The of Mt. Irid, Southern Sierra Madre, Luzon Island, 15

The Mammals of Mt. Irid, Southern Sierra Madre, Luzon Island, Philippines

Danilo S. Balete1, Lawrence R. Heaney1, and Eric A. Rickart2

Abstract Introduction Our survey in June 2009 of the mammals of Mt. Irid (ca. The remarkable endemism of the Philippine fau- 1469 m), part of the Irid-Angilo mountain complex that na continues to be augmented by recent discoveries of new includes the highest peak in the Southern Sierra Madre, genera and species, mainly from the island of Luzon. At Luzon Island, documented 16 species of bats and eight present, Luzon has a documented fauna of 44 species of species of non-volant small mammals. The bats consisted non-volant mammals, of which 36 (82%) are unique to of six fruit bats and ten insectivorous bats, including the the island (Balete et al., 2012; Duya et al., 2011; Heaney et first record for Luzon of the lesser tube-nosed bat, Murina al., 2010, 2011, 2013). The majority of the endemic small suilla. The non-volant small mammals consisted of one mammals on Luzon belong to only two endemic clades, and seven murid , of which five rodents are one consisting mainly of ground-dwelling rodents, known native species; the shrew and two other rodents are intro- as earthworm mice (Chrotomys Division), adapted to feed- duced commensal species. One of the native species rep- ing on earthworms and other soft-bodied invertebrates on resents an undescribed species of forest mouse (), the forest floor, and the other comprised of arboreal ro- while the four others are either endemic to Luzon (Apomys dents called cloud (Phloeomys Division) that are spe- microdon and Bullimus luzonicus), to Luzon and Mindoro cialists on seeds and leaves of forest vegetation (Heaney (Chrotomys mindorensis), or widespread in the Philippines et al., 2009; Jansa et al., 2006; Musser & Carleton, 2005; ( everetti). The discovery of an endemic species Rowe et al., 2008). Our studies have shown that most of known only from Mt. Irid establishes the Southern Sierra these endemic species occur in montane and mossy forest Madre as a third subcenter of mammalian endemism in at elevations above ca. 1000 m, becoming more diverse and the Sierra Madre Range, along with the Northern Sierra abundant toward ca. 1500 – 2500 m elevation, on moun- Madre (including Mt. Cetaceo and Mt. Anacuao) and the tains and mountain ranges that are isolated from one an- Central Sierra Madre (including Mt. Mingan). Mt. Irid is other by intervening lowlands. These isolated mountains one of only a few mountains on Luzon of moderate eleva- typically harbor species assemblages that are unique to tion (below 1600 m) known to support an endemic species them and are considered centers of endemism on Luzon. of non-volant small mammal. Mt. Irid serves as an im- The Central Cordillera was the first area on Luzon to be portant watershed for the municipalities of Rizal Province recognized as a center of mammalian endemism based on around the lower western slopes of the Southern Sierra John Whitehead’s discovery of six new genera and eight Madre, and for several major cities of . Thus, new species on Mt. Data (Thomas, 1898). In the course of we recommend the management of Mt. Irid as a protected recent surveys on Luzon to document patterns of mam- area, both for its importance for the conservation of bio- malian diversity, ecology, and biogeography, we have not diversity and its watershed services. only rediscovered long missing species but discovered

1 Department of Zoology, Field Museum of Natural History, 1400 S Lake Shore Drive, Chicago, IL 60605 USA; 2 Natural History Museum of Utah, 301 Wakara Way, Salt Lake City, UT 84108 USA 16 National Museum of the Philippines: Journal of Natural History additional new genera and species from the Cordillera and Madre (A. sierrae), and nearby Mt. Banahaw (A. banahao, other geographically isolated mountains and mountain A. magnus). These results highlight the distinctiveness ranges, including the Mingan mountains, northern Sierra of the Southern Sierra Madre as a distinct biogeographic Madre and Zambales Mountain Ranges in northern and subregion of Luzon. , Mt. Banahaw at the southern edge of central Mt. Irid (1469 m) is also one of the few mountains with Luzon, and Saddle Peak, Mts. Isarog, Labo, and Malinao elevation below 1600 m that we have so far surveyed that in the Bicol Peninsula; nearly all of these areas support en- host at least one locally endemic species of mammal, sim- demic species that occur nowhere else (Balete et al., 2006, ilar to Mt. Labo (1544 m) in Camarines Norte Province. 