4 thoughts on “Rufous-headed Hornbill (Rhabdotorrhinus waldeni)”
Whilst I understand the rate of population decrease is not within the CR standard requirements listed above I still believe the species should be considered CR. The population size is still on the lower end (5000 individuals may be over-estimated but also not incorporating breeding success or availability as a long lived species), severely limited habitat availability (especially long term viability regarding nesting sites), and its general Ex Situ and geographic limitations, all remain it as a candidate for CR. As the recommendation above cites, the population is still thought to be either stable to declining, and the threats are far from mitigated, in fact on the cusp of getting worse in the near future with unprotected forest landscapes prime for mining or other anthropogenic destruction.
Also regarding the map, the Negros island locations should be considered as either Extinct or Possibly Extinct, with the species not being confirmed in any Negros forests for more than a decade.
Range
This Rufous-headed Hornbill (RHH) still qualifies as Critically Endangered due to severe hunting pressure and severely fragmented forest in Western Visayas. The species is probably functionally extinct in Negros Island. Were PhilBio’s last records are in Balinsasayao Twin Lakes Natural Park (BTLNP) where 3 individuals seen and observed in 2007 (with Lisa Paguntalan, Prof. Luc Lens and Godfrey); 4 ( individuals were also observed in by the PhilBio-MSU IIT team in Northern Negros Natural Park (NNNP) in 2014 (observers are Andrew Reintar, Kim Doble, Freddie Lozada and Godfrey); and a heard call in Mt Kanla-on Natural Park (MKNP) particularly in Wasay Forest in the Municipality of Murcia in Negros Occidental in 2015. This is the last observation record for the RHH since the sightings. We conducted synchronized biodiversity monitoring in the three protected areas in Negros Island BTLNP, NNNP, and MKNP in 2018 and 2019 the species were not recorded in the three natural parks.
For Panay Island, the species was reported or probably extinct(?) or extirpated in Northwest Panay Peninsula Natural Park(?) and Sibalon Natural Park (?) but needs to be confirmed and conduct more population studies in these sites. The stronghold of the RHH is within the Central Panay Mountain Range, which comprises the four provinces, the province of Antique, Aklan, Capiz, and Iloilo of which Antique and Aklan has the larger forest cover. Our study in raptly estimated around 1,000–2,499 mature individuals with a total number of individuals at 1,500–4,000 (Reintar et, al. 2022) although we still have crude estimate since we are conducting the survey only within two sites of Antique, in Forest of Sebaste and Culasi. We also conducted a study in the forest of Capiz in the Municipality of Pilar Forest where we observed 2 individuals in a lowland forest. Haribon conducted a study within Pandan, Sebaste, Culasi, and Tibiao in 2014, recording some RHH populations. The most recent monitoring activity conducted particularly on the RHH is the Dulungan Count (Hornbill Count) a synchronized biodiversity monitoring system conducted within 10 municipalities of Antique where we counted at more than 60 individuals in 5 localities, particularly in Sebaste (11), San Remigio (4), Pandan (10), Culasi (1), and Barbaza (1). A total of 30 RHH was recorded.
There’s a need to conduct more surveys in Aklan where the Forest is continuous with Antique Forest, particularly in the forest of Madalag and Ibajay forests where we recorded several individuals regularly in different transects. There’s also a need to conduct some surveys in Mibacao, Malinao, and other forests within the Aklan River Watershed, in forests of Lambunao, Janiuay, and Maasin, for the Municipality of Iloilo for confirmation on the presence of the species
Habitat
The species occurs in lowland forests, particularly in primary forests (Reintar et, al. 2022). We only had a few records in the secondary forest. In our recent survey in 2024 in Sebaste Forest survey the species mostly observed in the primary forest however, we also observed the species in advanced secondary forest. In 2016 our other transect line was within the primary forest advanced secondary forest but in 2024 some portion of the advanced secondary forest was converted into a coconut plantation and there are additional clearings were also observed particularly on the gullies and near river banks. On the Hornbill Count, results from the species were mostly observed in the primary forest and few sightings in the secondary forest.
