Philippine Journal of Science 150 (S1): 347-362, Special Issue on Biodiversity ISSN 0031 - 7683 Date Received: 28 Sep 2020

Bird Observations in the Busa Mountain Range, Province,

Tristan Luap P. Senarillos1*, Kier Mitchel E. Pitogo2, and Jayson C. Ibañez1

1Philippine Eagle Foundation Inc, Center Malagos, Baguio District, City 8000 Philippines 2Department of Environment and Natural Resources Provincial Environment and Natural Resources Office South Block 1, Martinez Subdivision, City 9506 Philippines

The Busa Mountain Range hosts one of the last remaining forests in southern , Philippines. Previous surveys were confined only to the northern slope, leaving the southern slope in Sarangani Province a relatively understudied area in terms of avian fauna. To augment this gap, we did a rapid inventory survey of bird presence in the Busa Mountain Range employing a combination of line transects, point counts, opportunistic listing, and observation from vantage points, which were supplemented by secondary data from a previous avifaunal assessment. We recorded a total of 116 bird from 45 families and 88 genera. Despite the significant number in species tally, our survey of in the Busa Mountain Range is still inadequate because of the few field sites visited (10 localities) and limited survey time for each locality (82.85 person-hr on average). The presence of several threatened species (DAO 2019- 09: 16.37%, n= 19; IUCN V3.1: 13.79%, n= 16), endemic species (53.44%), and anthropogenic disturbance indicate the strong need for protection of the bird fauna and their habitats in the Busa Mountain Range.

Keywords: bird conservation, bird diversity, Mount Busa, Philippine eagle critical habitat, rapid survey, species checklist

INTRODUCTION conversion for agriculture and settlements, the remaining forest block in southern Mindanao is mostly confined The Busa Mountain Range is a key biodiversity area (KBA to these mountains (Namocatcat et al. 2015; DENR 116) and an extremely high conservation priority site in 2020). Recently, the mountain massif was declared as a the Philippines (Ong et al. 2002). It was also identified as local conservation area (LCA) by virtue of Resolution an important bird area for holding a significant number of No. 2020-10-042 passed by the Provincial Council of globally threatened and restricted-range species (Criteria Sarangani on 10 Mar 2020 as a step towards establishing A1 and Criteria A2, respectively; BirdLife International a long-term legal framework for the protection of the 2020a). The KBA 116 comprises the coastal range of the mountain range (Peralta 2020). mountains in Sarangani and Provinces that include the Mounts Busa, Three Kings (Talili), and The shared forests of Sarangani and South Cotabato Parker (Melibengoy). With the pressures brought by forest Provinces are a mix of secondary-growth, primary lowland evergreen, and lower and upper (mossy) *Corresponding Author: [email protected] montane forests that serve as critical watershed areas for

347 Philippine Journal of Science Senarillos et al.: Birds of Busa Mountain Vol. 150 No. S1, Special Issue on Biodiversity Range, Sarangani, Philippines the low-lying communities and habitats for threatened Site 2: Sitio Angko, Brgy. Batian, (6.155528° and restricted-range species of birds and other wildlife 124.491590°; 495 masl). This area is characterized by a (BirdLife International 2020a; Namocatcat et al. 2015; mix of shrubland, grassland, and agricultural areas. Forest DENR 2020). In the previous ornithological surveys and in the area was cleared to established settlements and collecting expeditions, assessments were only limited “kaingin” (slash-and-burn) farms. The abandoned kaingin to the Lake Sebu side of the mountain range (Dickinson farms were colonized by the highly invasive “buyo-buyo” et al. 1991; Robson and Davidson 1996; Kennedy et al. (Piper adduncum). 2000), making the remaining areas – particularly the southern slope in Sarangani – one of the least explored bird Site 3: Tambusong, Brgy. Batian, Maitum (6.168910° habitats in the Philippines. For this reason, the knowledge 124.499500°; 384 masl). This site is an open area located regarding bird species diversity in the Busa Mountain on a ridge top bounded on both sides by steep ravines and Range remains fragmented and minimal. has a good vantage view of the adjacent natural forest. It is composed primarily of cultivated areas for corn, upland To address current gaps, the Philippine Eagle Foundation rice, , and scrubland, which is also used by local (PEF) together with the Department of Environment and communities for grazing their livestock. While patches Natural Resources Region 12 (DENR RXII) listed bird of riparian forest habitat are present on the lower slope species found within the Philippine Eagle survey sites in of the ridge that is dominated by a mixture of primary the Busa Mountain Range. This initial attempt generated forest trees. the first comprehensive list of birds occurring in the mountain range and provided preliminary information on Site 4: Sankil, Brgy, Batian, Maitum (6.166390° bird species that are regarded as globally important due to 124.522830°; 647 masl). This site is a transitional upper their endemism and conservation status. The availability evergreen forest. The observation post was established on of this updated ecological data is essential as a springboard an abandoned logging trail as a result of the destruction for setting conservation initiatives within this priority of the primary forest in the 1980s. What remained now conservation area. are old trees that were left by logging and new ones that have grown after the logging concession. Of all our survey sites in Maitum, this is the closest site to the pristine forest habitat in the Busa Mountain Range. METHODS Site 5: Sitio Boting, Brgy. Batian, Maitum (6.154700° 124.518460°; 294 masl). Sitio Boting is an inland Study Areas community located next to Boting river. The area is The southern slope of the Busa Mountain Range in landlocked by gorges and slopes. Much of the vegetation Sarangani Province is politically bordered by three in this area is similar to Site 1 whereby cleared areas municipalities – on the east, Kiamba at the mid- are planted with corn, coconut, and upland rice. Some center, and Maitum on the far west of the mountain range. portions of the forest are planted with “falcata” for timber Field visits were made to different forested localities harvesting. in Maitum and Kiamba (Table 1). At present, the PEF, Site 6: Lamlunay, Brgy. Upo, Maitum (6.11377° DENR RXII, and the Municipal Local Government Unit of 124.464789°; 60 masl). Lamlunay is a fragment of Maitum (MLGU Maitum) are closely working together to lowland evergreen forest separated by cultivated areas. declare the areas covered under the jurisdiction of Maitum The site is dominated by emergent trees such as “dao” as a Philippine eagle critical habitat (PECH), since these (Dracontomelon dao), “yakal” ( astylosa), and are both important hunting ground and nesting areas for “tanguile” (Shorea polysperma). Various species of the critically endangered Philippine eagle (Pithecophaga fruiting were also found to be abundant along the jefferyi) and are outside the declared KBA and LCA side of the stream. The forest floor in this area is thick in boundaries (Figure 1). dried leaf litters. Site 1: Batian Sentro, Maitum (6.141670° Site 7: Sitio Tulad, Brgy. Nalus, Kiamba (6.084166667° 124.514086°; 98 masl). This area is a low-lying 124.6511667°; 618 masl). The area is a mixed advanced community surrounded by undulating slopes of secondary secondary lowland evergreen forest with primary forest and primary lowland evergreen forest. Much of the patches mostly concentrated along riparian corridors and forested areas were cleared to give way for agriculture. in steep areas. The village is at the immediate base of Mt. The Batian river on the west and Boting river on the east Busa which is the merging point of two major streams confluence together in this area, which forms the Kalaneg flowing from the mountain down to the Panguil River. river that meanders on the community in the lowlands of Maitum. Site 8: Mt. Busa, Kiamba (6.105833333° 124.68195°;

