Volume 17 Issue 1 - 2023 | 29
© Association of Systematic Biologists in the Philippines
1Department of Environment and Natural Resources - Provincial Environment and Natural Resources Office South Cotabato, Koronadal City 9506, Philippines
2World Bank East Asia and Pacific Gender Innovation Lab, Washington, D.C. 20433, USA
3School of Graduate Studies, Mindanao State University - General Santos, General Santos City 9500, Philippines
4Philippine Eagle Foundation Inc., Philippine Eagle Center, Malagos, Baguio District, Davao City 8000, Philippines
5Hawk Mountain Sanctuary, 410 Summer Valley Road, Orwigsburg, PA 17961, USA
6Big Year Davao, Inc., Davao City 8000, Philippines
*Corresponding author: [email protected] Date Submitted: 13 February 2023
Date Accepted: 02 January 2024 Date Published: 19 January 2024 Introduction
The complex geological history of the Philippine archipelago largely contributes to the present-day diversity and endemism in the country. Recent and paleoendemic lineages of vertebrate wildlife have persisted and diversified via several evolutionary processes, including ancient geological movements, fluctuating sea levels during the Pleistocene, and topographic complexities of the islands (Heaney 1986; Brown et al. 2013). Targeted fieldwork over the years in remaining forested habitats in the Philippines along with the use of integrative taxonomic approaches (e.g., using morphological, molecular, ecological, and behavioral data for species descriptions) have improved our understanding of wildlife diversity patterns in the country, particularly in relatively less explored areas of Mindanao. This large island is a composite of oceanic and continental landmasses that contributes to its topographical complexity (Sajona et al. 1997; Hall 2002;
Abstract
Mount Melibengoy is a partially protected key biodiversity area in southern Mindanao, Philippines faced with many anthropogenic pressures. Pushing for the holistic and evidence-based protection of this mountain requires reports on empirical biodiversity data, which are currently limited for the area. To augment this information, we conducted opportunistic field surveys between September 2020 and August 2022 and collated related data to generate a list of avian fauna in Mt Melibengoy that would serve as baseline for informed management interventions and future research. We recorded 130 avian species from 49 families and 104 genera, of which 68 species are considered Philippine endemics and 19 species are only found on Mindanao, including the rarely observed Mindanao lorikeet (Saudareous johnstoniae). The presence of several avian species of scientific and conservation importance requires immediate attention from concerned stakeholders to address habitat modifications and disturbances occurring in portions within and outside the Protected Area. Albeit preliminary, our results provide the much-needed evidence to justify the immediate protection of the unprotected forests of Mt Melibengoy and strengthen its already existing management mechanisms.
Keywords: birds, Lake Holon, Mindanao lorikeet, NIPAS, protected areas
Kier Mitchel E. Pitogo1*, Forest Jarvis2, Aljohn Jay L. Saavedra1,3, Tristan Luap Senarillos4, Camille B. Concepcion5 and Peter M. Simpson6
Avian fauna of Mount Melibengoy, southern Mindanao,
Philippines: conservation implications on a partially protected key biodiversity area under threat
Yumul et al. 2004), many of which are mountain ranges that are still biologically underexplored.
Recent wildlife studies in Mindanao have increased our appreciation of the rich and unrecognized vertebrate wildlife diversity on the island that are needing more scientific and conservation attention (Sanguila et al. 2016; Hosner et al.
2018; Gracia et al. 2021; Pitogo et al. 2021; Senarillos et al.
2021; Rowsey et al. 2022). Unfortunately, 70% of Mindanao’s key biodiversity areas (KBAs)—identified because of their high biodiversity potential—are currently not included in the Philippine National Integrated Protected Areas System (NIPAS; Mallari et al. 2016). Since not covered under national law and with weaker environmental management measures in place, these areas are more vulnerable to landcover changes brought about by agricultural expansion and human settlements (see Bailey et al. 2016). As reported by the Global Forest Watch, Mindanao lost ca. 5,137,100 km2 of forest cover from 2001 to 2022. Suitable habitats for many wildlife species reliant on forested areas will eventually decrease if unabated forestland conversion continues in the island and appropriate protection of remaining KBAs are not pursued.
Avian fauna are among the most vulnerable to forest cover loss in the Philippines (Rabor 1959; Collar et al. 1999;
Brooks et al. 2001). This is especially true for forest-dependent endemic species with narrower niche breadth, smaller elevational ranges, and larger body sizes (Sodhi et al. 2010;
Kittelberger et al. 2021). Poor avian diversity is detrimental to any habitat as birds provide essential ecosystem services as seed dispersers, biological pest control agents, important predators, and scavengers (Whelan et al. 2016). Therefore, birds serve as an ideal taxon for monitoring localized environmental changes since they are sensitive to habitat disturbances (Järvinen & Väisänen 1979; Canterbury et al.
