapid clearance of primary forest on Tawi-Tawi had rendered remaining lowland patches highly degraded, although plans to replace these with oil-palm plantations seem to have stalled, while the rate of logging has slowed with the remainder of forest being confined to rugged mountainous areas. Conversion to rubber plantations and mining activities remain a threat to existing forest (D. Allen in litt. 2012, 2016). There have been examples of known sites being cleared for agriculture (I. Sarenas in litt. 2010). High gun ownership in the recent past may have resulted in it being shot for food and target practice. Young may continue to be harvested for food, and the species may be collected for trade. Hunting pressure on Tawi-Tawi may well have increased in recent years (I. Sarenas in litt. 2010).

Conservation actions

Conservation Actions Underway
CITES Appendix II. A Species Conservation Strategy and Action Plan was launched in 2019, targeting action towards species protection for the 2019-2029 period (Datta et al. 2019). Milestones to achieve include establishing security protocols, implementing surveys, engaging locals, investigating the threat of mining and implementing habitat enhancements (Datta et al. 2019).  Military activity and insurgency continue to present a serious obstacle to conservation work in the Sulus. There are no formal protected areas in the archipelago. A proposal exists to provide conservation funding for the Tawi-Tawi/Sulu Coastal Area, although neither the outcome nor the likely benefits to the species is known. However, community projects nevertheless persist, with a combined effort from the Municipal Council of Panglima Sugala, the Armed Forces of the Philippines, Philippine Marine Corps, and the Tausug tribe continuing to work on the 3,800 hectare area of Nug-as (L. Paguntalan in litt. 2020). Across logged areas, rehabilitation programmes also continue. Furthermore, throughout Tawi-Tawi, 26 communities are TAWSI (Tawi-Tawi Advocates for Widllife Support Initiative) Rangers, with ongoing funding provided by external sources for further conservation activities (L. Paguntalan in litt. 2020). A draft municipal resolution for the banning of hunting or capture of Tawi-Tawi endemics has been developed and was planned to be passed in July 2010 (I. Sarenas in litt. 2010). The municipality of the region has also employed six Tawsi rangers to survey the local population (Strange 2018). Further plans are considered in order to engage local villagers in planting fig trees and other suitable food sources, as well as planting trees that are appropriate for nesting (Strange 2018). 

Conservation Actions Proposed
Conduct surveys in all remaining forest patches in the Sulus to identify key sites. Urgently establish formal protected areas in the centre-west of Tawi-Tawi to conserve populations in the main mountain range. Clarify the proposal for conservation funding for the Tawi-Tawi/Sulu Coastal Area. Continue and expand environmental awareness programmes and establish captive-breeding populations for future supplementation/reintroduction. Collar and Butchart (2013) suggested that captive breeding should be considered.


c.70 cm. Blackish hornbill with wholly white tail. Black bill and casque, bare blackish skin around eye and small patches near bill-base. Glossy dark greenish upperparts. Iris cream-coloured in male and dark brown in female. Pale tip to casque-less bill in juvenile, and sometimes whitish-tipped primaries. Voice Series of loud cackling and shrieking calls.


Text account compilers
Patil, I., Fernando, E., Datta, A.

Allen, D., Benstead, P., Bird, J., Butchart, S., Derhé, M., Khwaja, N., Lowen, J., Paguntalan, L., Sarenas, I., Symes, A. & Westrip, J.R.S.

Recommended citation
BirdLife International (2022) Species factsheet: Anthracoceros montani. Downloaded from on 04/12/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from on 04/12/2022.