348 Philippine Journal of Science Senarillos et al.: Birds of Busa Mountain Vol. 150 No. S1, Special Issue on Biodiversity Range, Sarangani, Philippines

Table 1. Survey sites within the Busa Mountain Range, Sarangani Province, Philippines. Locality Coordinates Elevation Survey period Barangay Batian Sentro, 6.141670° 124.514086° 98 masl 8–10 Aug 2018 Maitum Sitio Angko, Brgy. Batian, 6.155528° 124.491590° 495 masl 20–21 Jun 2020 Maitum Tambusong, Brgy. Batian, 6.168910° 124.499500° 384 masl 22–23 Jun 2020 Maitum Sankil, Brgy Batian, Maitum 6.166390° 124.522830° 647 masl 26–30 Jun 2020 Sitio Boting, Brgy. Batian, 6.154700° 124.518460° 294 masl 1–5 Jul 2020 Maitum Lamlunay, Brgy. Upo, Maitum 6.11377° 124.464789° 60 masl 11–12 Aug 2018 Sitio Tulad, Brgy. Nalus, 6.084166667° 124.6511667° 618 masl 6–8 Aug 2020 Kiamba Mt. Busa, Kiamba 6.105833333° 124.68195° 1,830 masl 9—11 Aug 2020 Sitio Banate, Brgy. Badtasan, 6.069966667° 124.6386333° 427 masl 12–13 Aug 2020 Kiamba Sitio Datal Bong, Brgy. 6.069533333° 124.6572167° 751 masl 13–14 Aug 2020 Tamadang, Kiamba

Figure 1. Map of the Busa Mountain Range showing the relative location of the study sites inside and outside the KBA 116.

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1,830 masl). The area is the upper montane forest of Mt. RESULTS Busa, Kiamba. It is characterized by a mix of stunted and tall hardwood trees. The forest floor is mostly covered A total of 116 species of birds were recorded for the with moss, bryophytes, and moist thick leaf litter. There Busa Mountain Range from both our field surveys are also ephemeral swamps and small streams. and secondary data (see Namocatcat et al. 2015). This record comprises 45 families and 88 genera (Table 2). Site 9: Sitio Banate, Brgy. Badtasan, Kiamba Of this value, 20 species are Mindanao endemics, 62 are (6.069966667° 124.6386333°; 427 masl). The area Philippine endemics, 51 are residents, two are migrants, is mostly dominated by abaca and agricultural crops. and one is introduced. The endemism value for bird Surrounding the village is an early secondary lowland assemblage in the area scores 53%, which means that for evergreen forest with a few primary forest trees along every 10 species encountered within the Busa mountain riparian areas. The area was hard hit during the logging range, five species are unique to the Philippines. Similarly, concession in the 1990s. a high endemism value of 32% for restricted-range species was calculated, which means that for every 10 Philippine Site 10: Sitio Datal Bong, Brgy. Tamadang, Kiamba endemic birds encountered, three species are confined (6.069533333° 124.6572167°; 751 masl). The highest in only to Mindanao. terms of elevation among the three villages surrounding Mt. Busa in Kiamba, Datal Bong is generally an open- The most frequently encountered bird species within the sites canopy area dominated by shrubs and grasses and is visited in Maitum and Kiamba were the Philippine serpent surrounded by lowland and montane forests. eagle (Spilornis holospilus), brahminy kite (Haliastur indus), white-eared (Phapitreron leucotis), yellow-breasted fruit dove (Ptilinopus occipitalis), plaintive (Cacomantis merulinus), rusty-breasted cuckoo SAMPLING METHOD (Cacomantis sepulcralis), ridgetop ( isonota), southern rufous ( mindanensis), Birds were accounted mainly through general observations writhed hornbill ( leucocephalus), with aid of binoculars and through calls. The species were Mindanao hornbill ( affinis), Philippine identified by morphology and distribution using the book, hanging /colasisi (Loriculus philippensis), hair- A Guide to the Birds of the Philippines (Kennedy et al. crested drongo (Dicrurus hottentottus), large-billed crow 2000). A combination of the point-count method along (Corvus macrorhynchos), elegant tit (Periparus elegans), a standard 2-km transect, “look and see” method from yellow-wattled (Pycnonotus urostictus), Philippine vantage points, and opportunistic listing was employed. bulbul ( philippinus), yellow-vented bulbul A total of 828 person-hr was spent for fieldwork between (Pycnonotus goiavier), white-eared tailorbird (Orthotomus August 2018 and August 2020. Most of our field surveys cinereiceps), coleto (Sarcops calvus), and red-keeled happened during the day between 0600H and 1700H, but ( australe). These species were opportunistic observations were also done at night time conspicuous and were easily identified because of their between 1800H and 2300H. distinct calls. The majority of species were encountered Secondary data was obtained from Namocatcat and fewer than 10 times during our field surveys. colleagues (2015), who pioneered the biodiversity inventory on the Kiamba side of the mountain range. Profile of Threatened Species Information on land use, exploitation for cage birds, A significant number of threatened species were recorded and hunting activities were also obtained from direct for the Busa Mountain Range. There were 16 threatened observations and from discussions with the local species under the International Union for the Conservation communities. The systematic , common names, of Nature (IUCN) Red List, of which 13 were species taxonomic treatment, and threatened status followed observed firsthand during our field surveys while three the Checklist of Birds of the Philippines, which follows species were recorded in the 2015 survey (Namocatcat et the International Ornithologists' Union World Bird List al 2015). One species is listed as Critically Endangered, 9.1 (Jensen et al. 2019). Mindanao endemics one as Endangered, seven species as Vulnerable, and seven are those species known only to occur in the Greater as Near Threatened. On the other hand, the DAO 2019- Mindanao region (Mindanao and Eastern endemic 09 listed five species as Critically Endangered, five as bird area), while accounts of conservation priority species Endangered, and nine as Vulnerable. The reasons of which were based on the Philippine Red List of Threatened may be attributed to the localized populations, intense Wildlife Fauna (DENR-BMB 2020). pressures on habitat owing to ongoing logging and forest loss, or both. The accounts of species with corresponding conservation status are provided below.