2007, 2009, 2011, 2012, 2013; Duya et al., 2011; Heaney, In contrast, Mt. Natib (1253 m) and Mt. Malinao (1548 m) 2001; Heaney et al., 2010, 2011, 2013; Rickart et al., 1991, are not known to have species endemic to them; instead 1993, 2011a, 2011b). they share species with the nearby higher mountains (the Broadly defined, the Sierra Madre Range is considered Zambales Mountains and Mt. Isarog, respectively; Balete the longest mountain range in the Philippines, spanning et al., 2013; Rickart et al., 2013). the entire length of the eastern edge of Luzon north of the Bicol Peninsula. There are no extensive lowlands that sep- Study Area and Methods arate the various component highland areas of this range, Location and geology except the narrow gap that marks the northwestward pas- Mt. Irid (1469 m; Figs. 1 & 2A), located near the center of sage of the Philippine Fault at Bay in the Southern Sierra Madre, is the second highest peak of Province. The fault divides the range in two blocks extend- the Irid-Angilo mountain complex, within the political ju- ing north and south of the fault line. Although narrow- risdiction of and Rizal provinces; an unnamed peak ly separated by the fault line (ca. 100 m at the narrowest), (1530 m), adjacent to Mt. Irid, is the highest (Mallari et al., the entire mountain range has a very complex stratigra- 2001). Although we approached Mt. Irid from Barangay phy and geologic history, roughly dividing the range into Fig. 1. Map of Mt. Irid, showing its location on Luzon (inset). Sampling local- three distinct sections: 1) Northern Sierra Madre, includ- ities are indicated by numbers, following the list of study areas (see Methods). ing Mt. Cetaceo and Mt. Anacuao, extending from Palaui Contour interval = 200 m. Island at its northeastern-most tip south to Baler, Aurora Province, 2) Central Sierra Madre, including the Mingan Mountains, from the southern edge of Baler to the northern edge of the Philippine Fault along the Dingalan River, in Dingalan, Aurora Province, and 3) Southern Sierra Madre, from the edge of the Philippine Fault at the southern edge of the Mingan Mountains to its southernmost tip around Atimonan, Quezon Province (Balete et al., 2011; Bureau of Mines and Geo-Sciences, 1982; Heaney et al., 2013). Our previous surveys of three of the highest moun- tains north of the Philippine Fault line (Mt. Cetaceo, Mt. Anacuao, and Mt. Mingan) led to the discovery of several endemic species that indicate two areas of mammalian en- demism, consisting of the Mingan Mountains (1901 m) in the Central Sierra Madre, with at least four endemic mam- mals, and a section centered on Mt. Anacuao (1819 m) in the Northern Sierra Madre, with at least three endemic mammals (Balete et al., 2011, 2012; Danielsen et al., 1994; Duya et al., 2007, 2011; Heaney et al., 2010, 2011, 2013; Rickart et al., 1998). The results of our survey of Mt. Irid in 2009 presented in this paper include the discovery of an- other species of forest mouse, Apomys sp. (Heaney et al., in prep.), distinct from its endemic congeners in the Mingan Mountains (A. aurorae and A. minganensis), Northern Sierra The Mammals of Mt. Irid, Southern Sierra Madre, Luzon Island, Philippines 17

Sta. Ines, Tanay Municipality, our survey covered the upper southern slope of the mountain within the municipality of Rodriguez (formerly called Montalban), Rizal Province. Along the length of our transect, limestone outcrops were abundant in the forest, but it was only near the peak that exposed karst projected above the low canopy vegetation (Fig. 2A). Ultramafic soil on the lower slopes above Sta. Ines was also evident, marked by piles of previously quarried chromite ore abandoned along the trail. Mt. Irid and the adjacent Angilo Mountain feed the headwaters of numer- ous tributaries of four major river systems that separately drain into the East Philippine Sea by way of Dingalan Bay (Umiray River) in the northeast and Polillo Strait (Agos River) in the southeast, and into the West Philippine Sea by way of Manila Bay (Marikina and Pasig Rivers) in the A northwest, and Laguna Lake (through a different branch of the Marikina River) in the southwest (Fig. 1). Geologists define the Southern Sierra Madre, togeth- er with the Bicol Peninsula and the islands of Polillo and Catanduanes, as comprising the Bicol Subprovince of the Eastern Physiographic