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Sylvatrop, The Technical Journal of Philippine Ecosystems and Natural Resources 13(1&2): 63-80
Preliminary report on the amphibians and
reptiles of Balbalasang-Balbalan National
Park, Luzon Island, Philippines
Arvin C. Diesmos1,4, Rafe M. Brown2,4, and Genevieve V. A. Gee3,4
1National Museum of the Philippines, Padre Burgos Avenue, Ermita 1000, Manila,
Philippines; Current address: Department of Biological Sciences, National University
of Singapore, Block S3 14 Science Drive 4, Singapore 117543
E-mail: kaloula@i-manila.com.ph
2 Section of Integrative Biology, University of Texas, Austin Texas, 78712
Current address: Museum of Vertebrate Zoology, 3101 Valley Life Science Building
University of California, Berkeley, CA 94720
E-mail: rafe@mail.utexas.edu
3 Haribon Foundation for the Conservation of Natural Resources
4 Flr. Fil Garcia Tower, 140 Kalayaan Avenue, Diliman 1101, Quezon City, Philippines
E-mail: jutisha@yahoo.com
4Wildlife Conservation Society of the Philippines
Room 106 Institute of Biology, University of the Philippines
Diliman 1101, Quezon City, Philippines
We provide information on the amphibians and reptiles of Balbalasang-
Balbalan National Park (BBNP) based on field surveys we conducted on several
localities in 1998, 1999, 2000, 2001, and 2003. We recorded a total of 51
species of amphibians and reptiles from the area. Baseline data on species
richness, habitat and altitudinal distribution, and natural history are presented.
The herpetofauna exhibited high levels of endemicity and included at least 13
species that are potentially new to science (nine frogs of the genus Platymantis,
three scincoid lizards of the genus Sphenomorphus, and one snake). We suspected
that additional species await discovery after more thorough inventories have
been completed especially targeting the low elevation forests of these vast
mountain ranges. Apart from these exciting new discoveries, another significant
outcome of our survey work is the rediscovery of five “lost species” from the
Cordillera Central mountain range including Platymantis cornuta, Rana igorota,
and Sphenomorphus luzonensis, all of which have been considered previously
Keywords: Central Cordillera Mountains, amphibians, reptiles, new species, rediscovery, Platymantis,
Rana igorota, biodiversity, conservation, Philippines
64 A.C. Diesmos et al.
as either rare or in the verge of extinction. Our data suggest that these species
are fairly common within the national park. We provide accounts for these
species and point out possible new areas of biological studies. The high species
richness and endemism of the herpetofauna of BBNP is an indication of the
overall excellent condition of its forests.
EDWARD H. TAYLOR WAS THE FIRST HERPETOLOGIST TO EXPLORE THE RUGGED HIGHLANDS OF THE CORDILLERA
Central mountain range in north central Luzon Island, Philippines. His relatively brief
collecting sorties took him to several areas of this vast mountain range (Taylor 1922a).
Taylor described nine new species of frogs, lizards, and a snake from various mountain
localities in the Cordilleras, all of which appeared, at that time, to be unique to this
region (Taylor 1922a, 1922b, 1922c, 1925, 1963).
Few field collections of the herpetofauna from the Cordilleras took place after
Taylor’s work, save for a brief visit by members of the Philippine Zoological Expedition
of the Chicago Natural History Museum (predecessor to Field Museum of Natural
History), right after the Second World War (Inger 1954). More recently, herpetologists
from the United States National Museum of Natural History surveyed the herpetofauna
in several localities around the Cordilleras, in the late 1980s. Most of the results of this
effort, however, remain unpublished.
In July 1998, in collaboration with Angel Alcala (Silliman University), we undertook
a preliminary survey work on the herpetofauna of Balbalan, a region within the Cordilleras
that was first visited by Taylor nearly 80 years back. Our brief survey was part of a larger
effort to gain a better understanding of the diversity, ecology, and systematics of the
herpetofauna of Luzon Island, which we believe is unreasonably underestimated from
previous works (e.g. Inger 1954, Alcala 1986) and poorly studied (Brown et al. 1996,
Diesmos 1998, Brown et al. 2001, Brown and Diesmos 2001). Beginning in 2000,
biologists from the Haribon Foundation for the Conservation of Natural Resources and
the Field Museum of Natural History conducted a joint biological expedition to inventory
the biodiversity of Balbalasang-Balbalan National Park (BBNP) in Kalinga Province.