Threats
There are several threats identified for RHH, like loss of habitat particularly lowland forest within Negros and Panay. The species was also recorded in Guimaras but is currently extirpated in the island. The species was heavily targeted by hunters and local trade within the province of Akland and poaching of juveniles within the forests of Antique and Aklan. We observed poacher camps and traps for other threatened species. In Antique we observed the changes of forests in 2016 and 2024. Encroachment for agriculture was prominently observed in several sites like Sebaste, Culasi, and San Remigio Antique. As well as other sites within the Central Panay Mountain Range. The forest of Antique is also selected for the development of hydropower plants and wind farms. All these developments are within the forest primary and secondary forest which threats more on these species.
Population
For our study on RHH and Visayan Hornbill in CPMR (Reintar et, al. 2022), we estimated 1,000–2,499 mature individuals with the total number of individuals at 1,500–4,000 for Panay Island. Which is the stronghold of the species. In Negros Island although we have previous records, we need to conduct more surveys in all sites to confirm records. But still, the population of RHH undergo an extremely rapid decline over the next few years as a result of intense hunting pressures in its stronghold in Central Panay Mountain Range and high pressure in conversion of forest to agriculture and maybe across Panay Island Forest. The species might be disappeared in Negros Island but need to be confirmed. For these, the RHH current population trend is decreasing.
With Negros Island’s lowland forest estimates raptly 20,000 to 22,000 (Paguntalan et, al. 2021) but there are few remaining lowland forests and mostly secondary forests and advanced secondary forests. The remaining primary forest in Negros Island are mostly higher elevation forest from 1000 ASL up.
Conservation Action
The Central Panay Mountain Range was proposed as a protected area decades ago but it didn’t prosper. However, in 2023 after several years of discussion, the Regional Development Council of Western Visayas came out with a resolution requesting the Department of Environment and Natural Resources Region 6 to conduct a Protected Areas Suitability Assessment (PASA) and declare Central Panay Mountain range as protected area under the National Integrated Protected Areas System (RA 7586). In support to the PASA Philippines Biodiversity Conservation Foundation, Inc. (PhilBio) conducted several assessments in some selected forests to support the PASA. In 2024 the DENR is targeting to develop a draft bill for the declaration of CPMR as a protected area.
In Panay Island, several activities are also in line with the Province of Antique together with PhilBio and Haribon Foundation would like to continue the second Hornbill Count or Dulungan Count which we have at least 120 volunteers counting the hornbill and collecting habitat characteristic data in each transect sites. Haribon Foundation is targeting Aklan Forest r survey this year. Haribon Foundation, UNDP, and PhilBio is also planning to conduct and localize the Philippines Biodiversity Strategy and Action Plan (PBSAP) this year or next year in line with the Kunming Montreal Global Biodiversity Framework. The Regional Development Council also requested DENR to develop the regional biodiversity action plan in partnership with PhilBio however the plan needed to be localized as a province to gain support. The province of Antique and several municipalities are now organizing its local forest protection activities, particularly in the Province of Antique particularly the Municipality of Sebaste.
In Negros Island, the Balinsasayao Twin Lakes Natural Park and the newest ASEAN Heritage site continuously conduct synchronized biodiversity monitoring or hornbill count biannually led by BTLNP Protected Area Management Office in participation of different volunteers and protected area management board members. PhilBio in Partnership with DENR conducts training on biodiversity monitoring systems in Mt Kanla-on Natural Park and Northern Negros Natural Park within the year.
The DENR Provincial Environment and Natural Resources Office leads the conduct of the Protected Areas Suitability Assessment in partnership with the Environment and Natural Resources Division of the Province of Negros Oriental and PhilBio. A survey was also concluded led by PhilBio, Environment and Natural Resources Division of the Province of Negros Oriental, the Mindanao State University Iligan Institute of Technology, and different local government units, concluded the survey within the higher elevation primary forest and lowland secondary and mixed forest plantation within the Cuernos de Negros Mountain Range. This mountain range will be proposed as protected area within the province of Negros Oriental. The Provinces of Negros Oriental and Occidental respectively also strengthened forest protection activities by deputizing forest rangers in all local government units as well as providing the budget for forest rehabilitation in key important sites. The DENR is also conducting forest rehabilitation through its National Greening Program. Both provinces of Negros Occidental and Oriental are also updating the Negros Island Biodiversity Strategy and Action Plan in line with Kunming Montreal Global Biodiversity Framework.