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Table 2. Checklist of bird species recorded in Busa Mountain Range, Sarangani Province, Philippines, including their residency and conservation status. Status Species Residency IUCN V 3.1 DAO 2019-09 Megapodiidae Megapodius cumingii Philippine R LC VU Phasianidae Gallus gallus Red junglefowl R LC OWS Accipitridae Pernis ptilorhyncus Crested honey buzzard R, M LC OWS Pernis steerei Philippine honey buzzard E LC OWS Spilornis holospilus Philippine serpent eagle E LC OWS Pithecophaga jefferyi Philippine eagle E CR CR Nisaetus pinskeri Pinsker’s hawk-eagle E EN EN trivirgatus Crested goshawk R LC OWS Haliastur indus Brahminy kite R LC OWS Rallidae Rallina eurizonoides Slaty-legged crake R LC OWS torquatus Barred R LC OWS Amaurornis olivacea Plain bush-hen E LC OWS Amaurornis phoenicurus White-breasted waterhen R LC OWS vitiensis Metallic pigeon R LC OWS Macropygia tenuirostris Philippine cuckoo-dove R LC OWS Geopelia striata Zebra dove R LC OWS Chalcophaps indica Common emerald dove R LC OWS Phapitreron leucotis White-eared brown dove E LC OWS Phapitreron amethystinus E LC CR Phapitreron brunneiceps E VU VU Ptilinopus occipitalis Yellow-breasted fruit dove E LC OWS Ducula poliocephala Pink-bellied E NT CR Cuculidae Centropus melanops Black-faced E LC OWS Centropus viridis Philippine coucal E LC OWS Eudynamys scolopaceus Asian koel R LC OWS xanthorhynchus Violet cuckoo R LC OWS Cacomantis merulinus Plaintive cuckoo R LC OWS Cacomantis sepulcralis Rusty-breasted cuckoo R LC OWS Surniculus velutinus Philippine drongo-cuckoo E LC OWS Cuculus optatus Oriental cuckoo M LC OWS Strigidae Otus gurneyi Giant scops E VU EN Otus everetti Everett's E LC OWS Otus mirus Mindanao scops owl E NT OWS Bubo philippensis Philippine eagle-owl E VU EN

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Status Species Residency IUCN V 3.1 DAO 2019-09 Tytonidae Tyto longimembris Eastern grass owl R LC OWS Caprimulgidae manillensis Philippine E LC OWS Apodidae amelis Ameline swiftlet E LC OWS Aerodramus whiteheadi Whitehead’s swiftlet E DD OWS Collocalia isonota Ridgetop swiftlet E NE OWS Collocalia troglodytes Pygmy swiftlet E LC OWS celebensis Purple needletail R LC OWS Mearnsia picina Philippine spine-tailed E NT VU Trogonidae ardens Philippine E LC OWS Alcedinidae Actenoides hombroni Blue-capped wood E VU VU smyrnensis White-throated kingfisher R LC OWS chloris R LC OWS Meropidae Merops philippinus Blue-tailed -eater R LC OWS Bucerotidae Buceros mindanensis Southern rufous hornbill E VU EN Rhabdotorrhinus leucocephalus Writhed hornbill E NT VU Penelopides affinis Mindanao hornbill E LC EN Megalaimidae Megalaima haemacephala Coppersmith barbet R LC OWS Picidae Dendrocopos maculatus Philippine pygmy E LC OWS javensis White-bellied woodpecker R LC OWS Chrysocolaptes lucidus Buff-spotted flameback E LC OWS Mulleripicus funebris Sooty woodpecker E NT OWS Falconidae Microhierax erythrogenys Philippine falconet E LC OWS Bolbopsittacus lunulatus Guaiabero E LC OWS Loriculus philippensis Philippine E LC CR Prioniturus discurus Blue-crowned racquet-tail E LC OWS Prioniturus waterstradti Mindanao racquet-tail E NT VU Pittidae Erythropitta erythrogaster Philippine pitta R LC OWS Pitta steerii Azure-breasted pitta E VU VU

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Status Species Residency IUCN V 3.1 DAO 2019-09 Campephagidae Coracina striata Bar-bellied cuckooshrike R LC OWS Malindangia mcgregori McGregor's cuckooshrike E LC VU Lalage melanoleuca Black-and-white triller E LC OWS Pachycephalidae Pachycephala homeyeri White-vented whistler R LC OWS Oriolidae steerii Philippine oriole E LC OWS Oriolus chinensis Black-naped oriole R LC OWS Dicruridae Dicrurus hottentottus Hair-crested drongo R LC OWS Rhipidura nigritorquis Philippine pied E LC OWS Rhipidura nigrocinnamomea Black-and-cinnamon fantail E LC OWS Monarchidae azurea Black-naped monarch R LC OWS Terpsiphone cinnamomea Rufous R LC OWS Corvidae Corvus macrorhynchos Large-billed crow R LC OWS Stenostiridae Culicicapa helianthea Citrine Canary-flycatcher R LC OWS Paridae Periparus elegans Elegant tit E LC OWS Pycnonotidae Pycnonotus urostictus Yellow-wattled bulbul E LC OWS Hypsipetes philippinus E LC OWS Pycnonotus goiavier Yellow-vented bulbul R LC OWS Hypsipetes everetti E LC OWS Phylloscopidae Phylloscopus olivaceus Philippine leaf warbler E LC OWS Megalurus palustris Striated grassbird R LC OWS Megalurus timoriensis Tawny grassbird R LC OWS sordidus Mindanao miniature babbler E DD OWS Orthotomus frontalis Rufous-fronted tailorbird E LC OWS Orthotomus cinereiceps White-eared tailorbird E LC OWS Timaliidae striaticeps Brown tit-babbler E LC OWS Zosteropidae Sterrhoptilus capitalis Rusty-crowned babbler E LC OWS Zosterops everetti Everett's white-eye R LC OWS Zosterops montanus Mountain white-eye R LC OWS

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Status Species Residency IUCN V 3.1 DAO 2019-09 Irenidae Irena cyanogastra Philippine fairy-bluebird E NT OWS Sittidae Sitta oenochlamys Sulphur-billed nuthatch E LC OWS Sturnidae Sarcops calvus Coleto R LC OWS Turdidae Turdus poliocephalus Island thrush R LC OWS Muscicapidae Cyornis ruficauda Rufous-tailed jungle flycatcher R LC OWS Ficedula westermanni Little pied flycatcher R LC OWS Eumyias panayensis Turquoise flycatcher R LC OWS Brachypteryx montana White-browed shortwing R LC OWS Ficedula luzoniensis Bundok flycatcher E LC OWS Chloropseidae Chloropsis flavipennis Philippine E VU CR Dicaeidae Dicaeum proprium E LC VU Dicaeum austral Red-keeled flowerpecker E LC OWS Dicaeum trigonostigma Orange-bellied flowerpecker R LC OWS Dicaeum hypoleucum E LC OWS Dicaeum ignipectus Fire-breasted flowerpecker R LC OWS Dicaeum pygmaeum E LC OWS Nectariniidae Anthreptes malacensis Brown-throated R LC OWS Leptocoma sperata Purple-throated sunbird E LC OWS Cinnyris jugularis Olive-backed sunbird R LC OWS pulcherrima Metallic-winged sunbird E LC OWS punctulata Scaly-breasted munia R LC OWS Lonchura leucogastra White-bellied munia R LC OWS Lonchura atricapilla R LC OWS Passeridae Passer montanus I LC OWS Motacillidae Motacilla cinereal Grey wagtail M LC OWS E – endemic; R – resident; M – migrant; I – introduced; CR – critically endangered; EN – endangered; VU – vulnerable; NT – near-threatened; OWS – other wildlife species; DD – data deficient; NE – not evaluated