In this preliminary report, we present baseline information on the species diversity,
relative abundance, and ecology of the amphibians and reptiles of BBNP based on the
results of preliminary survey work undertaken in 1998 and 1999 and the systematic
inventories conducted in 2000, 2001, and 2003.
Materials and methods
Taxonomic identification of herpetological specimens from BBNP was facilitated
by direct comparison to specimens (including types whenever possible) housed at the
California Academy of Sciences (CAS), the Field Museum of Natural History (FMNH),
65
Amphibians and reptiles of Balbalasang-Balbalan National Park
National Museum of the Philippines (PNM), and the Texas Natural History Collection
(TNHC) at the Texas Memorial Museum, University of Texas, Austin.
Study area
The Cordillera Central is a vast and rugged mountain range that dominates the
skyline of the north central region of Luzon (see map in Heaney et al., this volume).
Over a dozen peaks within the mountain range rise to over 2,000 m while a few reach
nearly 3,000 m. There are numerous drainage systems and deep valleys that separate
mountain massifs. The climate is cool and of the temperate type. Rainfall seasonality in
the Cordilleras falls under two categories: Type I (dry from November to April and wet
during the rest of the year) affects the eastern parts of the range and Type III (with no
pronounced seasons) is prevalent on eastern regions. There are, at present, five national
parks and forest reserves within the Cordilleras. One such protected area is the BBNP,
located in the Municipality of Balbalan, Kalinga Province. It was declared as a national
park in 1974 by virtue of Proclamation No. 1357 and covers an area of about 17,838 ha.
The highest peak, Mt. Sapocoy, is at 2,456 m. BBNP was proposed for inclusion in the
National Integrated Protected Areas System (NIPAS) of the Philippine government
(Dickinson et al. 1991, Mallari et al. 2001, Ong et al. 2002).
Herpetofaunal inventories were conducted in 10 sites within BBNP, all located in
the Municipality of Balbalan, Kalinga Province. With the exception of three sites (i.e.,
Balbalan, Naldaan, and Longolong), we sampled the herpetofauna in the same localities
where inventories of birds and mammals were performed (see map and further descriptions
of the sampling sites in Heaney et al., this volume). Brief descriptions of our sampling
sites are summarized as follows:
1. Balbalan Municipality (750 m, coordinates not recorded; visited, 7-11 July
1998). The survey site was on a ridgetop above the town of Balbalan, in secondary
forest of the transition lowland-montane type. Only a few huge dipterocarp
trees remain and the cutting of trees was fairly evident. We heard chainsaws
operating in the area. We observed many decaying tree stumps, logs, and slabs.
The understorey is dense with tree saplings, screw pine (Pandanus), and rattan
palms.
2. Naldaan, Barangay Balbalasang (1,200 m, coordinates not recorded; 19-21
December 1999). Naldaan is located 10-15 km northwest of Barangay
Balbalasang. Pine forest dominate the vegetation in this area interspersed with
patches of lower montane forest with trees reaching to a height of over 35 m.
Surveys were conducted in such habitat and along the Naldaan River, a 5-7 m-
wide swift flowing, cool, and clear mountain stream.
3. Barangay Balbalasang (925 m, 17o 29.1'N 121o 03.3'E; 25-27 March 2000, 9-
11 March 2001, and 17-21 February 2003). We surveyed the herpetofauna in
66 A.C. Diesmos et al.
the vicinity of the town of Balbalasang, primarily in the agricultural lands
(cropland and pasture) in the narrow band of flat areas and low hillsides that
are adjacent to the Saltan River. The original vegetation was lower montane
forest with lowland rainforest elements but little evidence of the lowland forest
remains. Pine forest with either fire-maintained grassland or brushy second-
growth predominated on the adjacent hillsides.
4. Mapga (1,050 m, 17º 28.543'N 121º 04.354'E; 11-18 March 2001). This site
is adjacent to the Mapga River. Vegetation includes a small area of pine forest
on a steep hillside, fairly extensive second-growth and secondary forest on
fairly flat land that was first cleared at the time of World War II, and mature
lower montane rainforest on moderately to very steep slopes. We also surveyed
the herpetofauna from a permanent pond (about 500 m2 in area) located in a
flat area about 10 m above and 30 m away from the river.
5. Longolong (1,025 m, 17º 28.42'N 121º 04.19'E; 23-25 March 2001). The
habitat is a mixture of primary and mature secondary lower montane forest.
Some patches of forest (30-50 m2) on relatively flat ground have been cleared
for agriculture 10-15 years ago. Primary forest occurs on steep slopes and along
the Longolong creek.