The DENR Biodiversity Management Bureau together with PhilBio and Philippine Government CITES representative is proposing the two critically endangered hornbills under CITES 1.
Moving forward
The Rhabdotorrhinus waldeni still warrants the Critically Endangered A2cd criterion rather the proposed Endangered because of the imminent threats and the forest stronghold within the Central Panay Mountain Range is not a nationally protected area. The threats to the species are not just poaching or hunting but also the development of renewable energies within its important forest range in the province of Antique. So downlisting to endangered now is not the right time. There is no concrete study to support population estimates within its range to downlist the species as endangered. It is also important to collect robust and scientific data to have a more reliable population estimate. PhilBio and partners will continue to conduct monitoring and collect robust data to have a more realistic population estimate using distance software however, we have some current funding constraints. Estimates should be based on science and reliable data, not on feelings.
References
Negros Island Biodiversity Strategy and Action Plan (2018). DENR- BMB and Philippines Biodiversity Conservation Foundation Inc., Bacolod City.
Paguntalan, L.J., Reintar A.R., & Jakosalem, P.G.C. (2021). Population density of Visayan Tarictic Hornbill Penelopides panini on Negros Island, Philippines. Journal of Asian Ornithology 37 (2021): 93–98.
Reintar A.R., Paguntalan, L.J., Jakosalem, P.G.C., Quidet, A.C.D., Warguez, D.A., & Peñaranda, E. (2022). Habitat preference and population density of threatened Visayan hornbills Penelopides panini and Rhabdotorrhinus waldeni in the Philippines. Journal of Threatened Taxa. Vol. 14. No 3.
Regarding the range, we no longer find the species in NW Panay. PhilinCon and Bristol Zoo have been conducting bird surveys there for the past three years and there have been no detections.
Whilst I understand the rate of population decrease is not within the CR standard requirements listed above I still believe the species should be considered CR. The population size is still on the lower end (5000 individuals may be over-estimated but also not incorporating breeding success or availability as a long lived species), severely limited habitat availability (especially long term viability regarding nesting sites), and its general Ex Situ and geographic limitations, all remain it as a candidate for CR. As the recommendation above cites, the population is still thought to be either stable to declining, and the threats are far from mitigated, in fact on the cusp of getting worse in the near future with unprotected forest landscapes prime for mining or other anthropogenic destruction.
Also regarding the map, the Negros island locations should be considered as either Extinct or Possibly Extinct, with the species not being confirmed in any Negros forests for more than a decade.
Range
This Rufous-headed Hornbill (RHH) still qualifies as Critically Endangered due to severe hunting pressure and severely fragmented forest in Western Visayas. The species is probably functionally extinct in Negros Island. Were PhilBio’s last records are in Balinsasayao Twin Lakes Natural Park (BTLNP) where 3 individuals seen and observed in 2007 (with Lisa Paguntalan, Prof. Luc Lens and Godfrey); 4 ( individuals were also observed in by the PhilBio-MSU IIT team in Northern Negros Natural Park (NNNP) in 2014 (observers are Andrew Reintar, Kim Doble, Freddie Lozada and Godfrey); and a heard call in Mt Kanla-on Natural Park (MKNP) particularly in Wasay Forest in the Municipality of Murcia in Negros Occidental in 2015. This is the last observation record for the RHH since the sightings. We conducted synchronized biodiversity monitoring in the three protected areas in Negros Island BTLNP, NNNP, and MKNP in 2018 and 2019 the species were not recorded in the three natural parks.