2000), especially in montane environments where the impacts of habitat changes on avian communities are compounded by
the effects of climate change (Harris et al. 2014; Srinivasan &
Wilcove 2021).
Mindanao is the most species-rich in the Philippines in terms of avian diversity, hosting more than half of its 255 endemic avian species, with at least 23 species unique only to the island; the majority of which inhabit and breed in montane forests (Kennedy et al. 2001; Allen 2020; Brinkman et al.
2022). The lack of targeted avian surveys on mountains in Mindanao, particularly in the southern portion, has limited our general knowledge and understanding of their biodiversity and distribution patterns (Senarillos et al. 2021). This knowledge shortfall may impede progress on habitat conservation and protection due to the lack of usable empirical species data, as these justify habitat protection measures (Pitogo et al.
2021; Senarillos et al. 2021), informed species conservation assessment and planning (Margules & Pressey 2000; Gonzalez et al. 2018), and complement existing conservation efforts (Tanalgo et al. 2019; Garcia et al. 2021). Thus, there is a need to produce baseline empirical and site-specific biodiversity data to facilitate such conservation measures, not to mention that this would help address the knowledge gaps in species distribution, which is more pronounced locally (Hortal et al.
2015).
One of the major mountains in southern Mindanao that needs basic biodiversity science research is Mt Melibengoy (formerly known as Mt Parker or Parker volcano), geologically a Quaternary andesitic-dacitic volcano with a 3-km wide caldera occupied by Lake Holon (formerly known as Lake Maughan) at the base (Delfin Jr et al. 1997). It is located east of the Busa Mountain Range (BMR) and together comprises the Mt Busa Key Biodiversity Area (KBA 196). This KBA is partially protected as the northern slopes of the BMR and northwestern portion of Mt Melibengoy are within the Allah Valley Protected Landscape (AVPL), leaving the rest of the KBA unprotected and vulnerable to land-use changes. Despite some legal framework for its protection, Mt Melibengoy is
faced with threats of forest clearing, alien invasive species, poaching, and habitat disturbances from its growing tourism.
These threats are much more pronounced outside AVPL and are exacerbated by road development, which bisects the once- contiguous huge block of primary forests of Mt Melibengoy and Malibato mountain range.
The presence of globally threatened and restricted-range bird species in Mt Melibengoy, and the whole of KBA 196, makes it an Important Bird Area (IBA; BirdLife International 2022). Our knowledge of avian fauna of Mt Melibengoy is largely derived from early museum records (Collar et al.
1999), publicly available databases (e.g., eBird 2022), and available comprehensive bird guides (Kennedy et al. 2001;
Allen 2020). However, this available yet scattered information is of limited application to influence conservation outcomes unless streamlined and reported for public and scientific uses.
With this, and cognizant of the need to push for the evidence- based protection of this conservation priority site, we conducted opportunistic bird surveys in Mt Melibengoy and collated related information to readily inform conservation and management interventions for this mountain. Albeit preliminary, this paper provides the much-needed report of avian fauna—the first account of vertebrate wildlife—in this fragile montane habitat, an urgent response to helping address the conservation challenges in this partially protected key biodiversity area under threat.
Material and Methods Study Area
Mt Melibengoy is under the jurisdiction of the Municipality of Tboli, South Cotabato Province. It is the southernmost on-shore volcano in southcentral Mindanao, which is covered by old-growth montane forests. The waters from the northwestern slope of the mountain flow through the Allah River watershed, and thus included in the boundaries of AVPL, an initial component of the NIPAS. The remaining
Figure 1. Map showing the relative location of Mt Melibengoy and its portions within the Allah Valley Protected Landscape (AVPL, blue line). A concrete road (white line) bisects the once-contiguous primary forests of Mt Melibengoy and the adjacent Malibato mountain range.
Philippine Journal of Systematic Biology Online ISSN: 2508-0342 forested areas of Mt Melibengoy and neighboring mountains feed into the Sapali, Silway, Makar, and Nobol rivers, making it an important and critical watershed area. It is both an IBA and KBA, as well as an extremely high conservation priority site in the Philippines (Ong et al. 2002).
Fieldwork was conducted along the Nabul and Kule trails in Barangay Salacafe, which is within the AVPL (Fig.
1). These areas are the primary entry points of Mt Melibengoy leading to the most-visited Lake Holon, an emerging birding hotspot in the country (Allen 2020). Tourists and locals traverse the mountain using both trails. The Philippine Department of Environment and Natural Resources (DENR) also established their biodiversity monitoring site in these areas to monitor priority species and management issues that may affect local biodiversity.