6. Magdallao, lower (1,300 m, coordinates not recorded; 31 March-6 April 2000).
The forest in this area is of the lower montane forest type with canopy reaching
to a height of about 25 m. Surveys were conducted on ridge tops along and near
forest trails.
7. Magdallao, upper (1,600 m, 17o 27.5'N 121o 04.1'E; 28 March-6 April 2000).
This sampling area was in mature montane rainforest dominated by oaks that
reached a height of ca. 15 m, with a grove of pine trees several hundred meters
away. Several small streams and some relatively flat areas provided abundant
moist habitat.
8. Amlicao (1,800 m, 17o 25.95'N 121o 04.55'E; 18-27 March 2001). Our camp
was located along the mountain trail from Balbalasang to the town of Pasil, in
mature transitional montane-mossy rainforest dominated by oaks. We sampled
in areas from steep hillsides up to the top of the adjacent ridge where thickets
of bamboo were present. Moss was especially common along the upper portion
of the ridge.
9. Mt. Bali-it, lower (1,950 m, 17o 25.8'N 121o 00.1'E; 19-28 February 2003).
Surveys were conducted from 1,500 m to 1,950 m elevation. We worked along
and near existing trails, hill slopes and ridges, and in streams, at altitudes
between 1,500 m to the base camp (1,950 m) on Mt. Bali-it, covering lower
and upper montane forests and lower mossy forest.
10. Mt. Bali-it, upper (2,150 m, 17o 25.7'N 120o 59.8'E; 25 February-3 March
2003). Surveys were undertaken from an elevation of 1,950 m to 2,150 m.
We surveyed the herpetofauna on and near the peak of Mt. Bali-it, in lower
67
Amphibians and reptiles of Balbalasang-Balbalan National Park
mossy forest dominated by oaks with a canopy height of 6-8 m in lower or
protected spots, and as little as 3 m in high, exposed sites. Moss on the
ground and trees were common and ground orchids and ferns were abundant.
Sampling techniques
Field techniques included a combination of timed searches, microhabitat sampling,
and tape-recording of advertisement calls of male frogs (Heyer et al. 1994). Information
on type of habitat and microhabitat (e.g., tree holes, burrows, rotten logs, tree buttresses,
tree foliages, leaf litter, and isolated pools) where an individual of a species was observed
or caught, the elevational distribution, time of observation or capture, behavior of the
species before capture, and external morphological characters and measurements were
taken. Adult specimens were caught either with the aid of nets or solely by hand while
larvae (tadpoles) were collected from aquatic microhabitats through dip netting. We
worked in small groups (2-4 persons) and spent most of the day and night walking along
existing forest trails which served as our transect lines. We walked an average of 1.5 km
per sampling day and spent an average of 10 person-hours/day sampling the herpetofauna
from each site (typically from 0900 hr to 1200 hr, 1400-1600 hr, and 1900-2400 hr).
Only one transect line in each survey site was sampled. Surveys were conducted in both
day and night and in both wet and dry weather. Our sampling effort was generally
uniform in all survey sites including the built up areas and human-modified environments
in the Balbalasang village.
We assessed the relative abundance of each species based on the cumulative
number of encounters of individuals of a particular species during the whole duration of
the study. We qualitatively defined four abundance categories as “common” for species
that were encountered more than 50 times, “fairly common” for those that were
encountered 30-50 times, “uncommon” for those that were encountered 10-20 times,
and “rare” for species that were encountered less than 5 times. Temporal (diel) activity
of each species was also noted.
Specimens of each species encountered were collected as voucher materials
particularly those that we were not able to identify in the field (as per stipulated protocols
detailed in research permits) using standardized preservation techniques (Simmons 1987,
Heyer et al. 1994). Those that were readily identified in the field were later released at
the capture site. Representative tissue samples from each specimen were also taken.
Vouchers were initially fixed in 10% buffered formalin and were eventually stored in
70% ethyl alcohol. These specimens are presently deposited at FMNH. Representative
specimens of each species will be transferred to PNM at a later date.
Interviews with residents of Barangay Balbalasang and the Municipality of Balbalan
were conducted to supplement data gathered from our direct field observations. Only
68 A.C. Diesmos et al.
those interview accounts that were ascertained to be valid (i.e., based on available
literature and our personal knowledge of the species) are incorporated in this report.