Province of the Philippines; the Southern Sierra Madre itself forms a distinct geologic unit defined by a complex geological history and stratigraphy (Bureau of Mines and Geo-Sciences, 1982). The Philippine Fault system defines its northern boundary, formed by the fault veering at Dingalan Bay to a westward course along the northernmost limits of the Luzon Central Plain before trending northward into the Cordillera Mountain Range. B The eastern flank of the Southern Sierra Madre runs par- allel to the East Philippine Sea coastline, while its western edge frames the southern extension of the Central Plains. A general flattening of the topographic relief is evident as the Southern Sierra Madre range approaches its southernmost tip, particularly among the mountains along the northern bank of the Mauban River in Mauban, Quezon. South of the Mauban River, topographic relief grows even lower and the flattening of the landscape becomes more pronounced as it approaches the northern bank of Atimonan River in Atimonan, Quezon, beyond which it narrows and merges with the northern end of the Bondoc Peninsula. However, the southern limit of the Southern Sierra Madre is poorly defined; Lamon Bay, which runs from Dalahican down to Atimonan, is cited as its boundary (Bureau of Mines and Geo-Sciences, 1982).

Fig. 2. Upper slopes of Mt. Irid, showing exposed limestone around the peak (A); regenerating lowland forest at edge of subsistence farm, 700 m (B); and primary montane forest with moss-covered vegetation and limestone outcrop, 1330 m C (C). Photos by D.S. Balete, 31 May (A & B) and 20 June 2009 (C), respectively. 18 National Museum of the Philippines: Journal of Natural History

The Southern Sierra Madre stratigraphy, particularly the as Alstonia, Artocarpus, Bischofia, Elaeocarpus, Syzygium, region including Mt. Irid, is characterized by metavolcanics and Mangifera were common. Canopy vines were com- overlain by Upper to Miocene marine strata, mon but not particularly abundant, including lianas, jade with Oligocene dioritic intrusives, with the southern sec- vines (Strongylodon), Tetrastigma, and climbing bamboos tion overlain by Pleistocene lava flows and pyroclastics; the (Dinochloa). Erect palms (Pinanga) and rattans (Calamus) lowlands are overlain with Quaternary alluvium (Bureau were present but uncommon; wild bananas (Musa spp.) of Mines and Geo-Sciences, 1982). No Quaternary vol- were more common. Ground vegetation included grass- canoes are present in the Southern Sierra Madre, but its es, ferns, ground orchids, and Alocasia. Small limestone southern extension from Mauban River is characterized by outcrops were common on the forest floor. There was a predominantly Quaternary volcanic deposits. The mainly thin layer of leaf litter, ca. 0.5 cm - 1 cm, collected around limestone strata and ophiolitic intrusives dating from the tree trunks on flatter ground. The humus layer was thin Upper Cretaceous to Middle Miocene are indicative of the and scattered, ca. 1 cm. submarine genesis of the Southern Sierra Madre up to ca. Locality 2. 1.3 km S, 0.8 km W Mt. Irid peak, 775 m 22 Ma, and prior to the uplift associated with Pleistocene elev., 14.77900º N, 121.31821º E (8 – 10 June 2009). This volcanism, ca. 2 Ma. Similarly, the Northern Sierra Madre area was adjacent to Locality 1; we conducted only netting block is estimated to have existed as dry land from the of bats. Vegetation and forest structure appeared similar Eocene to early Oligocene, 43-50 Ma, followed by submer- to Locality 1, except for the appearance of Tristaniopsis gence from around the Early Miocene (ca. 20 Ma) until and Garcinia. Tetrastigma was also more common here it was uplifted again around the early Pliocene, ca. 5 Ma. than at 700 m. Extensive old and abandoned kaingin sur- Thus, the present Southern Sierra Madre, along with the rounded the area. No leaf litter or humus layer was ap- rest of the Sierra Madre mountain range, is both lower in parent along the trail. elevation and younger as a dry-land area than the Central Locality 3. 1.25 km S., 0.5 km E Mt. Irid peak, 920 m elev., Cordillera, which is estimated to have existed as a large, 14.78000º N, 121.32116º E (7 - 12 and 19 - 22 June 2009). continuous highland area for the last ca. 30 Ma (Hall, 1998, The forest canopy at this locality, including emergents, was 2002; Mitchell et al., 1986; Wolfe, 1988; Yumul et al., 2009). 