Philippine megapode (Megapodius cumingii). With thresholds for Vulnerable under the population trend reference to the IUCN Red List, this ground-dwelling criterion. Despite these, the species is listed as Vulnerable resident species is listed as Least Concern on the basis in the DAO 2019-09, which may be due to the rapid of its very large range (extent of occurrence is > 20 000 degradation of its lowland forest habitats accompanied by km2) and population estimates that do not approach the hunting for local consumption. The elusive M. cumingii

354 Philippine Journal of Science Senarillos et al.: Birds of Busa Mountain Vol. 150 No. S1, Special Issue on Biodiversity Range, Sarangani, Philippines was observed foraging in the leaf litter of the forest floor (Nisaetus philippensis), from which it was recently split. It in Barangay Upo. is a medium-sized eagle with a longish, black crest that is uncommonly found in the forests from the lowland to over Philippine eagle (Pithecophaga jefferyi). The Philippine 1900 m (DENR-BMB 2020). With its main stronghold in eagles have already been documented many times in the Mindanao island, it is also affected by lowland habitat loss Busa Mountain Range. It was first documented in 1960 at and hunting. Among the birds found in the Busa Mountain Mt. Parker; a nesting pair was also discovered in Laconon Range, N. pinskeri ranks second to the Philippine eagle and Luhan, T’boli in 1985; and it was also documented in in terms of chances. Birdlife International Kiamba in April 1993 (BirdLife International 2001). In (2020b) believes that its global population is small, January 2017, an immature bird was rescued in Barangay between 600–800 matured individuals. We documented Batian, Maitum and was brought to the Philippine Eagle this species several times from 0900H–1300H in a mix Center for rehabilitation (Salvador et al. 2019). This of habitats in Barangay Batian from primary lowland individual named “Sarangani Pride” was fitted with a forest, secondary forest, and sometimes soaring in open GPS/GSM and radio transmitters before its release in landscapes adjacent to forest edges. The presence of an the forest of Barangay Batian in February 2017 (Figure adult and an immature bird in the area suggests that N. 2A). Recently, a subadult bird was rescued in Maasim, pinskeri shares the breeding territory with P. jefferyi within Sarangani in December 2019. In our survey in June 2020, the proposed PECH. It is listed as Endangered in the IUCN we recorded two adult birds soaring above the forests of Red List and DAO 2019-09. Sitio Angko and Sitio Boting in Barangay Batian. We suspect that these birds could be the resident breeding pair Amethyst brown dove (Phapitreron amethystinus). This that inhabits Barangay Batian as a nesting site. species is common locally in forest interior and edge up to 2000 m, singly or in pairs. In Mindanao, it tends to be It is important to note that all rescued Philippine eagles more common at elevations above 1000 m (DENR-BMB from the Busa Mountain Range have not yet reached 2020). Its larger bill, less conspicuous white “ear,” violet sexual maturity. This information suggests that these birds upper back, and cinnamon undertail coverts separates this are i) floaters or excess birds that are still looking for a species from the white-eared brown dove. Although this mate and a breeding territory of their own or ii) young Philippine-endemic species generally appears to have a eagles that have recently flown off the nest. This is a stable population size and occurs on several islands, it testament that Philippine eagles are continuously breeding is still listed as Critically Endangered in DAO 2019-09 in the mountain range. However, our knowledge of where due to the limited distribution of a presumably extinct and how many individuals are nesting still remains to be (P. amethystinus frontalis) in the island of limited since no active nest has ever been found in the . This species was documented during the point count slope of Sarangani Province despite the number of local survey in 2018 in Barangay Batian. sightings and anecdotal reports. Mindanao brown dove (Phapitreron brunneiceps). Given the large stretch of lowland evergreen forest in the Uncommon in lowland forest in and higher mountain range, it is possible that the Municipalities of elevation forests of Mindanao. It has a medium-sized Kiamba and Maasim have also a nesting pair of eagles body with generally brown body color and brown head that are yet to be discovered. This possibility opens for and neck with a glossy reddish-violet patch on side of an opportunity to conduct Philippine eagle expeditions the neck. It is distinct from amethyst brown-dove by the in these least explored areas in southern Mindanao to lack of white line below the eye, shorter bill, and greyer locate as many eagle nests as possible and implement underparts. Its small population continues to decline appropriate conservation measures. Since these sites are rapidly owing to the widespread reduction in forest ancient breeding sites and are used repeatedly by the pair cover within its distribution range, which is becoming across generations (Ibañez 2007). increasingly severely fragmented. In our surveys, we At present, an estimated 400 breeding pairs of this large detected P. brunneiceps twice – the first was in 2015 in forest raptor could be left in the forests of , , Barangay Batian during a transect walk and the second , and Mindanao (Bueser et al. 2003; Salvador and was in Sitio Tulad during the latest survey in August 2020. Ibañez 2006). However, with the very rapid decline of the This uncommon dove species was assessed as Vulnerable lowland forests and pressures exacerbated by hunting, the under the IUCN Red List and in DAO 2019-09. number of nesting pairs could be fewer than this estimated Pink-bellied imperial pigeon (Ducula poliocephala). It figure. The species was assessed as Critically Endangered is an endemic bird species to the Philippines and occurs in both the IUCN Red List and DAO 2019-09. on all major islands except for . The only large Pinsker’s hawk-eagle (Nisaetus pinskeri). It has a very pigeon with green breast and pinkish grey belly, it is similar appearance and habits to the Philippine hawk-eagle uncommon and found in second-growth and virgin forests