Results and discussion
Species richness and composition
We recorded 51 species of amphibians and reptiles from BBNP comprised of 23
species of frogs, 16 lizards, 11 snakes, and one turtle (Table 1). Species endemicity is
remarkably high with as many as 26 species (50% of the fauna) restricted to Luzon
faunal region and up to 17 species (32%) possibly restricted to the mountains of the
Cordilleras (Inger 1954, Alcala 1986, Alcala and Brown 1998, Brown et al. 2001). At
least 30 herpetofaunal species are recorded from the Cordillera Central for the first
time. Data on the occurrence of each species and other pertinent information are
summarized in Table 1. We included in the list three snakes (Python reticulatus, Naja
philippinensis, and Ophiophagus hannah) and a turtle (Cuora amboinensis) based on
the strength of interview accounts with the local residents within BBNP.
Our inventories resulted in an astonishing discovery of 13 species that are highly
likely to be new to science: nine frogs of the genus Platymantis, three skinks of the
genus Sphenomorphus, and one snake (Table 1). Furthermore, our field surveys led to
the rediscovery of several species that were previously known only from type specimens
(ranging from one to half a dozen specimens) that were first collected by herpetologists
80-150 years ago (Taylor 1922a, 1922b, Brown and Alcala 1980, Brown et al. 2000a).
Our survey results only underscore the fact that the herpetofauna of Luzon is poorly
studied and that the diversity and endemism of this fauna was unreasonably
underestimated (see comments in Diesmos 1998, Brown et al. 2000a, Brown et al.
2001, Brown and Diesmos 2001, Diesmos et al. 2002).
Notes on biogeography
Although information on the herpetofauna of BBNP and the Central Cordilleras is
certainly far from complete, we venture a brief commentary on the biogeographic
significance of this fauna.
An estimated 14 of the 51 species recorded from BBNP (i.e., 10 species of
Platymantis, Rana igorota, two species of Sphenomorphus and a typhlopid snake; see
Table 1), particularly those that were only recorded from high-elevation forest sites,
may be restricted to the Cordilleras and perhaps, only to a few mountain peaks within
BBNP such as Mt. Amlicao and Mt. Bali-it. We based this assumption from the almost
recurrent pattern of discovery of endemic herpetofaunal species from high-elevation
mountains (e.g. Brown et al. 1995, Ferner et al. 1997, Alcala et al. 1998, Diesmos
69
Amphibians and reptiles of Balbalasang-Balbalan National Park
Table 1. Herpetofauna of BBNP (this species list and respective information are based on our own field studies). = Cordillera endemic, =
Luzon faunal region endemic, • •
• •
• = Philippine endemic, † = non-endemic (native species). Sites: 1 = Balbalan, 2 = Naldaan, 3 =
Balbalasang, 4 = Mapga, 5 = Longolong, 6 = Magdallao (lower), 7 = Magdallao (upper), 8 = Amlicao, 9 = Mt. Bali-it (lower), 10 = Mt.
Bali-it (upper). Habitat types: F= forest, R= riverine forest, E= edges and second growth, O= open and built-up areas. Relative
abundance: C = common, FC = fairly common, U = uncommon, R = rare, ND = no data. Diel activities: N = nocturnal, C =
crepuscular, D = diurnal. Distributional data based on Inger (1954), Alcala (1986), Alcala and Brown (1998). Conservation status
follows IUCN (2003, URL http://www.redlist.org/) and CITES (2003, URL http://www.cites.org/).