20 - 35 m high, and had characteristics of transitional low- land/lower montane forest. Common canopy and emer- Study Locations gent trees included Agathis, Lithocarpus, Tristaniopsis, and Our survey covered the forest habitats on the southern Garcinia; dipterocarps were present but uncommon. Vines slopes of Mt. Irid (Figs. 1 and 2). Mt. Irid is a limestone similar to those at Localities 1 and 2 were common here, and mountain overlain with volcanic soil; limestone outcrops Tetrastigma was particularly abundant. Aside from palms, are abundant throughout the mountain, but most evident understory vegetation included Pandanus, Garcinia, and at the peak area where the karst landscape emerges from a few wild bananas (Musa). Gingers (Zingiber), Alocasia, the low forest canopy and surrounding grassy patches. ground orchids, and other herbaceous plants were abun- The vegetation of the mountain consisted of forest over dant on the forest floor. Most notable among the ground limestone (Fernando et al., 2008) that from the lower el- vegetation was Rafflesia sp., which occurred abundantly, evations up to ca. 750 m had been extensively logged or especially along the trails. Limestone outcrops here were cleared for subsistence agriculture (kaingin). Agriculture, more common and larger than at Localities 1 and 2. Leaf settlements, grassland, and small patches of regenerating litter was thicker on flatter ground, ca. 1 - 2 cm thick, and lowland forest comprised the areas below 700 m. We sur- the humus layer was ca. 2 cm thick. veyed five localities from regenerating lowland forest and Locality 4. 0.5 km S, 0.1 km E Mt. Irid peak, 1110 m elev., its grassy and kaingin edges at ca. 700 m to primary upper 14.78659º N, 121.32460º E (14 - 23 June 2009). We sur- montane forest at 1330 m. veyed primary lower montane forest at this site. Trapping Locality 1. 1.5 km S, 1 km W Mt. Irid peak, 700 m elev., was conducted on 14 -19 June 2009, with additional sam- 14.77660º N, 121.31623º E (1 - 6 June 2009). We surveyed a pling of bats and arboreal rodents on 20-23 June 2009. The portion of regenerating lowland forest and adjacent kaingin common species included Agathis, Lithocarpus, Syzygium, and grassland (Fig. 2B). The canopy was open, ca. 25 - and Tristaniopsis, as well as Elaeocarpus and members of 30 m high with emergents up to 40 m. The area showed Lauraceae, Sapotaceae, and Theaceae. The canopy was lower signs of recent cutting of timber and clearings for new than at our lower sites, ca. 20 - 25 m high. Palms, includ- kaingin. Aside from a few dipterocarps (Shorea), trees such ing rattans, and Pandanus were present but uncommon, The Mammals of Mt. Irid, Southern Sierra Madre, Luzon Island, Philippines 19

along with figs (Ficus) and Psychotria. Epiphytes, includ- days, then removed and set elsewhere. Ground trapping ing mosses and lichens, ferns, orchids, and Medinilla were was done mainly with Victor traps. We set them at ca. common and abundant. Vines, particularly Tetrastigma, 5 m inter-trap intervals, along fresh runways, under root were common at this elevation. Rafflesia was also present tangles, and beside or under fallen logs. Arboreal trapping but not as abundant as at Locality 3. Limestone outcrops utilized both Victor and Museum Special traps, and baited were extensive, commonly as large, weathered boulders only with coconut. We set them on overhanging branches, throughout our sampling area. Leaf litter was ca. 2 - 3 lianas, and horizontal branches of trees, from ca. 0.5 - 5 m cm, and the humus layer was up to 3 cm on flatter ground. above ground. At the completion of this trapping effort, we Locality 5. 0.25 km S, 0.15 km W Mt. Irid peak, 1330 m moved to the next study locality. At each locality, we set elev., 14.78878º N, 121.32479º E (20 - 22 June 2009). Our traps in all accessible microhabitats, and slope conditions. sampling was conducted in primary montane forest (Fig. Traps were serviced at least twice daily: early in the morn- 2C), with a low canopy, ca. 10 - 12 m, and up to 15 m for ing after sunrise, and late in the afternoon before sundown emergents. Podocarpus was common at this site, along (ca 07:00 h and 17:00 h, respectively). Each trap set for 24 with Elaeocarpus, Lithocarpus, Syzygium, and members of hours is recorded as a trap-night, our measure of trapping Lauraceae and Sapotaceae. Understory vegetation includ- effort. Specimens recovered during early morning and late ed figs, Psychotria, members of Theaceae, and abundant afternoon were considered as nocturnal/crepuscular cap- Pandanus. Mosses and lichens were