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Figure 2. Selected birds from the vicinity of the Busa Mountain Range: A) Philippine eagle “Sarangani Pride,” B) Mindanao hornbill (Penelopides affinis), C) Philippine falconet (Microhierax erythrogenys), D) Philippine serpent eagle (Spilornis holospilus), E) buff-spotted flameback (Chrysocolaptes lucidus), F) black-naped monarch (Hypothymis azurea), G) rufous paradise flycatcher (Terpsiphone cinnamomea), H) yellowish bulbul (Hypsipetes everetti), I) Philippine pitta (Erythropitta erythrogaster), and J) rufous-tailed jungle flycatcher (Cyornis ruficauda). up to 1500 m, singly or in small groups (DENR-BMB forests up to 670 m, with occasional records up to 1300 2020). Currently, there are no data available on population m, including mossy forest (DENR-BMB 2020). This owl trends, but the species is suspected to be declining at a has a small, declining, and fragmented populations as a moderately rapid rate due to the combined impacts of result of extensive deforestation. It is, therefore, listed heavy hunting pressure and extensive clearance of its as Vulnerable in the IUCN Red List and Endangered in preferred habitat on its populations. We did not observe the DAO 2019-09. This species was documented during this species in our surveys but were included in the 2015 our nocturnal survey for herpetofauna and non-volant list by Namocatcat and colleagues (2015). The IUCN Red mammals in Barangay Upo in August 2018. List listed D. poliocephala as Near Threatened; however, DAO 2019-09 listed it as Critically Endangered (CR). Philippine eagle-owl (Bubo philippensis). It is a large stocky endemic tufted owl that inhabits lowland and Giant scops owl (Otus gurneyi). This species is endemic secondary forests, often near rivers and lakes. It has two to the Philippines where it is known from Dinagat, distinct subspecies – the B. philippensis philippensis in , Samar, and Mindanao. This nocturnal raptor Luzon and and the larger B. philippensis inhabits primary, secondary, and selectively logged mindanensis in Mindanao, Samar, Leyte, and . dipterocarp forests. It primarily occurs in the lowland Owing to this species' requirement for lowland forest, it is

356 Philippine Journal of Science Senarillos et al.: Birds of Busa Mountain Vol. 150 No. S1, Special Issue on Biodiversity Range, Sarangani, Philippines suspected to have declined rapidly due to lowland forest DAO 2019-09, as it is suspected to be declining rapidly conversion within its distributional range. However, it can throughout its range as a result of habitat loss and hunting. persist in some modified habitats, suggesting tolerance to Within all the surveyed sites in the mountain range, this disturbance; thus, further research is required to compare species is fairly common in flocks of about six individuals population densities among different habitats and the effect foraging along riparian habitats. of the current deforestation rates on its populations. In the latest assessment, B. philippensis is listed as Vulnerable in Writhed hornbill (Rhabdotorrhinus leucocephalus). the IUCN Red List and Endangered in the DAO 2019-09. Similar to other hornbill species observed, populations This species was not seen, but calls were heard several times of this poorly known endemic species are also declining around Sitio Tulad in Kiamba, Sarangani. rapidly due to habitat loss and hunting. This species occurs in the forests of Mindanao and the adjacent Philippine spine-tailed swift (Mearnsia picina). This is Sur and between 300–1,000 masl an uncommon species endemic to Visayas and Mindanao. (DENR-BMB 2020). The population size of this species Less observed over or near the forest, it usually flies at has not been quantified but it is generally considered a medium heights and occasionally close to the ground in rare species. It is listed as Near Threatened in the IUCN mountain passes or down logging roads in the forest. It is Red List and Vulnerable in the DAO 2019-09. The Busa distinguished by its very long and uniquely shaped wings, Mountain Range likely has a good breeding population a short body that is mostly black with metallic blue gloss, of this species since it was observed fairly common in a distinctive short tail with 1-mm spine-like extensions, the area, particularly in Barangays of Batian and Upo in white throat, and white patches in armpits (DENR-BMB Maitum, and Nalus, Badtasan, and Tamadang in Kiamba. 2020). The species has a small yet decreasing population and a limited distribution. It is threatened by the rapid loss Mindanao hornbill (Penelopides affinis). This is a and degradation of lowland forests habitat. Individuals small hornbill endemic to Greater Mindanao with of this species were only recorded along forest edges in three subspecies: affinis for Mindanao (Figure 2B) Barangay Batian mixed-feeding with ameline swiftlet (Bucas, Dinagat, Siargao), basilanica for Basilan, and (Aerodramus amelis), ridgetop swiftlet (Collocalia samarensis for Eastern Visayas (Samar, Leyte, Bohol, isonota), pygmy swiftlet (Collocalia troglodytes), and , Calicoan). This species mainly inhabits forests purple needletail (Hirundapus celebensis). below 1500 m (DENR-BMB 2020). It is distinguished from writhed and rufous , which co-occur Blue-capped wood kingfisher (Actenoides hombroni). in the area, by its small size, and trumpeting calls. Its It is a moderately-sized bird known only to inhabit the limited distribution within its restricted range and a understory stratum of primary and secondary-growth rapidly declining population due to the ongoing habitat mid-montane and mossy forests from 1000–2000 m on a destruction and hunting for food qualifies this species in few mountain massifs of Mindanao Island (including Apo, a threatened category. Throughout the mountain range, P. Busa, Hilong-hilong, Kitanglad, and Pasian) (DENR-BMB affinis was the most abundant species, with flocks reaching 2020). This uncommon kingfisher is commonly found in into numbers of 15 individuals from 0500H–1700H. It is streams. Its highly restricted range, limited occupancy, listed as Least Concern in IUCN Red List, but the DAO and the continued degradation of montane habitats due 2019-09 listed it as Endangered. to encroachment qualify this species as Vulnerable under the criterion C2a(i) in the IUCN Red List and in the DAO Philippine hanging parrot (Loriculus philippensis 2019-09. This species was not documented in this survey apicalis). This is the smallest Philippine parrot that is but was captured in the mist net established in the lower commonly found in all forest types, including montane montane forest during the biodiversity assessment in forests. It also occurs in urban areas, particularly in Kiamba (Namocatcat et al. 2015). green spaces in the cities. It is easily distinguished by a red color on its head and rump. It feeds on flowers and Southern rufous hornbill (Buceros mindanensis). This nectar, especially from and bananas. Ten (10) species is endemic to the Philippines and known to occur races are known from the Philippines and are endemic on nine islands: Samar, Leyte, Bohol, Panaon, Biliran, to their respective localities. The Cebu (chrysonotus) Calicoan, and Buad (race semigaleatus), Dinagat, Siargao, and (mindorensis) subspecies are very rare, Mindanao (plus Balut, Bucas, and Talicud), and Basilan. explaining the Critically Endangered status in the DAO This species occurs largely from primary lowland evergreen 2019-09. This subspecies is locally common in the Busa forests to montane forests up to 2100 m (DENR-BMB Mountain Range and is commonly captured as house pets 2020). This species appears tolerant of disturbance, as it is in local communities adjacent to forested areas. known locally to inhabit mature secondary and selectively- logged forests. This forest-dependent species is listed as Mindanao racquet-tail (Prioniturus waterstradti). Vulnerable in the IUCN Red List and Endangered in the Endemic to Mindanao, it inhabits the humid montane