Based on the classification of Fernando and colleagues (2008), this part of Mt Melibengoy mostly consists of the lower montane forest from 1000–1500 masl. Common native trees include those under the families Euphorbiaceae (Macaranga spp., Homalanthus spp., Aleurites sp.), Moraceae (Ficus spp.), Araliaceae (Polyscias spp., Schefflera spp., Heptapleurum spp.), Myrtaceae (Syzygium spp.), Phyllantaceae (Bischofia javanica), Dipterocarpaceae (Shorea spp.), Lauraceae (Cinnamomum spp.), Melastomaceae (Medinella spp., Melastoma spp.), and Meliaceae (Toona calantas).
Field Sampling
Fieldwork was conducted between September 2020 and August 2022. Opportunistic sampling was done to maximize the species richness data for birds in Mt Melibengoy. The survey was done along the 2-km transect laid along both trails, where 3–4 observers recorded all bird species along the transect and stopping at every 250 m for about 30 min for more thorough observations. A total of 420 person-hours were spent on field surveys, most of which happened during
the early morning (0700-0900H) and late afternoon (1400- 1600H). Birds were recorded using binoculars, digital camera with a 150–600 mm lens, and ‘playback’ of sound recordings.
Species were mainly identified by morphology using available photo-identification guides (Kennedy et al. 2000;
Allen 2020) and/or through calls compared with publicly available bird call recordings at xeno-canto.org. Our firsthand records of birds were augmented by reports from independent birding visits conducted by FJ and PMS around Mt Melibengoy, both inside and outside the boundaries of AVPL (location outside the AVPL is undisclosed to limit access). Bird records from Mt Melibengoy and Lake Holon published at ebird.org were also checked for verification.
The taxonomy and nomenclature follow the Checklist of Birds of the Philippines (WBCP), which is based on the International Ornithologists’ Union World Bird List 12.1 (Brinkman et al. 2022), except that we recognized herein the Tboli sunbird (Aethopyga tbolii) as a full species as it is by other authorities (Cheke et al. 2020; Allen 2020; Clements et al. 2022). Mindanao endemic are those species occurring on Mindanao and smaller adjacent islands of Basilan, Siargao, and Dinagat. The threatened status follows the International Union for Conservation of Nature Red List of Threatened Species (IUCN 2022) and the Philippine Red List (Gonzalez et al. 2018; DENR 2019). The trophic niche for each species was taken from the AVONET dataset (Tobias et al. 2022) and the population trend data was from the IUCN (IUCN 2022).
Results and Discussion
Species Richness and Composition
A total of 130 avian species from 49 families and 104 genera were recorded from Mt Melibengoy, which represents ca. 17.9% of all recognized avian species in the Philippines (Table 1). The most represented families are Columbidae (9.2%), Muscicapidae (7.7%), Accipitridae (6.9%), Dicaeidae
Table 1. List of avian species recorded in Mt Melibengoy, Tboli, South Cotabato, their endemism, and threatened status. R= Resident; M=
Migrant; E= Endemic; E-Min= Mindanao endemic; NE= Near Endemic; LC= Least Concern; NT= Near Threatened; VU= Vulnerable; E=
Endangered; OTS= Other Threatened Species; and OWS = Other Wildlife Species. DENR is the Philippine Red List.
No Species Name Common Name Status IUCN DENR
Megapodiidae
1 Megapodius cumingii Philippine Scrubfowl R LC VU
Phasianidae
2 Gallus gallus Red Junglefowl R LC OWS
Caprimulgidae
3 Lyncornis macrotis Great Eared Nightjar R LC OWS
Podargidae
4 Batrachostomus septimus Philippine Frogmouth E LC OWS
Hemiprocnidae
5 Hemiprocne comata Whiskered Treeswift R LC OWS
Apodidae
6 Aerodramus mearnsi Philippine Swiftlet E LC OWS
7 Apus pacificus Pacific Swift R LC OWS
8 Collocalia isonota Philippine Glossy Swiftlet E LC OWS
9 Hirundapus celebensis Purple Needletail R LC OWS