abundant on vege- tures, those after 07:00 h until 17:00 h as diurnal captures. tation, ground, and exposed rocks. Medinilla was a com- To survey small fruit bats and insectivorous bats, we mon epiphyte, along with ferns and orchids. Vines were used a combination of 6 m and 12 m mist nets with 36 common, including climbing bamboos, but Tetrastigma mm mesh size. We set them singly or in a series of two was rare. On the ground, ferns, ground orchids, and some or more nets in a line, across potential flyways, including sedges were common. Flowering Rafflesia sp. was also pres- along trails and small streams. The nets were tended con- ent, but uncommon. The accumulated layer of leaf litter on tinuously from around dusk to early evening, ca. 20:00 h, flatter ground was ca. 2 - 3 cm thick, but was absent along and every 30 minutes until 22:00 h. The rest of the night steep slopes. The humus layer was similar to Locality 4. the nets were left open and were checked again early in the morning of the following day. At each locality, the mist Field Methods nets were left in place for three to four consecutive nights. Our survey methods followed the standardized techniques Each mist net left in place for 24 hours was recorded as a of our previous surveys of Philippine small mammals, to net-night, our measure of netting effort. At each locality facilitate comparison of our results (Alviola et al., 2011; we accumulated from six to 28 net-nights, for a total of 71 Balete et al., 2009, 2011; Duya et al., 2011; Heaney et al., net-nights throughout our transect. 1989, 1999, 2006b; Rickart et al.,1991, 1993, 2011a). We Captured individuals were preserved as voucher spec- established our transect on the southern slopes of Mt. Irid, imens, except for some bats that were released. Before a starting at ca. 700 m, in fragments of regenerating lowland specimen was prepared, a small tissue sample was taken forest and adjacent kaingin, up to ca. 1330 m in montane either from the thigh (non-volant mammal) or the chest forest, following a ca. 200 m elevational interval between (bats), and placed in cryotubes with DMSO buffer solu- sampling localities (excluding Locality 2, where only bats tion. Fluid-preserved specimens were first injected with were surveyed; see Study Locations). At each locality we saturated formalin solution, then soaked in 10% buffered sampled within a ca. 50 m elevational band above and be- formalin (and later transferred to 70% ethanol). Other low the central elevation. The coordinates (latitude and specimens were prepared as complete skeletons. We fol- longitude based on the Philippine Luzon Datum) of each lowed Heaney et al. (1998, 2010, 2011) for nomenclature. locality were determined using a hand-held GPS unit. Specimens were deposited at the Field Museum of Natural Distance from the peak of Mt. Irid was computed from the History, Chicago (FMNH), for verification of field identifi- plotted coordinate readings on 1:50,000 topographic maps. cation and further taxonomic studies; half will be returned We used a combination of Victor rat traps and Museum to the National Museum of the Philippines, Manila (NMP) Special snap traps, baited either with fried coconut coated after completion of our studies. We followed all relevant with peanut butter, or live earthworms dug from around our Philippine laws and regulations in the capture and han- camp or near each locality. Each trapline was set for three dling of in the field. 20 National Museum of the Philippines: Journal of Natural History

Data Analysis For sample size lower than 20, we determined the signifi- We determined the number of species recorded at each lo- cance from the binomial distribution at p < 0.05. The low cality from direct captures, plus the inferred occurrence of number of trapping localities did not permit tests for the any species that was not captured at that locality, but was relationship of elevation with species richness, relative caught at localities above and below it (e.g., Rickart et al., abundance, or diel period. 