357 Philippine Journal of Science Senarillos et al.: Birds of Busa Mountain Vol. 150 No. S1, Special Issue on Biodiversity Range, Sarangani, Philippines forests of only nine localities. Similar to other racquet- Whiskered flowerpecker (Dicaeum proprium). Endemic tails, they are noisy in flight and they build their nests to Mindanao, this species inhabits primary and secondary 5–7 m above the ground. The lack of blue in the crown growth forests from 800–900 m (DENR-BMB 2020). distinguishes it from the lowland blue-crowned Racquet- Despite its tolerance to disturbance, forest loss is assumed tail. The few locations where it occurs severely limit to have had some impact at the lower limit of its altitudinal the population size, which is further undergoing some range. The global population size has not been quantified, but decline owing to habitat loss. This is exacerbated by the species is described as uncommon to locally common in hunting for the pet trade, which remains one of the major forest edges. In all the surveyed sites, D. proprium was only threats to this species. These likely are the reasons for its documented in Tambusong. At present, this flowerpecker is enlistment as Near Threatened in the IUCN Red List and listed as Vulnerable in the DAO 2019-09. Vulnerable under the DAO 2019-09. The P. waterstadti is locally common in Mount Busa, Kiamba in altitudes Species and Habitat Conservation Issues above 1,600 masl. The forests of southern Mindanao declined to more Azure-breasted pitta (Pitta steerii). Endemic to Samar, than 50% of the region’s forest cover in the early 1990s Leyte, Mindanao, and small adjacent islands, this species (DENR-FMB 2018). The last remaining intact forests is less commonly encountered. It is shy and is best located in the region are mostly confined to the Busa Mountain by its call, frequently after the rain and usually from an Range (and KBA 116), which are mostly vulnerable to elevated perch. This pitta is distinguished by its black various anthropogenic threats such as agriculture, illegal head, white throat, green upperparts except for shining logging, and timber poaching (DENR 2020). In our azure-blue rump and wing patch, pale blue underparts, surveys, we observed that several of the local communities black patch on center of belly that merges into a vivid adjacent to the Busa Mountain Range are primarily scarlet lower belly, undertail-coverts, greyish-flesh legs, dependent on agricultural crops such as corn, abaca, and and stout, dark bill. This pitta is listed as Vulnerable in the other minor forest products, including bamboo and rattan, IUCN Red List and in DAO 2019-09 due to its small and which they harvest to make thatched materials. severely fragmented population, which is likely rapidly The practice of kaingin and shifting cultivation were declining due to the loss of lowland forests. P. steerii was also common in the study areas, particularly in lower not observed in this survey but included in the previous elevations. If not controlled, these practices might list of Namocatcat and colleagues (2015) in Kiamba. encroach on forested areas that are classified as protection McGregor's cuckooshrike (Coracina mcgregori). This forests, which could fragment and degrade pristine forest Mindanao-endemic cuckoo- inhabits montane habitat in the mountain range. Abandoned logging trails forests between 1,000–1,900 masl (DENR-BMB 2020). It were also present, which pose threats since these increases also occurs along the forest edge. It is listed as Vulnerable human access to the forest and further fragmentation. in DAO 2019-09 due to the substantial habitat loss within All these issues are identified as the principal long-term its existing range. In this survey, a single individual was threats to the biodiversity in the mountain range. observed in Barangay Nalus, Kiamba between 1,400– Bushmeat hunting and wildlife collection for pet trade 1,600 masl together with black-and-cinnamon fantail were also observed in the areas surveyed. A number of (Rhipidura nigrocinnamomea). locals were engaged in hunting Philippine warty pigs (Sus Philippine leafbird (Chloropsis flavipennis). Endemic to philippensis) and larger species of birds. In one instance, the Philippines, this species is known only from Samar, a local hunter was encountered carrying a freshly killed Leyte, Cebu, and Mindanao. It is distinguished by its southern rufous hornbill (B. mindanensis) for subsistence predominantly lime-green body color (darker above than during our field survey in Sankil, Barangay Batian. below), yellow-green lores, eyering, and a greenish- Several local houses also keep birds in cages that include yellow throat and outer edges to primaries. Its bill has white-eared brown dove (P. leucotis) and Philippine a dark horn that is lighter at the tip and on the cutting hanging parrot (L. philippensis). A human habituated edge. This species inhabits primary forest, but it is also immature Philippine serpent eagle (S. holospilus), which observed in secondary forests and degraded habitats was likely removed from its nest, was also documented. below 1000 m (DENR-BMB 2020). A rapid and on-going All these activities are significant short-term threats to the decline of its population is suspected to be occurring due wildlife in the Busa Mountain Range that may contribute to the extensive loss and degradation of lowland forests to the continuing decline of the many threatened species throughout its range. It is listed as Vulnerable in the IUCN recorded in the area if left unregulated. Red List and Critically Endangered in the DAO 2019-09. Efforts to address these issues were primarily undertaken This species was documented in both the Maitum and in by the DENR-CENRO (Community Environment & Kiamba portions of the Busa Mountain Range.