10 Mearnsia picina Philippine Spinetail E NT VU
Cuculidae
11 Cacomantis merulinus Plaintive Cuckoo R LC OWS
12 Cacomantis sepulcralis Rusty-breasted Cuckoo R LC OWS
13 Centropus viridis Philippine Coucal E LC OWS
14 Eudynamys scolopaceus Western Koel R LC OWS
15 Hierococcyx pectoralis Philippine Hawk-Cuckoo E LC OWS
16 Surniculus velutinus Philippine Drongo-Cuckoo E LC OWS
Columbidae
17 Chalcophaps indica Grey-capped Emerald Dove R LC OWS
18 Columba livia Rock Dove I LC OWS
19 Columba vitiensis Metallic Pigeon R LC OWS
20 Ducula poliochephala Pink-bellied Imperial Pigeon E NT CR
21 Geopelia striata Zebra Dove R LC OWS
22 Macropygia tenuirostris Philippine Cuckoo-Dove NE LC OWS
23 Phapitreron amethystinus Amethyst Brown Dove E LC CR
24 Phapitreron leucotis White-eared Brown Dove E LC OWS
25 Ptilinopus leclancheri Black-chinned Fruit Dove NE LC OWS
26 Ptilinopus occipitalis Yellow-breasted Fruit Dove E LC OWS
27 Spilopelia chinensis Eastern Spotted Dove R LC OWS
28 Streptopelia tranquebarica Red Turtle-dove R LC OWS
Rallidae
29 Amaurornis olivacea Philippine Bush-hen E LC OWS
30 Amaurornis phoenicurus White-breasted Waterhen R LC OWS
31 Hypotaenidia philippensis Buff-banded Rail R LC OWS
32 Zapornia fusca Ruddy-breasted Crake R LC OWS
Pandionidae
33 Pandion haliaetus Western Osprey R/M LC OWS
Accipitridae
34 Accipiter trivirgatus Crested Goshawk R LC OWS
35 Butastur indicus Grey-faced Buzzard M LC OWS
36 Haliaeetus leucogaster White-bellied Sea Eagle R LC OWS
37 Haliastur indus Brahminy Kite R LC OWS
38 Nisaetus pinskeri South Philippine Hawk-Eagle E EN EN
39 Lophotriorchis kienerii Rufous-bellied Eagle R NT OWS
40 Pernis ptilorhynchus Oriental Honey Buzzard R/M LC OWS
41 Pernis steerei Philippine Honey Buzzard E LC OWS
42 Spilornis holospilus Philippine Serpent Eagle E LC OWS
Strigidae
43 Otus gurneyi Giant Scops-owl E VU EN
44 Otus everetti Mindanao Lowland Scops-owl E LC OWS
Trogonidae
45 Harpactes ardens Philippine Trogon E LC OWS
Bucerotidae
46 Penelopides affinis Mindanao Hornbill E-Min LC EN
47 Rhabdotorrhinus leucocephalus Writhed Hornbill E-Min NT VU
Alcedinidae
48 Actenoides hombroni Blue-capped Kingfisher E-Min VU VU
49 Ceyx argentatus Southern Silvery Kingfisher E-Min NT VU
50 Halcyon gularis White-throated Kingfisher R LC OWS
51 Todiramphus chloris Collared Kingfisher R LC OWS
Meropidae
52 Merops americanus Rufous-crowned Bee-eater R LC OWS
Picidae
53 Chrysocolaptes lucidus Buff-spotted Flameback E LC OWS
54 Dryocopus javensis White-bellied Woodpecker R LC OWS
55 Yungipicus maculatus Philippine Pygmy Woodpecker E LC OWS
Megalaimidae
56 Psilopogon haemacephalus Coppersmith Barbet R LC OWS
Falconidae
57 Falco peregrinus Peregrine Falcon R/M LC OWS
58 Microhierax erythrogenys Philippine Falconet E LC OWS
Psittaculidae
59 Bolbopsittacus lunulatus Guaiabero E LC OWS
60 Loriculus philippensis Philippine Hanging Parrot/Colasisi E LC CR
61 Prioniturus waterstradti Mindanao Racquet-tail E-Min NT VU
Philippine Journal of Systematic Biology Online ISSN: 2508-0342
62 Saudareos johnstoniae Mindanao Lorikeet E-Min NT VU
Artamidae
63 Artamus leucorhynchus White-breasted Woodswallow R LC OWS
Campephagidae
64 Malindangia mcgregori McGregor's Cuckooshrike E-Min LC VU
65 Pericrocotus speciosus Scarlet Minivet R LC OWS
Pachycephalidae
66 Pachycephala philippinensis Yellow-bellied Whistler E LC OWS
Laniidae
67 Lanius cristatus Brown Shrike M LC OWS
68 Lanius schach Long-tailed Shrike R LC OWS
Dicruridae
69 Dicrurus hottentottus Hair-crested Drongo R LC OWS
Rhipiduridae
70 Rhipidura nigrocinnamomea Black-and-cinnamon Fantail E-Min LC OWS
Monarchidae
71 Hypothymis azurea Black-naped Monarch R LC OWS
Corvidae
72 Corvus macrorhynchos Large-billed Crow R LC OWS
Stenostiridae
73 Culicicapa helianthea Citrine Canary-flycatcher R LC OWS
Paridae
74 Pardaliparus elegans Elegant Tit E LC OWS
Pycnonotidae
75 Hypsipetes philippinus Philippine Bulbul E LC OWS