Species Sites Habitat Elevational Relative Diel Remarks
range (m) abundance
Ranidae
Limnonectes macrocephalus 1-5 R 750-1050 C N Collected for food
Occidozyga cf. laevis 1,3,5 O 750-1025 FC N Taxonomic studies needed
Platymantis cf. cornuta 1,2,4,5,6 F 750-1300 FC N Taxonomic studies needed
IUCN: Data Deficient
Platymantis pygmaea 1,3,5 F 750-1025 FC C Taxonomic studies needed
IUCN: Vulnerable
Platymantis sp. A 1,3,5 F 750-1050 C N Possible new species
Platymantis sp. B 1 F 750 U N Possible new species
Platymantis sp. C 3,5 F 1050 U C Possible new species
Platymantis sp. D 7,8 F 1600-1800 C D, C Possible new species
Platymantis sp. E 7-10 F 1600-2150 C N Possible new species
Platymantis sp. F 7-10 F 1600-2150 C N Possible new species
Platymantis sp. G 7-10 F 1600-2150 C N Possible new species
Platymantis sp. H 9,10 F 1880-2150 C N Possible new species
Platymantis sp. I 9,10 F 1500-1950 C N Possible new species
Platymantis sp. (cf. “rivularis”) 2-6 F 900-1600 FC N Taxonomic studies needed
Rana igorota 5 R 1025 U N Taxonomic studies needed
Rana luzonensis 2,3,6, R 900-1950 C N
7,8,9
Rana similis 1 R 750 R N
Rana (Fejervarya) vittigera 1,3 O 750-950 C N Collected for food
Microhylidae
Kaloula kalingensis 1-7 F, E 750-1600 C N
Kaloula rigida 1,3 E, O 750-925 U N
Ü
•
70 A.C. Diesmos et al.
Table 1. Cont.
Species Sites Habitat Elevational Relative Diel Remarks
range (m) abundance
Rhacophoridae
Philautus cf. surdus 1-7 F, E 750-1600 C N Taxonomic studies needed
Polypedates leucomystax 1,3,4 E, O 750-1050 C N
Rhacophorus cf. pardalis 1,4 F, E 750-1050 U N Taxonomic studies needed
Bataguridae
Cuora amboinensis 1,3 R Below 925 ND C Based on reports by locals;
CITES: Appendix II
Gekkonidae
Cosymbotus platyurus 1,3 O 750-950 C N
Gekko gecko 1,3 E, O 750-950 C N
Gehyra mutilata 1,3 E, O 750-950 C N
Lepidodactylus sp. 3 E, O 925 R N Taxonomic studies needed
Agamidae
Bronchocela sp. 3,4 F, E 900-1050 U D Taxonomic studies needed
Draco spilopterus 3 F, E 925 ND D Taxonomic studies needed
Scincidae
Mabuya cumingi 1,2,3,6 F, E 750-1200 C D Taxonomic studies needed
Mabuya multicarinata borealis 1-7 E, O 750-1600 C D Taxonomic studies needed
Sphenomorphus cf. abdictus 3,5 F, E 950-1050 U D Taxonomic studies needed
Sphenomorphus cf. luzonensis 4 F, E 1600 R D Taxonomic studies needed
Sphenomorphus sp. A 1 F 750 R D Taxonomic studies needed
Sphenomorphus sp. B 4,5,8 F 1300-1800 R D Taxonomic studies needed
Sphenomorphus sp. C 9 F 1950 R D Taxonomic studies needed
Brachymeles bicolor 6 F 1050 R D Taxonomic studies needed
Ü
•
Ü
Ü
Ü
Ü
Ü
•
•
•
•
71
Amphibians and reptiles of Balbalasang-Balbalan National Park
Table 1. Cont.
Species Sites Habitat Elevational Relative Diel Remarks
range (m) abundance
Brachymeles cf. bonitae 3 F, E 950 R D Taxonomic studies needed
Varanidae
Varanus salvator marmoratus 1,3 E, O Below 900 ND D Collected for food;
CITES: Appendix II
Pythonidae
Python reticulatus 1,3 E, O Below 950 ND D Based on reports by locals;
CITES: Appendix II
Typhlopidae
Ramphotyphlops braminus 3 E, O 95 0 FC N
Typhlopid sp.3 F, E 950 R ? Possible new species
Colubridae
Ahaetulla prasina 3 F, E 9 50 ND D, N Specimen not collected
Calamaria bitorques 3 F 900-1000 ND D
Cyclocorus lineatus 1 F 9 50 ND D, N
Dendrelaphis caudolineatus 3 F 950 ND D Specimen not collected
Oxyrhabdion leporinum 3 F 950 R C, N
Zaocys luzonensis Near 1 F, E About 700 ND D Specimen not collected
Naja philippinensis 1,3 E, O No data ND D, N Based on reports by locals;
CITES: Appendix II
Ophiophagus hannah 3 F, E No data ND D, N Based on reports by locals;
CITES: Appendix II
•
Ü
Ü
Ü
Ü
•
•
Ü
•
•
Ü
72 A.C. Diesmos et al.
1998, Brown et al. 1999). Our preliminary information from the herpetofauna of Mt.
Data, south of BBNP, also indicates that some of the species found in that area may be
closely related to those from BBNP.
On the other hand, 27 of the 51 species recorded are widely distributed on Luzon
with a few that are also found on other islands in the Philippines. These species essentially
constitute the low-elevation Philippine herpetofauna and are typically found in lowland
forest, but most can also thrive in human-controlled environments such as in secondary
growth vegetation, agricultural areas, and built up areas. It has been documented that
some herpetofaunal species in the Philippines [e.g., Rana (Fejervarya) vittigera, many
gekkonid lizards] have become established into new territories through human-aided
dispersion (Inger 1954, Alcala 1986).