For Panay Island, the species was reported or probably extinct(?) or extirpated in Northwest Panay Peninsula Natural Park(?) and Sibalon Natural Park (?) but needs to be confirmed and conduct more population studies in these sites. The stronghold of the RHH is within the Central Panay Mountain Range, which comprises the four provinces, the province of Antique, Aklan, Capiz, and Iloilo of which Antique and Aklan has the larger forest cover. Our study in raptly estimated around 1,000–2,499 mature individuals with a total number of individuals at 1,500–4,000 (Reintar et, al. 2022) although we still have crude estimate since we are conducting the survey only within two sites of Antique, in Forest of Sebaste and Culasi. We also conducted a study in the forest of Capiz in the Municipality of Pilar Forest where we observed 2 individuals in a lowland forest. Haribon conducted a study within Pandan, Sebaste, Culasi, and Tibiao in 2014, recording some RHH populations. The most recent monitoring activity conducted particularly on the RHH is the Dulungan Count (Hornbill Count) a synchronized biodiversity monitoring system conducted within 10 municipalities of Antique where we counted at more than 60 individuals in 5 localities, particularly in Sebaste (11), San Remigio (4), Pandan (10), Culasi (1), and Barbaza (1). A total of 30 RHH was recorded.
There’s a need to conduct more surveys in Aklan where the Forest is continuous with Antique Forest, particularly in the forest of Madalag and Ibajay forests where we recorded several individuals regularly in different transects. There’s also a need to conduct some surveys in Mibacao, Malinao, and other forests within the Aklan River Watershed, in forests of Lambunao, Janiuay, and Maasin, for the Municipality of Iloilo for confirmation on the presence of the species
Habitat
The species occurs in lowland forests, particularly in primary forests (Reintar et, al. 2022). We only had a few records in the secondary forest. In our recent survey in 2024 in Sebaste Forest survey the species mostly observed in the primary forest however, we also observed the species in advanced secondary forest. In 2016 our other transect line was within the primary forest advanced secondary forest but in 2024 some portion of the advanced secondary forest was converted into a coconut plantation and there are additional clearings were also observed particularly on the gullies and near river banks. On the Hornbill Count, results from the species were mostly observed in the primary forest and few sightings in the secondary forest.
Threats
There are several threats identified for RHH, like loss of habitat particularly lowland forest within Negros and Panay. The species was also recorded in Guimaras but is currently extirpated in the island. The species was heavily targeted by hunters and local trade within the province of Akland and poaching of juveniles within the forests of Antique and Aklan. We observed poacher camps and traps for other threatened species. In Antique we observed the changes of forests in 2016 and 2024. Encroachment for agriculture was prominently observed in several sites like Sebaste, Culasi, and San Remigio Antique. As well as other sites within the Central Panay Mountain Range. The forest of Antique is also selected for the development of hydropower plants and wind farms. All these developments are within the forest primary and secondary forest which threats more on these species.
Population
For our study on RHH and Visayan Hornbill in CPMR (Reintar et, al. 2022), we estimated 1,000–2,499 mature individuals with the total number of individuals at 1,500–4,000 for Panay Island. Which is the stronghold of the species. In Negros Island although we have previous records, we need to conduct more surveys in all sites to confirm records. But still, the population of RHH undergo an extremely rapid decline over the next few years as a result of intense hunting pressures in its stronghold in Central Panay Mountain Range and high pressure in conversion of forest to agriculture and maybe across Panay Island Forest. The species might be disappeared in Negros Island but need to be confirmed. For these, the RHH current population trend is decreasing.
With Negros Island’s lowland forest estimates raptly 20,000 to 22,000 (Paguntalan et, al. 2021) but there are few remaining lowland forests and mostly secondary forests and advanced secondary forests. The remaining primary forest in Negros Island are mostly higher elevation forest from 1000 ASL up.
Conservation Action
The Central Panay Mountain Range was proposed as a protected area decades ago but it didn’t prosper. However, in 2023 after several years of discussion, the Regional Development Council of Western Visayas came out with a resolution requesting the Department of Environment and Natural Resources Region 6 to conduct a Protected Areas Suitability Assessment (PASA) and declare Central Panay Mountain range as protected area under the National Integrated Protected Areas System (RA 7586). In support to the PASA Philippines Biodiversity Conservation Foundation, Inc. (PhilBio) conducted several assessments in some selected forests to support the PASA. In 2024 the DENR is targeting to develop a draft bill for the declaration of CPMR as a protected area.