76 Pycnonotus goiavier Yellow-vented Bulbul R LC OWS
Hirundinidae
77 Hirundo rustica Barn Swallow M LC OWS
78 Hirundo tahitica House Swallow R LC OWS
Cettidae
79 Phyllergates heterolaemus Rufous-headed Tailorbird E-Min LC OWS
Phylloscopidae
80 Phylloscopus borealis Arctic Warbler M LC OWS
81 Phylloscopus olivaceus Philippine Leaf Warbler E LC OWS
82 Phylloscopus nigrorum Philippine Mountain Warbler E LC OWS
Locustellidae
83 Cincloramphus timoriensis Tawny Grassbird R LC OWS
84 Locustella caudata Long-tailed Grasshopper-warbler E LC OWS
85 Megalurus palustris Striated Grassbird R LC OWS
Cisticolidae
86 Orthotomus frontalis Rufous-fronted Tailorbird E LC OWS
Zosteropidae
87 Dasycrotapha plateni Mindanao Pygmy Babbler E-Min NT OTS
88 Zosterops everetti Everett's White-eye NE LC OWS
89 Zosterops japonicus Mountain White-eye R LC OWS
Timaliidae
90 Macronus striaticeps Brown Tit-Babbler E LC OWS
91 Micromacronus sordidus Mindanao Miniature Babbler E-Min NT OTS
Pellorneidae
92 Ptilocichla mindanensis Striated Wren-Babbler E LC OWS
Irenidae
93 Irena cyanogastra Philippine Fairy-bluebird E NT OWS
Sittidae
94 Sitta oenochlamys Sulphur-billed Nuthatch E LC OWS
Sturnidae
95 Aplonis minor Short-tailed Starling R LC OWS
96 Rhabdornis inornatus Stripe-breasted Rhabdornis E LC OWS
97 Rhabdornis mystacalis Stripe-headed Rhabdornis E LC OWS
98 Sarcops calvus Coleto NE LC OWS
Turdidae
99 Turdus obscurus Eyebrowed Thrush M LC OWS
(6.9%), and Cuculidae (4.6%). There are 68 species considered Philippine endemic, of which 19 species are found only on Mindanao. The remaining species are resident (n=53), migrant (n=7), and introduced (n=2). This estimate will likely increase with more surveys in other portions of Mt Melibengoy, especially in areas that are relatively less impacted by unregulated tourism and road developments. A recent bird survey in the neighboring BMR recorded 36 bird species not found in the present list, bringing the total of 165 bird species currently recorded for the KBA 196 and adjacent lowland forests (Senarillos et al. 2021; this paper).
The population of the Philippine mountain warbler (Phylloscopus nigrorum) in Mt Melibengoy is considered aberrant for having features different from other populations across its range (Fig. 2). This population exhibits a greenish- grey body with eye-rings of various sizes, which are much different from the usual shades of olive-green upperparts and yellow underparts with no eye-rings (see Kennedy et al. 2000;
Allen, 2020). Thus, Allen (2020) identifies the population in Mt Melibengoy (and the whole of KBA 196) as an undescribed race. Based on personal observations, there are also other bird species in Mt Melibengoy that warrant further taxonomic and
natural history work (e.g., Hypsipetes philippinus, Locustella caudata, Malindangia mcgregori). Several widespread polytypic bird species in the Philippines may be eventually subdivided into evolutionarily distinct and range-restricted species with integrative taxonomic work (Hosner et al. 2018).
Thus, future survey efforts should focus on less explored mountains like the KBA 196 to gather multiple types of data for a well-informed, scientifically robust avian taxonomy and systematics.
Mt Melibengoy is home to A. tbolii, known only from the high-elevation forests (> 1,000 masl) of the KBA 196 and nearby Mt Matutum (Allen 2020). The species was first described as a subspecies of A. boltoni collected from the nearby Mt Busa in 1993 (Kennedy et al. 1997) and was later proven to be a genetically distinct species deserving full species recognition (Hosner et al. 2013). It is relatively common within its range and less likely to become threatened in the next several years (KMEP and AJLS, pers. obs.). We recommend further work on its natural history and ecology to better understand this range-restricted species.