1991). To measure the adequacy or completeness of sam- pling of the non-volant small mammals, we plotted spe- Results cies-accumulation curves, showing the number of species The mammals recorded on Mt. Irid during this survey con- recorded against the accumulated trap-nights at each sam- sisted of 32 species (Tables 1 & 2). The species we captured pling locality (except Locality 2 that was surveyed only for directly included one shrew, six fruit bats, ten insectivorous bats), and for all the sampling localities combined, starting bats, and eight non-volant small mammals. The rest of from the lowest locality. This method of assessment for our records for Mt. Irid were either reported to us by local the completeness of sampling effort for small mammals people and hunters, such as for the cloud rat (Phloeomys has been standard in previous surveys in the Philippines pallidus), Philippine brown deer (Cervus mariannus), civet (Alviola et al., 2011; Balete et al., 2009, 2011; Duya et al., cats (Paradoxurus hermaphroditus and Viverra tangalun- 2011; Heaney, 2001; Heaney et al., 1999, 2006a; Rickart et ga), or observed by us directly but not captured, including al., 1991, 2011a). We do not present species accumulations flying foxes (Pteropus spp.), long-tailed macaque (Macaca curves for bats because sampling effort and netting sched- fascicularis), and Philippine warty pig (Sus philippensis). ules were disrupted due to persistent rain. These species of large mammals on Mt. Irid were heavily To determine ground trap success overall, the number hunted, and were reported to us as having declining pop- of individuals captured was divided by the accumulated ulations on the mountain; they are declining throughout trap-nights, and the result was standardized by multiply- their ranges in most of the Philippines (Heaney et al., 2010). ing it by 100, and expressed as captures/100 trap-nights. Trap success for each bait type was computed similarly, Bats with the number of individuals captured with each bait We accumulated a total of 71 net-nights during our sam- type divided by the relevant trap-nights, and standardized pling of bats, and recorded 16 species of bats, of which six to captures/100 trap-nights. Trap success of our arboreal (38%) were fruit bats and ten (62%) were insectivorous effort was computed separately, since it exclusively utilized bats (Table 1). Of our total capture of 90 individuals, 50 coconut bait. Overall ground trapping success, as a proxy (56%) were fruit bats and 40 (44%) were insectivorous for relative abundance of ground-dwelling small mammals, bats. Except for our lowest study area at 700 m that had was expressed as weighted (by bait type) and unweight- the most disturbed forest and where we recorded only 6 ed (equalized for bait type) percentages of captures. The species of bats, the diversity of bats showed little varia- weighted trap success at each locality was determined by tion (8 - 9 species captured and inferred at each locality). dividing the total number of individuals captured by the The same pattern emerges if we combined the records for total trap-nights at the site, and the quotient multiplied by the two lowland study areas (700 and 775 m) and the two 100 to obtain the percent trap success. The unweighted higher elevation areas (920 and 1110 m); each had a com- trap success was computed by averaging the trap success- bined total of 11 species. es for the two bait types at each locality. Among fruit bats, the common nectar bat (Eonycteris For sample sizes of 20 or more individuals (with at least spelaea) and common rousette (Rousettus amplexicaudatus) 5 individuals/treatment, e.g., elevation, in at least 80% of were captured only at the lowest locality. The remaining the treatments) we used Chi-squared tests to determine the species were found in both lowland and montane forest at significance of differences of the computed trap success by all elevations up to 1110 m; the dagger-toothed nectar bat bait type, trap position, or diel activity pattern from their (Macroglossus minimus) was recorded only at 775 m and expected frequencies calculated from the total number of 920 m. Among fruit bats, the common short-nosed bat relevant trap-nights (see Tables). Expected frequencies (Cynopterus brachyotis) was the most abundant, particular- for diel period were computed using a 10:14 ratio (hours ly at 700 m; both the Luzon pygmy fruit bat (Otopteropus in a 24-hour circadian cycle corresponding to presumed cartilagonodus) and musky fruit bat (Ptenochirus jagori), duration of diurnal and nocturnal/crepuscular activity pe- on the other hand, showed low but consistent abundance. riods, respectively, of the small mammals at the locality). We observed flying foxes at our camp at 700 m that we The Mammals of Mt. Irid, Southern Sierra Madre, Luzon Island, Philippines 21

Table 1. Distribution of bats along the elevational gradient on Mt. Irid, Rizal Province.