Available data indicated that some degree of affinity exists among the herpetofauna
of BBNP, the Sierra Madres, and the Zambales Mountains. At least six Philippine
endemics are shared among these three mountain ranges. Kaloula kalingensis, Mabuya
cumingi, and Sphenomorphus abdictus are known from both the Sierra Madres and
Zambales Mountains while Platymantis pygmaea, K. rigida, and Brachymeles bicolor
have been found in the Sierra Madres but not in the Zambales (Brown et al. 2000a).
Noteworthy is the striking ecological variation and distribution exhibited by some species,
which might reflect taxonomic distinctiveness. For instance, K. rigida, which is restricted
to elevations above 700 m in the Cordilleras, has been found as low as 50 m in the
Sierra Madres (Alcala and Brown 1998). Another interesting example is exhibited by P.
pygmaea. This species was discovered from the Sierra Madres (Alcala et al. 1998) and is
known from Aurora Memorial Park (Brown et al. 2000a), BBNP, and more recently, was
found on Sibuyan Island (unpublished data). Surprisingly, P. pygmaea has not been
found on mountain localities in between the Sierra Madres and Sibuyan despite intensive
field surveys (Ross and Gonzales 1992, Diesmos 1998, Brown et al. 2002a, Diesmos et
al. unpublished data), representing an intriguing disjunct distribution.
A great deal of work is needed to bridge the large gap of information pertaining to
geographic distribution, phylogenetic relationships, and systematics of many Philippine
species. Only when such issues have been addressed fully can the biogeography of the
herpetofauna of the Central Cordilleras, and ultimately, that of Luzon can be fully
understood.
Ecology and natural history
Our data show that majority (75%) of the herpetofauna of BBNP are forest-restricted
species while the rest of the species are found in non-forested and disturbed habitats. In
agricultural plantations, built up areas, and other man-modified environments, only a
few tolerant species can be found [e.g., Rana (Fejervarya) vittigera, Occidozyga cf.
73
Amphibians and reptiles of Balbalasang-Balbalan National Park
laevis, Polypedates leucomystax, Gekko gecko, and Dendrelaphis caudolineatus]. In
and around disturbed forest and rivers, several more species can be found. However, in
deep forest, we found 39 species of frogs, lizards, and snakes that we never encountered
in open and disturbed habitats. These include most of the undescribed species of frogs,
lizards, and snakes. In particular, Rana igorota warrants comment because this is a
streamside frog that we never observed even in the cleanest of forested streams and
rivers if any disturbance is present. We only encountered this frog in small mountain
streams that were virtually undisturbed by human as judged by the presence of large
males of the fanged frog L. macrocephalus in the same streams. The latter species is an
excellent indicator of the presence of local hunting pressures. If any human predation
on this species is present, the largest of the males are invariably absent as these are
prized by gatherers. Only in streams that are rarely visited by hunters do we ever find
large males in excess of 150-350 g with lengths of nearly 200 mm (Brown et al. 1996,
2000a). Because very large male fanged frogs were present in Longolong (Site 5) and
were never found in rivers and streams from other sites, we assumed that hunters seldom
visited this isolated area. In fact, the streams in this site are not tributaries of the larger
Mapga River and we surmised that this is the reason for the absence of disturbance by
hunters who usually follow waterways when hunting for frogs. The fact that R. igorota
only occurs in the most isolated and relatively undisturbed mountain streams suggests
that this species has little or no tolerance for human-caused disturbance and thus, may
serve as an excellent “indicator species” for ecosystem health in the Cordilleras.
The distribution pattern of the herpetofauna of BBNP is positively related to
elevation and the coinciding gradients of temperature and humidity. At lower elevations,
forests are hotter and drier and support higher levels of reptile diversity and abundance
in most species. At higher elevations, reptiles are scarcer and, when encountered, species
are less abundant with fewer individuals encountered. Species richness was generally
highest at lower elevations. At this elevation, most species of frogs were congregated
around streams and rivers (L. macrocephalus, R. luzonensis, and R. igorota) or stationary
pools of water (R. pardalis, P. leucomystax, O. cf. laevis). Interestingly, the diversity of
certain groups of frogs increased with increasing elevation particularly at the montane
forest (Table 1). This distribution pattern was particularly evident in frogs of the genus
Platymantis and Philautus, which is similar to that exhibited by murid rodents (Rickart
et al. 1991, Heaney 2001). The reason for this may be simple. The reproductive mode of
these frogs is of the terrestrial development type (Alcala 1962; Alcala and Brown 1982,
1998). Being direct developers, these frogs do not require streams or standing water to
reproduce, thus, enabling them to successfully thrive in montane and mossy forests,
which are otherwise uninhabitable to many other groups of frogs (Duellman and Trueb
1994).