The Mindanao island-endemic and apparently rare Mindanao lorikeet (S. johnstoniae) is commonly observed
100 Turdus poliocephalus Island Thrush R LC OWS
Muscicapidae
101 Brachypteryx montana White-browed Shortwing R LC OWS
102 Copsychus mindanensis Philippine Magpie-Robin E LC OWS
103 Eumyias panayensis Turquoise Flycatcher R LC OWS
104 Ficedula crypta Cryptic Flycatcher E-Min LC OWS
105 Ficedula luzoniensis Thicket Flycatcher E LC OWS
106 Ficedula westermanni Little Pied Flycatcher R LC OWS
107 Leonardina woodi Bagobo Babbler E-Min LC OWS
108 Monticola solitarius Blue Rock Thrush R/M LC OWS
109 Muscicapa griseisticta Grey-streaked Flycatcher M LC OWS
110 Saxicola caprata Pied Bush Chat R LC OWS
Dicaeidae
111 Dicaeum australe Red-keeled Flowerpecker E LC OWS
112 Dicaeum bicolor Bicolored Flowerpecker E LC OWS
113 Dicaeum hypoleucum Buzzing Flowerpecker E LC OWS
114 Dicaeum ignipectus Fire-throated Flowerpecker R LC OWS
115 Dicaeum kampalili Flame-crowned Flowerpecker E-Min LC OTS
116 Dicaeum nigrilore Olive-capped Flowerpecker E-Min LC OWS
117 Dicaeum proprium Whiskered Flowerpecker E-Min LC VU
118 Dicaeum pygmaeum Pygmy Flowerpecker E LC OWS
119 Dicaeum trigonostigma Orange-bellied Flowerpecker R LC OWS
Nectariniidae
120 Aethopyga tibolii Tboli Sunbird E-Min NE OWS
121 Aethopyga pulcherrima Mindanao Sunbird E LC OWS
122 Anthreptes malacensis Brown-throated Sunbird R LC OWS
123 Arachnothera clarae Naked-faced Spiderhunter E LC OWS
124 Leptocoma sperata Purple-throated Sunbird E LC OWS
Passeridae
125 Hypocryptadius cinnamomeus Cinnamon Ibon E-Min LC OWS
126 Passer montanus Eurasian Tree Sparrow I LC OWS
Estrildidae
127 Erythrura coloria Red-eared Parrotfinch E-Min NT OTS
128 Lonchura atricapilla Chestnut Munia R LC OWS
129 Lonchura leucogastra White-bellied Munia R LC OWS
Motacillidae
130 Motacilla cinerea Grey Wagtail M LC OWS
Philippine Journal of Systematic Biology Online ISSN: 2508-0342
Figure 2. Various individuals of the Philippine mountain warbler (Phylloscopus nigrorum) showing the morphological differences of the Tboli population (A-D) from other individuals across its range: mountains in Davao de Oro (E-G), Central Panay Mountain Range, southern Antique (H), and Mt Polis, Luzon (I). Photos by Forest Jarvis (B, C, E, H), Peter Simpson (A, D, F, I), and Adrian Constantino (F).
Figure 3. The rare Mindanao lorikeet (Saudareous johnstoniae) is locally common in Mt Melibengoy, which is among the few montane sites in Mindanao where the species can be reliably found: A. old-growth montane forest of Mt Melibengoy outside the Protected Area that is needing immediate protection; B and C. Individuals of S. johnstoniae photographed outside the protected portions of the mountain. Photos by Forest Jarvis.
in Mt Melibengoy and has been a guaranteed sighting in the area among birders (Fig. 3). This species has a localized and patchy distribution in Mindanao, restricted only to mostly primary montane forests (Allen 2020). However, it has become extremely elusive and appears to be nearly or entirely extirpated from most mountains across its range, including Mt Kitanglad and Mt Apo (FJ & PMS, pers. obs.). There have also been no recent records of S. johnstoniae in the nearby BMR (Senarillos et al. 2021; KMEP & AJLS, pers. obs.) and Mt Matutum (list from ebird.org). Aside from habitat degradation, hunting and trapping for wildlife trade most likely contributed to the rarity and apparent absence of this species across its range (see Cruz & Lagunzad 2021), although this needs further investigation. This species appears to be more threatened than its current threatened status (NT for IUCN and VU for DENR) and should be appropriately assessed in the near future. It is currently listed under Appendix II of the Convention on International Trade of Endangered Species, which are species not necessarily threatened but trade must be controlled to ensure their survival.
Despite having suitable habitats for Philippine eagles (Pithecophaga jefferyi) (Sutton et al. 2023, 2024), there have been no recent sightings of this raptor within the area.
Gonzales (1971) recounted that the species is reported from Mt Melibengoy sometime in the 1960s. There is a high possibility that this critically endangered raptor still exists in the area considering the large tracts of relatively unexplored forests of this mountain, including those of Malibato mountain range, as well as the many historical sightings of the species in nearby Mts Matutum and Three Kings (Collar et al. 1999) and recently in the Busa mountain range (Senarillos et al. 2021).
While no recent evidence yet of this species’ presence, it is equally important to invest protecting the primary forests of Mt Melibengoy since adult P. jefferyi spends 75–80% of space and time outside of core nesting areas to forage (Sutton et al.