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Natural Resources Office) Kiamba. With its National Conversely, 57 bird species that were not recorded in the Greening Program, the office implements sustainable 2015 study of Namocatcat and colleagues were added management of natural resources through resource to the list – namely, Philippine megapode (Megapodius conservation, protection, and productivity enhancement. cumingii), red junglefowl (Gallus gallus), crested honey These activities were mostly focused on planting fruit buzzard (Pernis ptilorhyncus), Philippine honey buzzard trees and other fast-growing species and conducting (Pernis steerei), Philippine eagle (Pithecophaga jefferyi), communication, education, and public awareness Pinsker's hawk-eagle (Nisaetus pinskeri), barred rail campaigns to the upland communities. The DENR – (Gallirallus torquatus), zebra dove (Geopelia striata), together with the MLGU Maitum, through its Municipal plain bush-hen (Amaurornis olivacea), common emerald Environment and Natural Resources Office – also dove (Chalcophaps indica), Mindanao brown dove organized forest guards to conduct monthly patrolling in (Phapitreron brunneiceps), black-faced coucal (Centropus selected areas in the Busa Mountain Range to apprehend melanops), Asian koel (Eudynamys scolopaceus), violet illegal hunters and loggers. cuckoo (Chrysococcyx xanthorhynchus), Philippine drongo-cuckoo (Surniculus velutinus), giant scops owl With the declaration of the southern slope of the Busa (Otus gurneyi), Everett's scops owl (Otus everetti), Mountain Range as an LCA, the MLGU Maitum, DENR- Eastern grass own (Tyto longimembris), Philippine CENRO Kiamba, and DENR RXII, with assistance from nightjar (Caprimulgus manillensis), ameline swiftlet the USAID Protect Wildlife Project, is preparing to (Aerodramus amelis), whitehead’s swiftlet (Aerodramus include the southern slope of the Busa Mountain Range whiteheadi), purple needletail (Hirundapus celebensis), in the expanded national integrated protected area system Philippine spine-tailed swift (Mearnsia picina), Philippine (ENIPAS). The northern slope of the mountain range is trogon (Harpactes ardens), white-throated kingfisher already within the proposed strict protection zone (SPZ) (Halcyon smyrnensis), collared kingfisher (Todiramphus of the Allah Valley Protected Landscape in the Provinces chloris), blue-tailed bee-eater (Merops philippinus), of South Cotabato and (DENR 2020). buff-spotted flameback (Chrysocolaptes lucidus), Philippine falconet (Microhierax erythrogenys), guaiabero (Bolbopsittacus lunulatus), blue-crowned racquet- tail (Prioniturus discurus), Mindanao tacquet-tail DISCUSSION (Prioniturus waterstradti), Philippine pitta (Erythropitta The pioneering study of Namocatcat and colleagues erythrogaster), Philippine oriole (Oriolus steerii), (2015) provided an initial taxonomic listing of birds McGregor's cuckooshrike (Coracina mcgregori), observed in Sitio Tulad, Barangay Nalus, Kiamba. black-naped oriole (Oriolus chinensis), Philippine pied Fifty-nine (59) species of birds comprising 49 genera fantail (Rhipidura nigritorquis), black-and-cinnamon under 30 families were accounted. There were 18 species fantail (Rhipidura nigrocinnamomea), black-naped from the previous list which were not observed in our monarch (Hypothymis azurea), Philippine leaf warbler field surveys. These were white-breasted waterhen (Phylloscopus olivaceus), striated grassbird (Megalurus (Amaurornis phoenicurus), metallic pigeon (Columba palustris), rufous-fronted tailorbird (Orthotomus vitiensis), pink-bellied imperial pigeon (Ducula frontalis), brown tit-babbler (Macronus striaticeps), poliocephala), oriental cuckoo (Cuculus optatus), Everett's white-eye (Zosterops everetti), Philippine Mindanao scops owl (Otus mirus), blue-capped wood fairy-bluebird (Irena cyanogastra), island thrush (Turdus kingfisher (Actenoides hombroni), Philippine pygmy poliocephalus), rufous-tailed jungle flycatcher (Cyornis woodpecker (Dendrocopos maculatus), white-bellied ruficauda), turquoise flycatcher (Eumyias panayensis), woodpecker (Dryocopus javensis), sooty woodpecker fire-breasted flowerpecker (Dicaeum ignipectus), (Mulleripicus funebris), azure-breasted pitta (Pitta brown-throated sunbird (Anthreptes malacensis), steerii), black-and-white triller (Lalage melanoleuca), purple-throated sunbird (Leptocoma sperata), olive- white-vented whistler (Pachycephala homeyeri), citrine backed sunbird (Cinnyris jugularis), metallic-winged canary-flycatcher (Culicicapa helianthea), Mindanao sunbird (Aethopyga pulcherrima), scaly-breasted munia miniature babbler (Micromacronus sordidus), rusty- (Lonchura punctulate), white-bellied munia (Lonchura crowned babbler (Sterrhoptilus capitalis), little pied leucogastra), Eurasian tree sparrow (Passer montanus), flycatcher (Ficedula westermanni), white-browed and grey wagtail (Motacilla cinereal). shortwing (Brachypteryx montana), and bundok The significant increase of bird species recorded could flycatcher (Ficedula luzoniensis). The cryptic nature be attributed to the higher number of surveyed sites (10 and the limited survey efforts on habitats where these localities, Figure 1), covering a wide range of elevation birds are found could be the primary reason why the (60 masl–1,830 masl) and habitat types (agriculture areas, aforementioned species were not detected. lowland, and montane forests), higher sampling effort

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(828 person-hr), and a combination of several sampling Bagobo babbler (Leonardina woodi), striated wren- methods (line transects, point counts, opportunistic listing, babbler (Ptilocichla mindanensis), long-tailed bush “look and see,” and literature review). These increased the warbler (Locustella caudata), cryptic flycatcher (Ficedula sampling coverage of our study compared to Namocatcat crypta), short-crested monarch (Hypothymis helenae), and colleagues (2015), who focused on the inventory of celestial monarch (Hypothymis coelestis), short-tailed birds only in Sitio Tulad, Barangay Nalus, Kiamba from (Aplonis minor), olive-capped flowerpecker 25–27 Apr 2015. (Dicaeum nigrilore), flame-crowned flowerpecker (Dicaeum anthonyi), grey-hooded sunbird (Aethopyga Most of our sampling areas were within the forest edges primegenius), Apo sunbird (Aethopyga boltoni), cinnamon in the lowland near agricultural plantations, in secondary ibon (Hypocryptadius cinnamomeus), and red-eared and primary lowland, and a few in montane habitats. parrot-finch (Erythrura coloria). The proximity of forest edges to intact forested areas may explain the high bird assemblage recorded in our study sites (Tanalgo et al. 2015). We also employed a mix of different methods, which enabled us to document CONCLUSION AND more bird species, such as the “look and see” method technique that is specific in documenting raptors and RECOMMENDATIONS other canopy-dwelling species. This approach allowed Despite the limited survey effort, the results clearly indicate us to successfully document several species of raptors, that the Busa Mountain Range harbors a rich assemblage of including the critically endangered Philippine eagle. bird species hinting at the substantial level of biodiversity For the ground-dwelling and understory bird species, this mountain range hosts. More importantly, this area the standard point-count method along a standard 2-km houses a significant number of species threatened with transect and opportunistic listing were employed. extinction which is of high priority for conservation. Our results also highlight the Busa Mountain Range as one of the Our results suggest that bird diversity is higher in areas remaining strongholds of the Philippine Eagle population with complex vegetation diversity such as primary and in southern Mindanao, which reinforces and justifies the secondary forests, which explain the dominance of ongoing efforts to include the mountain range in ENIPAS lowland elevation species in the list, with only a few as a protected area. species specializing in montane and mossy forest habitats. The land area, geometric constraints, climate, food We, therefore, recommend that additional field availability, and productivity may explain the distribution surveys should be conducted in other parts of the Busa of these bird species among the different forest types in Mountain Range, particularly in areas that have never the Busa Mountain Range (He et al. 2019). been biologically explored, to minimize bias against unaccounted and highly cryptic species. Research studies The present list is the first information for the avian fauna should also focus on a wider number of equally important in the Busa Mountain Range. Thorough exploration in the threatened and endemic taxa. Many of the threatened and mountain range, particularly in the northern slope, would endemic birds we observed require more conservation likely increase our current estimate. With respect to the attention, as these are poorly known and are mainly similarity of mountain structure, elevation, and habitat thriving in the forests below 800 m (e.g. Pinsker’s hawk- types of the Busa Mountain Range from other neighboring eagle, pink-bellied imperial pigeon, giant scops owl, mountain ranges, the following species could also be Philippine eagle-owl, and Philippine leafbird). present in the area: Mindanao bleeding-heart pigeon (Gallicolumba crinigera), Philippine green pigeon (Treron Recovery measures such as reforestation activities using axillaris), spotted imperial pigeon (Ducula carola), great native tree species and the development of sustainable eared nightjar (Lyncornis macrotis), whiskered farming methodologies will ensure the continued (Hemiprocne comate), Asian palm swift (Cypsiurus persistence of the lowland forest, which is an important balasiensis), rufous-lored kingfisher (Todiramphus habitat for many wildlife species. Lastly, we recommend winchelli), Philippine dwarf kingfisher (Ceyx melanurus), exploring areas with historic and recent Philippine eagle dimorphic dwarf kingfisher (Ceyx margarethae), records to locate nesting sites and determine breeding southern silvery kingfisher (Ceyx argentatus), Mindanao density for the entire Busa Mountain Range. From this lorikeet (Trichoglossus johnstoniae), wattled broadbill information, we could identify high conservation priority (Sarcophanops steerii), long-tailed shrike ( areas, which can be an important consideration in the schach), white-breasted woodswallow (Artamus future developments for the conservation of the Busa leucorynchus), black-bibbed cuckooshrike (Coracina Mountain Range. This action is a step forward for the long- mindanensis), mountain shrike (Lanius validirostris), term conservation and protection of the few remaining stripe-breasted rhabdornis (Rhabdornis inornatus), primary forest blocks in southern Mindanao.