In Panay Island, several activities are also in line with the Province of Antique together with PhilBio and Haribon Foundation would like to continue the second Hornbill Count or Dulungan Count which we have at least 120 volunteers counting the hornbill and collecting habitat characteristic data in each transect sites. Haribon Foundation is targeting Aklan Forest r survey this year. Haribon Foundation, UNDP, and PhilBio is also planning to conduct and localize the Philippines Biodiversity Strategy and Action Plan (PBSAP) this year or next year in line with the Kunming Montreal Global Biodiversity Framework. The Regional Development Council also requested DENR to develop the regional biodiversity action plan in partnership with PhilBio however the plan needed to be localized as a province to gain support. The province of Antique and several municipalities are now organizing its local forest protection activities, particularly in the Province of Antique particularly the Municipality of Sebaste.
In Negros Island, the Balinsasayao Twin Lakes Natural Park and the newest ASEAN Heritage site continuously conduct synchronized biodiversity monitoring or hornbill count biannually led by BTLNP Protected Area Management Office in participation of different volunteers and protected area management board members. PhilBio in Partnership with DENR conducts training on biodiversity monitoring systems in Mt Kanla-on Natural Park and Northern Negros Natural Park within the year.
The DENR Provincial Environment and Natural Resources Office leads the conduct of the Protected Areas Suitability Assessment in partnership with the Environment and Natural Resources Division of the Province of Negros Oriental and PhilBio. A survey was also concluded led by PhilBio, Environment and Natural Resources Division of the Province of Negros Oriental, the Mindanao State University Iligan Institute of Technology, and different local government units, concluded the survey within the higher elevation primary forest and lowland secondary and mixed forest plantation within the Cuernos de Negros Mountain Range. This mountain range will be proposed as protected area within the province of Negros Oriental. The Provinces of Negros Oriental and Occidental respectively also strengthened forest protection activities by deputizing forest rangers in all local government units as well as providing the budget for forest rehabilitation in key important sites. The DENR is also conducting forest rehabilitation through its National Greening Program. Both provinces of Negros Occidental and Oriental are also updating the Negros Island Biodiversity Strategy and Action Plan in line with Kunming Montreal Global Biodiversity Framework.
The DENR Biodiversity Management Bureau together with PhilBio and Philippine Government CITES representative is proposing the two critically endangered hornbills under CITES 1.
Moving forward
The Rhabdotorrhinus waldeni still warrants the Critically Endangered A2cd criterion rather the proposed Endangered because of the imminent threats and the forest stronghold within the Central Panay Mountain Range is not a nationally protected area. The threats to the species are not just poaching or hunting but also the development of renewable energies within its important forest range in the province of Antique. So downlisting to endangered now is not the right time. There is no concrete study to support population estimates within its range to downlist the species as endangered. It is also important to collect robust and scientific data to have a more reliable population estimate. PhilBio and partners will continue to conduct monitoring and collect robust data to have a more realistic population estimate using distance software however, we have some current funding constraints. Estimates should be based on science and reliable data, not on feelings.
References
Negros Island Biodiversity Strategy and Action Plan (2018). DENR- BMB and Philippines Biodiversity Conservation Foundation Inc., Bacolod City.
Paguntalan, L.J., Reintar A.R., & Jakosalem, P.G.C. (2021). Population density of Visayan Tarictic Hornbill Penelopides panini on Negros Island, Philippines. Journal of Asian Ornithology 37 (2021): 93–98.
Reintar A.R., Paguntalan, L.J., Jakosalem, P.G.C., Quidet, A.C.D., Warguez, D.A., & Peñaranda, E. (2022). Habitat preference and population density of threatened Visayan hornbills Penelopides panini and Rhabdotorrhinus waldeni in the Philippines. Journal of Threatened Taxa. Vol. 14. No 3.
Regarding the range, we no longer find the species in NW Panay. PhilinCon and Bristol Zoo have been conducting bird surveys there for the past three years and there have been no detections.