2024). The old-growth forests of KBA 196 are considered a priority site for protection and a stronghold of Philippine eagle populations in southern Mindanao, which should be further surveyed to determine accurate estimates of their population and develop targeted interventions for the survival of the species (Senarillos et al. 2021; Sutton et al. 2023, 2024).
The avian community in Mt Melibengoy exhibits diverse functional groups, with eight specialist trophic niches identified based on our list. Invertivores consist of almost half of all the species recorded (n=63; Fig. 4a), which is generally the most common foraging niche among birds (Pigot et al. 2020). This figure suggests that the avian community of Mt Melibengoy is mainly secondary or tertiary consumers (57.7%). Primary consumers consist of 20% of avian species recorded, and the remaining 22.3% are omnivores. Based on species richness alone, the distribution of these functional groups reinforces the ecosystem services birds provide to the mountain, such as pest control for both vertivores and invertivores and the enhancement of forest cover for frugivores (Whelan et al.
2016). High-resolution data that includes relative abundance and population estimates will be helpful in supporting this hypothesis further.
Of the species recorded, three are identified under the IUCN Red List and 19 species under the Philippine Red List (PRL). The most threatened bird recorded is the South Philippine hawk-eagle (Nisaetus pinskeri), classified
Figure 4. Published (A) Trophic niches and (B) population trends of avian species found in Mt Melibengoy. The former was taken from the AVONET dataset and the latter from the IUCN.
as Endangered under both the IUCN and PRL. This large raptor species resides mostly in lowland forests up to 1900 masl and is thus vulnerable to habitat degradation (Collar et al. 1999; Allen 2020). It is regularly recorded in the BMR, and most likely the whole of KBA 196, and possibly uses its forests as its breeding ground (Senarillos et al. 2021). A recent assessment of global raptor ranks N. pinskeri as among the highest priority raptor species for research and conservation (Buechley et al. 2019), highlighting the need to further study its ecology to inform species conservation plans.
With 53.1% of the avian species in Mt Melibengoy having decreasing population trends (Fig. 4b), a monitoring mechanism for birds using our list as baseline should be established to track long-term changes of their communities amidst the impacts of habitat changes and climate change.
Studies aimed at understanding the differences in avian species composition and diversity among habitat types, disturbance levels, and management regimes are recommended to better understand species’ responses to localized environmental changes.
Threats to Avian Community in Mt Melibengoy
The avian community of Mt Melibengoy is faced with several threats even inside the protected area, including forest clearing (e.g., shifting agriculture, charcoal production, human settlements expansion), road development, unregulated and unabated tourism, alien invasive species, and wildlife poaching. Agricultural crops, banana plantations, and several patches of the highly invasive Piper aduncum are found at the lower elevations (about 1000 masl) of the survey site.
Philippine Journal of Systematic Biology Online ISSN: 2508-0342 Previous studies in the Philippines show that these modified habitats support less bird diversity and endemism compared to primary forest areas (Mallari et al. 2011; Tanalgo et al. 2015, 2019), thus maintaining the original forest cover is still key to maintaining local avian diversity. In addition, selective clearing of primary-forest trees for abaca (a species of fiber crop) occurs even deep within the forest interior. Although its effects on birds are not yet fully understood, this activity is still requiring management attention from both the DENR and local government units.
Both the Kule and Nabul trails are the primary entry points to Lake Holon, and thus disturbances brought by human presence and noise are most intense in these areas.
Determining the impacts of tourism on avian fauna at this tourism and birding hotspot is a recommended topic for further research, as there has been some evidence of the negative impacts of recreation on montane birds (see Hochreutener et al. 2022). Although tourism is mainly concentrated at the survey sites, the development of a concrete road that cut across the once-contiguous forests of Mt Melibengoy and Malibato Mountain Range (see Fig. 1) has enabled the proliferation of tourism activities on the northeastern slope of the mountain, which is free from the more stringent regulations imposed inside the protected area.
Several studies have shown how road infrastructure developments negatively affect biodiversity (Benítez-López et al. 2010; Bennett 2017). Although we acknowledge that road developments are necessary to facilitate economic development, its impacts on local biodiversity must not be overlooked. The easy accessibility provided by roads would eventually facilitate human and agricultural encroachment (Sloan et al. 2019) and possibly include the spread of alien invasive species. We particularly highlight the presence of domesticated cats (Felis catus) and potentially non-native rats (Rattus sp.) at the campsite of Lake Holon, which are considered drivers of avian extinctions and remain a major threat to the avian communities (Lees et al. 2022). Their presence should be closely monitored and controlled to avoid local extinctions of native fauna in the area.
Albeit not as large in scale as other threats, poaching of birds has also been recorded in villages around Mt Melibengoy. The locally threatened Philippine hanging parrot (L. philippensis) was the most poached birds in nearby villages (KMEP & AJLS, pers. obs.), although S. johnstoniae may also be a target species for pet trade.