Several life history patterns of individual species deserve comment because they
are rare or unique among Philippine amphibians and reptiles. For example, one of the
74 A.C. Diesmos et al.
new species of Platymantis that we discovered calls only during the day (Platymantis
sp. D). This is atypical for Philippine frogs of the genus Platymantis and could be the
first example of a diurnal species in this group. Two others species of Platymantis
(Platymantis cf. “rivularis” and Platymantis spp. E, F) exhibit the unusual pattern of
male parental care. We observed males of these species (n=11) tend to the egg clutch,
putatively as an act of guarding against predators or keeping them free of mildew
(Duellman and Trueb 1994). Finally, we observed carnivory by the Luzon fanged frog (L.
macrocephalus). A large male of this species was observed swallowing whole a large
female of the Luzon stream frog R. luzonensis-the first observation of this kind for a
species of Limnonectes in the Philippines.
Comments on particular species
Platymantis cornuta (Taylor 1922)
Platymantis cornuta was described by Taylor (1922a) based on a single specimen
he collected from the town of Balbalan. Prior to our surveys, only the holotype (CAS
61476), presently deposited at the California Academy of Sciences represented this
species. Our collecting effort resulted in the possible collection of an additional two
samples of this arboreal species. We recommend that future survey efforts must include
the collection of a larger series of specimens of P. cornuta coupled with studies on its
geographic distribution in the Cordilleras. It is listed as Data Deficient by IUCN (2003).
Platymantis sp. (cf. “rivularis”) (Taylor 1922)
Taylor (1922a) described Cornufer (=Platymantis) rivularis from Balbalan, which
was subsequently synonymized by Inger (1954) with P. hazelae, a related species which
is otherwise restricted to high-elevation montane forests in Negros Island (Alcala and
Brown 1998). We suspect one of our Platymantis frogs from BBNP is Taylor’s P. rivularis
and ongoing taxonomic studies will address this issue specifically. One of us (RMB)
has encountered P. hazelae in the field and recognizes extensive differences on morphology
and advertisement calls between these two taxa.
Rana igorota (Taylor 1922)
As with other species from the Cordilleras, Inger (1954) considered Taylor’s R.
igorota as a subspecies of R. everetti. Brown et al. (2000b) eventually established the
taxonomic validity of R. igorota on the basis of Taylor’s original specimens from Balbalan
(the type locality) collected in 1920. We did not find this species on our first visit to
Balbalan in July 1998. But during our second inventory work at BBNP in March 2001,
we discovered a healthy population of this species in just one locality within the park.
We collected a total of 17 specimens considerably increasing the known museum
75
Amphibians and reptiles of Balbalasang-Balbalan National Park
collections for the species. This striking stream frog appears to prefer pristine or little-
disturbed cool mountain streams in lower montane forests.
Brachymeles bicolor (Gray 1845)
This is an extremely rare species of Brachymeles in the Philippines. B. bicolor was
described on the basis of two specimens without precise collection locality data (Gray
1845). More than 140 years later, this species was rediscovered from the northern tip of
the Sierra Madre Mountains of northeastern Luzon (Crombie and Ota unpublished data)
and more recently, at Aurora Memorial National Park in the central Sierra Madres (Brown
et al. 2000a). Our record from BBNP is only the third known locality for this species.
We recommend a full study of the range of morphological variation in the species and
intensive collecting effort to determine its geographic distribution on Luzon.
Sphenomorphus cf. luzonensis (Boulenger 1845)
This is a rare forest species that is known only from a few specimens from the
highlands of Lepanto, Mountain Province and was subsequently collected by R. Crombie
(U.S. National Museum of Natural History) at the Municipality of Bauko, Mountain
Province. Our specimens that we tentatively refer to this species were observed actively
moving through forest litter in sunspots in the forest on dry ridges above Balbalasang.
Typhlopid sp.