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ACKNOWLEDGMENTS DICKINSON EC, KENNEDY RS, PARKES KC. 1991. The birds of the Philippines: an annotated check-list Many people helped us in this project; we offer our sincere (Check-list 12). British Ornithologists’ Union, London. thanks to all. We acknowledged For. Jessica C. Guilao, Ms. Maria Tubera, and Mr. Edgar Q. Calderon of DENR- HE X, WANG X, DUBAY S, REEVE AH, ALSTROM CENRO Kimba and Mr. Ronaldo D. Lacanaria and For. P, RAN J, LIU Q, WU Y. 2019. Elevational patterns Abdul Ghaffur A. Domanday of DENR RXII for their of bird species richness on the eastern slope of Mt. assistance in the field. We thank Ms. Beth N. Ramos and Gongga, Sichuan Province, . Avian Research Municipal Environment & Natural Resources Officer 10: 1. Nannette Ramirez Nacional for providing logistical IBAÑEZ JC. 2007. Philippine Eagle Pithecophaga jefferyi support and a warm welcome to the Municipality of breeding biology, diet, behavior, nest characteristics Maitum. We also thank Philippine Eagle Foundation and longevity estimate in Mindanao Island [MS The- Forester and Geographic Information System Officer sis]. Ateneo de Davao University, Davao City, Philip- Guiller Opiso for helping us with the maps. Lastly, we pines. 109p. (Available at ADDU Library) are extremely grateful to Dr. Ali M. Hadjinasser, CENR Officer-in-Charge of DENR-CENRO Kiamba, and to Atty. JENSEN A, ALLEN D, HUTCHINSON R, PEREZ C, Felix S. Alicer, Regional Executive Director of DENR VAN DE VEN W, BRINKMAN JJ. 2019. Checklist RXII for their encouragement and continued support in the of birds of the Philippines. Wild Bird Club of the conservation work. Two anonymous reviewers improved Philippines. Retrieved on 10 Jul 2020 from www. the early version of the manuscript. This fieldwork was birdwatch.ph funded by the Whitley Fund for Nature. KENNEDY RS, GONZALES PC, DICKINSON EC, MI- RANDA HC, FISHER TH. 2000. A guide to the birds of the Philippines. Oxford: Oxford University Press. REFERENCES NAMOCATCAT JA, REQUIERON E, REMOLLO L, CARIÑO A, VENDIOLA R. 2015. Rapid biodiversity BIRDLIFE INTERNATIONAL. 2001. Threatened birds assessment of Mt. Busa, Municipality of Kiamba, of Asia: the BirdLife International Red Data Book. Sarangani Province. Environmental Conservation Cambridge, UK. and Protection Center & Mindanao State University BIRDLIFE INTERNATIONAL. 2020a. Important Bird – . 48p. Areas factsheet: Mount Busa-Kiamba. Retrieved on ONG PS, AFUANG LE, ROSELL-AMBAL RG. 2002. 10 Jul 2020 from http://www.birdlife.org Philippine Biodiversity Conservation Priorities: A Sec- BIRDLIFE INTERNATIONAL. 2020b. Species factsheet: ond Iteration of the National Biodiversity Strategy and Nisaetus pinskeri. Retrieved on 23 Sep 2020 from Action Plan. Department of Environment and Natural http://www.birdlife.org Resources – Protected Areas and Wildlife Bureau, Conservation International Philippines, University of BUESER GL, BUESER KG, AFAN DS, SALVADOR DI, the Philippines Center for Integrative and Develop- GRIER JW, KENNEDY RS, MIRANDA HC. 2003. ment Studies – Biodiversity Conservation Program, Distribution and nesting density of the Philippine Eagle and Foundation for the Philippine Environment. 113p. Pithecophaga jefferyi on Mindanao Island, Philippines: what do we know after 100 years? Ibis 145: 130–135. PERALTA CV. 2020. Mt. Busa of Sarangani Declared as Local Conservation Area. Retrieved on 23 Aug [DENR] Department of Environment and Natural Re- 2020 from https://www.mindanews.com/minda- sources. 2020. Allah Valley Watershed Forest Reserve views/2020/03/mindanawon-abroad-glasshouses mt- Protected Area Suitability Assessment. Office of the busa-of-sarangani-declared-as-local-conservation- Protected Area Superintendent of the Allah Valley area/ Protected Landscape, PENRO South Cotabato. 74p. ROBSON C, DAVIDSON P. 1996. Some Recent records [DENR-BMB] Department of Environment and Natural of Philippine birds. Forktail: Journal of the Oriental Resources – Biodiversity Management Bureau. 2020. Bird Club No. 11. Philippine Red List of threatened wild fauna PART I – VERTEBRATES. City, Philippines. SALVADOR DI, IBAÑEZ JC, SENARILLOS TLP. 2019. Death by a Thousand Cuts: Human Persecution of the [DENR-FMB] Department of Environment and Natural IUCN “Critically Endangered” Philippine Eagles in Resources – Forest Management Bureau. 2018. Philip- the Republic of the Philippines. Proceedings of the pine forestry statistics. 95p. Retrieved on 02 Dec 2020 11th Asian Raptor Research & Conservation Network from http://forestry.denr.gov.ph/

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