Conservation Implications
The KBA 196 in which Mt Melibengoy is situated is among the many cases of coverage mismatch between KBAs and Philippine protected areas under NIPAS (Mallari et al. 2016). Only 274.2 km2 or 23.6% of KBA 196 is currently protected under national law, leaving other portions unprotected and vulnerable to habitat modifications. Since a watershed approach was used to delineate the boundaries of AVPL, only those slopes of the BMR and Mt Melibengoy that contribute water to the Allah River are included in the protected area. However, calls to establish a legal framework for protection on the unprotected portions of the KBA 196 have been put forward through empirical field biodiversity studies (Pitogo et al. 2021; Saavedra & Pitogo 2021; Senarillos et al. 2021). The results of these studies are instrumental for
the ongoing legislation process to include the southern slope of the BMR into the NIPAS.
Although our results are preliminary, they echo similar calls to afford the unprotected portions of Mt Melibengoy some legal framework for protection to conserve and preserve its biodiversity. The municipal local government unit (MLGU) of Tboli declared 5,000 ha of Mt Melibengoy a conservation and ecotourism area under Municipal Ordinance No. 58 Series of 2008 but the boundaries have not been delineated as of writing and there are no clear mechanisms yet for protecting the forests and its biodiversity outside the protected area. A holistic conservation approach for Melibengoy forests would be imperative to maintain its rich, vulnerable, and somehow unique avian community. Thus, providing the unprotected forests of Mt Melibengoy some form of legal protection should be the utmost priority of the MLGU Tboli and DENR in close cooperation with the indigenous peoples and local communities.
Considering the presence of many bird species important for science (e.g., P. nigrorum, A. tbolii) and conservation (e.g., S. johnstoniae, N. pinskeri) and having forested areas suitable for the Philippine eagles, we call on for the immediate declaration of Mt Melibengoy’s unprotected forests (including the neighboring Malibato Mountain Range) as a Critical Habitat (CH) for wildlife, especially of S. johnstoniae, which is rare across its range but its presence is already established in Mt Melibengoy. CHs are designations for habitats of threatened species that are outside protected areas under NIPAS (DENR 2007). Mt Melibengoy and the neighboring Malibato forest host several threatened and endemic bird species, faced by several management issues mentioned herein, and is a priority area for conservation—all are major considerations for CH designation (see DENR 2007).
The establishment of CH will afford the Melibengoy- Malibato mountain complex a management plan and resources for its immediate protection until such time these are declared Protected Areas under NIPAS, which normally takes longer due to its more stringent process (see DENR 2017). Other effective area-based conservation measures, such as CH, are considered to functionally complement Protected Areas and other existing conservation initiatives (Gurney et al. 2021).
For the protected forest of Mt Melibengoy under NIPAS, we recommend including all but the tourism area (trails and campsite) within the Strict Protection Zone of AVPL for tighter regulation on the use of the natural resources therein, which only allows traditional practices of indigenous peoples and scientific research.
Although our results are limited only to the species list, this paper still provides the much-needed evidence to justify the immediate protection of the unprotected forests of Mt Melibengoy and strengthen its already existing management mechanisms. Empirical species data is straightforward and thus an easy science to communicate with policymakers and other stakeholders to secure their support for conservation endeavors, such as the establishment of CHs. Moreover, the species list is among the primary and most important evidence needed to establishing area-based protection measures in the Philippines mainly aimed at biodiversity conservation, such as PA and CH (DENR 2007, 2017).
In this paper, we present Mt Melibengoy as an important area for avian research and conservation, and we encourage
researchers to build on this list and explore the patterns and processes influencing avian communities for the evidence- based conservation and management of this partially protected KBA. We emphasize the important role of citizen scientists in this process by providing publicly accessible data, such as those published at eBird, to complement targeted ornithological surveys. This collaborative approach to generating the science needed to inform policies and actions is necessary for a more engaging, inclusive, and accessible process of biodiversity conservation in the Philippines.
Acknowledgements
Fieldwork from 2020–2022 was conducted during the implementation of the Biodiversity Monitoring System in the Allah Valley Protected Landscape. The Protected Area Management Board approved Resolution No. 35 Series of 2021, further supporting biodiversity inventory to inform conservation and management interventions in AVPL. We are grateful to the Protected Area Superintendent Leonisa C.
Alfaro for her active and continued support, the Municipal Local Government Unit of Tboli for allowing us to do fieldwork in the area, our local guides for accompanying us during fieldwork, and to the bird photographers and enthusiasts who have made their records publicly available at ebird.org.
We also thank the two anonymous reviewers for their help in improving this manuscript.
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