Justification of Red List Category
This species occurs in primary and tall secondary rainforest within a region experiencing high rates of deforestation. Although generally tolerant of secondary habitats, the scale of logging and habitat loss is likely to exacerbate its affect on the population. The species is therefore suspected to be undergoing a moderately rapid population reduction. Therefore, it is listed as Near Threatened.
The species is reported to be widespread, but occurring at low densities (del Hoyo et al. 2001). In Bukit Barisan Selatan National Park, Sumatra, densities were estimated to be c. 3.05 birds/km2 (Anggraini et al. 2000). In East Malaysia, in the Crocker Range Park and Tawau Hills Park, the density of the species was observed to be between 1.6 individuals/km2 and 26.39 individuals/km2 respectively (Lakim and Biun 2005). In Peninsular Malaysia, inside Sungai Tekam Forestry Concession (Pahang state), density was observed to be 0.4 groups/km2 in a primary forest and 1.0, 0.4, 0.3, 0.5 groups/km2 in 0-6 month, 1-2, 3-4, and 5-6-year-old logged forest respectively (Johns 1987). In Kuala Lompat (Krau Wildlife Reserve), density was observed as 0.4 individuals/km2 (Medway and Wells 1971). Due to the temporal and spatial variation of population density estimates therefore (Anngraini et al. 2000), the population size of this species has not been formally quantified. In prime habitat, it can be considered locally common (Poonswad et al. 2013).
The population is suspected to be in decline owing to ongoing habitat destruction (del Hoyo et al. 2001). An analysis of deforestation between 2000 and 2012 estimated forest loss within the species's range at 19.7%, rounded to 20% forest loss over three generations (21 years) (Tracewski et al. 2016). While the species's apparent tolerance of some habitat degradation might buffer the detrimental effects of deforestation to a certain degree, the scale of logging and deforestation is likely to pose an exacerbated affect in the future. Thus, the rate of decline is tentatively placed in the band 20-29% over three generations. Assuming the recent rate of decline remains constant, the species is also projected to decline by 20-29% over the next three generations.
The species occurs in the Sunda region. It ranges from the extreme south of Myanmar and southern Thailand (where it is locally vulnerable; V Chimchome and P. Poonswad in litt 2020), through Peninsular Malaysia to Borneo, Sumatra and Natuna Island (Indonesia) and Brunei Darussalam. In Peninsular Malaysia, the species is found in Sabah and Sarawak (mostly in the forest interior of the Heart of Borneo and conservation areas of forest plantations; David et al. 2017; Davies and Payne 1982; Smythies 1999; Tuen 2005; Kemp and Kemp 1974; Sheldon et al. 2001; Unggang et al. 2017; Styring et al. 2011), but absent from smaller states such as Melaka, Penang, and Federal Territories (Y. C. Aik in litt 2020). Its stronghold remains in large forest complexes (either single or several joined) and protected areas (Davison 1987, Davison 1995, Lim and Tan 2000, Wells 1999, Chong 1998, Chong 1993, Siti Hawa Yatim 1993, Siti Hawa Yatim et al. 1985, Ong et al. 2000, Choo and Teresa 2001, Norsham and Teresa 2001, Abdul Kadir Abu Hashim 2002, Wells 1999, Yeap and Perumal, in press, Wells 1990, Yong et al. 2011). They are not found on forested large and medium-sized islands on the west and east coast of Peninsular Malaysia. It still persists in smaller protected areas (<10,000 ha) of Western Sarawak such as Tanjung Datu National Park (Sim and Liam 2001, Nurul Ashikeen Ab Razak et al. 2015) and Samunsam Wildlife Sanctuary (McKenzie and Tuyah 2017). Most sites in the region are identified as Important Hornbill Landscapes (IHL) and Important Bird Areas (IBA), as well as being linked to the Central Forest Spine Masterplan for Peninsular Malaysia (Yeap and Peruma, in press).
The species occurs in lowland, evergreen primary rainforest and mature secondary forest, mainly at elevations around 750 m, but occasionally up to 1,800 m. It prefers dense foothill forests along rivers and streams, but is also resident in selectively logged forests and along edges of clearings (Kemp et al. 2018). It can also be found in hilly dipterocarp forests (Wells 1999, Smythies 1999), and can persist in peat swamp forests and freshwater swamp forests (Biun and Matsain Mohd Buang 2014, Nather Khan et al. 1991, MNS 1998). The species however avoids heavily disturbed areas (Kemp et al. 2020). Its main food sources are fruits, but also insects, lizards and frogs (Kemp et al. 2018). It lives in groups of up to 20 individuals (Poonswad et al. 2013). The species breeds cooperatively (as observed in Peninsular Malaysia and Sabah; Wells 1999, Madge 1969, Styring et al. 2002, Smythies 1999), with the whole group helping at the nest, and throughout the year, mainly during periods with high food abundance (Kemp et al. 2018). An estimated 1-4 chicks can be produced per pair (Wells 1999, MNS Hornbill Conservation Project [unpublished data], Yeap et al. 2016).
Forest destruction in the Sunda region has been extensive as a result of commercial and illegal logging, conversion to agriculture (particularly plantations) and increasing human population pressure. Even though the species can tolerate a moderate level of habitat degradation and selective logging, it is extirpated in intensively logged areas (Kemp et al. 2018). Its preferred lowland forest habitat is particularly impacted by deforestation, even within protected areas (Kemp et al. 2018). An analysis of forest loss from 2000 to 2012 estimated deforestation within the species's range at c. 20% over three generations (Tracewski et al. 2016). Although it was considered the species may also be taken as 'bycatch' by hunters targeting Helmeted Hornbill Rhinoplax vigil (R. Wirth in litt. 2017), this is unlikely to be true for this species (A. Datta in litt. 2020).
Conservation Actions Underway
CITES Appendix II. Occurs in several protected areas in Sumatra (Bukit Barisan Selatan National Park, Way Kambas National Park, Gunung Leuser National Park and Kerinci-Seblat National Park) and Thailand (Hala-Bala Wildlife Sanctuary and Budo Sungai Padi National Park). Across Thailand, some national parks however suffer from extensive human disturbance such as illegal logging, forest encroachment, collection and poaching, and civil unrest (Kemp et al. 2020). Nevertheless, the undertaking of long-term conservation persists in local communities, with locals encouraged to collect data and preserve the species (Poonswad et al. 2012). In Budo, artificial nests were used successfully by the birds near the edges of protected areas (V. Chimchome and P. Poonswad in litt 2020).
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 forest throughout the species's range.
c.70 cm. Medium-sized hornbill with dark brown plumage, grey-brown tail with broad black tip; bare bluish skin around the eyes and on the throat; male has a black bill with small black casque, while the female's bill is mostly yellow. Voice Groups audible over a large distance, high-pitched chorus of rising and gobbling calls.
Text account compilers
Datta, A., Fernando, E., Patil, I.
Aik, Y.C., Butchart, S., Chimchome, V., Ekstrom, J., Hermes, C., Kinnaird, M., O'Brien, T., Poonswad, P., Westrip, J.R.S. & Wirth, R.
BirdLife International (2021) Species factsheet: Anorrhinus galeritus. Downloaded from http://www.birdlife.org on 23/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/10/2021.