Locality and Elevation (m) 1 2 3 4 Scientific Name Common Name Total 700 775 920 1110 Cynopterus brachyotis common short-nosed fruit bat 22 1 0a 2 25 Eonycteris spelaea common nectar bat 4 0 0 0 4 Macroglossus minimus dagger-toothed nectar bat 0 2 1 0 3 Otopteropus cartilagonodus Luzon pygmy fruit bat 1 1 1 1 4 Ptenochirus jagori musky fruit bat 2 3 2 4 11 Rousettus amplexicaudatus common rousette 3 0 0 0 3 Megaderma spasma common Asian ghost bat 0 1 0a 1 2 Rhinolophus arcuatus arcuate horseshoe bat 0 3 3 19 25 Rhinolophus subrufus small rufous horseshoe bat 0 0 2 3 5 Harpiocephalus harpia hairy-winged bat 0 0 0 1 1 Kerivoula whiteheadi common woolly bat 0 0 0 1 1 Murina cyclotis group round-eared tube-nosed bat 0 2 0 0 2 Murina suilla group tube-nosed bat 0 0 1 0 1 Myotis muricola whiskered myotis 0 1 0 0 1 Pipistrellus javanicus Javan pipistrelle 0 0 0 1 1 Tylonycteris pachypus lesser flat-headed bat 1 0 0 0 1 Locality Total 33 14 10 33 90 Number of net-nights 16 6 21 28 71 Number of species 6 8 6 + 2a 9 16

a Presence inferred from occurrence at higher and lower localities were unable to identify to species, but based on infor- pachypus). One of the notable species we found on Mt. mation from local hunters and indigenous people, both Irid was a small species of tube-nosed bat (Murina suil- Acerodon jubatus and Pteropus vampyrus occurred in the la group), a new record for Luzon, which we recorded at area. Both species were reported to roost at a place in the ca. 920 m, in transitional lowland/lower montane forest. forest far from our camp. Previously, this bat was known only from Mindanao, Cebu, The species composition of insectivorous bats differed and Palawan (Heaney et al., 2010). A related and larger among our netting localities (Table 1). Only two species species, the round-eared tube-nosed bat (Murina cyclotis were present or inferred at all study localities from ca. 775 group) was found at ca. 775 m, in regenerating lowland m up to 1110 m – the common Asian ghost bat (Megaderma forest, along with the whiskered myotis (Myotis muricola). spasma) and a morphotype of the arcuate horseshoe bat (Rhinolophus arcuatus group) with a medium-size body Non-volant small mammals and narrow sella. Because of low capture rates, the major- Our transect covered the forest over limestone on Mt. ity of the insectivorous bats we documented did not show Irid, ranging from regenerating lowland forest at 700 m any clear pattern of elevational distribution. (Locality 1) and transitional lowland/montane forest at 920 Our study area in lower montane forest at 1110 m (where m (Locality 3), to montane forest at 1110 m and 1330 m we had the most intensive netting effort) had the highest (Localities 4 and 5, respectively). Our total trapping effort diversity of insectivorous bats; six of the ten species were amounted to 4,029 trap-nights, of which 3,190 trap-nights found there, including our only records of the hairy-winged (79%) were on the ground surface and 839 trap-nights (21%) bat (Harpiocephalus harpia), common woolly bat (Kerivoula were on trees and vines above ground (Table 2). Sampling whiteheadi), and Javan pipistrelle (Pipistrellus javanicus). effort ranged from 450 - 983 ground trap-nights and 136 - At our most disturbed study area at ca. 700 m, in contrast, 318 arboreal trap-nights at each locality. We captured 116 we documented only the lesser flat-headed bat (Tylonycteris native small mammals of five species and 21 individuals of