Among the most exciting new discoveries from BBNP is a single specimen of a
scolecophidian snake recorded during the 2001 field season. This snake may represent a
record of a new genus for the Philippines and it appears to be related to species from the
Solomons and Bismarck Archipelago (V. Wallach, in litt., 2003). Taxonomic study of
this new species is currently underway and results will be published elsewhere.
Recommendations
Few herpetological collections have been conducted in the mountains of Cordillera
Central in the past, leaving this extensive mountain range for the most part, unstudied.
It is, thus, not surprising that our survey efforts at BBNP resulted in the discovery of an
astonishing number of species that are possibly new to science. This only emphasizes
the extent to which we are relatively ignorant of the herpetological faunal composition
in the Cordilleras. We predict that additional species will be added to the herpetofaunal
list of BBNP provided that more exhaustive field surveys are conducted especially in the
remaining forest habitats at the lower elevations, such as in the Balbalan area, and in
many other isolated mountain peaks within BBNP, such as Mt. Sapocoy.
76 A.C. Diesmos et al.
In the interim, the new materials from BBNP present a rare opportunity to investigate
the systematics of many of the “lost species” from the Cordilleras. The taxonomy of
these species remains questionable up to now. But ultimately, an understanding of the
herpetofauna of BBNP will contribute significantly to further our knowledge base of the
diversity, ecology, and biogeography of the herpetofauna of Luzon Island.
Because we suspect that an under-appreciation of biodiversity is at least one
factor contributing to the non-sustainable exploitation of Southeast Asian forests, it is
critical that adequate survey efforts be conducted to gain a reasonable understanding of
the present biodiversity for enactment of conservation and management efforts.
Large areas of BBNP are still heavily forested and remain intact and its wildlife is
generally in excellent condition. Such a scenario is becoming more uncommon in the
Philippines. The people of BBNP, especially members of the Banao tribe, should be
given all possible encouragement to retain and maintain their age-old tradition and
practices in terms of managing the natural resources of their ancestral land. We believe
that BBNP is a shining example that people can, indeed, live harmoniously with their
environment.
Acknowledgment
We thank the people of Balbalasang for welcoming us into their homes, their community,
and their forest. Our sincere appreciation goes to Brent Banganan (Chairman, Barangay
Balbalasang) and his family for their warm hospitality and support extended to all members of
the expedition. We thank Bernard Malaga, Benedict Dalunag, Jude Marcos, and many others
for their dependable assistance in the field and for sharing their knowledge on the herpetofauna
of BBNP.
We are grateful to Lawrence Heaney (Field Museum, Chicago) for inviting us to work in
BBNP. We are indebted to Angel Alcala for his encouragement and for supporting our interest
in Philippine herpetology for many years. Roy Quiver accompanied us in the preliminary
survey work on Balbalan in 1998 and Willardo Reyes provided important help during the
reconnaissance surveys of BBNP in December 1999. Our field work was made enjoyable in
the company of Danny Balete, L. Heaney, Nonito Antoque, Renato Fernandez, Myrissa Tabao,
Blas Tabaranza, Jr., Aldrin Mallari, Eric Rickart, Sam James, Dan Davison, and Ken Daley.
For facilitating research permits and ensuring our security during survey work at BBNP,
we thank Roquesa De Castro (former Regional Executive Director, DENR-CAR), Clifford Aquino
(former Protected Area Superintendent, BBNP), Leo Viray (Protected Areas and Wildlife
Division), Severino Dalutag and Albert Balnao (CENRO Pinukpuk), Rosendo Dakiwag (Mayor,
Municipality of Balbalan), Edward Cutiyog (Chief of Police, Balbalan), Rafael De Hita (Battalion
Commander), Orlando Buguina (Commanding Officer), and all the gentlemen of the 21st
Infantry Battalion of the Philippine Army.
77
Amphibians and reptiles of Balbalasang-Balbalan National Park
Field work on BBNP was made possible through the generous funding and technical
support of the Field Museum (through L. Heaney) and the Haribon Foundation. For loans of
specimens and provision of working space during museum visits, we thank Robert Drewes,
Jens Vindum, Michelle Koo, (CAS), Roger Sison (PNM), Alan Resetar, Harold Voris, Robert
Inger (FMNH), J. Rosales, and David Cannatella (TNHC). A. Resetar helped in identifying some
of our specimens. The Charles Stearns Fellowship awarded financial support for visits by ACD
and RMB to CAS. This manuscript greatly benefited from critical reviews provided by L.
Heaney, Nina Ingle, and an anonymous reviewer.
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