UNIVERSITY OF ILLINOIS LIBRARY AT URBAiMA-CHAMPAIGN BIOLOGY I t- 0 It 10 H 1 3 ft oology SERIES, NO. 95 Mammalian Diversity on Mount Isarog, a Threatened Center of Endemism on Southern Luzon Island, Philippines Lawrence R. Heaney Danilo S. Balete Eric A. Rickart Ruth C. B. Utzurrum Pedro C. Gonzales September 30, 1999 Publication 1504 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY Information for Contributors to Fieldiana i References: [n [3, Bureau Illustrations: 11 nted on boards in tin ; upon pub Proofs: / 6: ® This paper meets the requirements ot ANSI/NISO Z39.48-1992 (Permanence of Paper). FIELDIANA Zoology NEW SERIES, NO. 95 Mammalian Diversity on Mount Isarog, a Threatened Center of Endemism on Southern Luzon Island, Philippines Lawrence R. Heaney Department of Zoology Field Museum of Natural History Roosevelt Road at Lake Shore Drive Chicago, Illinois 60605-2496 U.S.A. Danilo S. Balete Eric A. Rickart Ruth C. B. Utzurrum Pedro C. Gonzales Note: Remaining authors ' affiliations and current addresses may he found on page Hi. Accepted May 29, 1998 Published September 30, 1999 Publication 1504 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY © 1999 Field Museum of Natural History ISSN 0015-0754 PRINTED IN THE UNITED STATES OF AMERICA Contributors Lawrence R. Heaney Department of Zoology Field Museum of Natural History Roosevelt Road at Lake Shore Drive Chicago, Illinois 60605-2496 USA Danilo S. Balete Department of Zoology Field Museum of Natural History Roosevelt Road at Lake Shore Drive Chicago, Illinois 60605-2496 USA Current address: Haribon Foundation for the Conservation of Natural Resources 9A Malingap Street Teachers Village Dili man 1 1 00 Quezon City, Philippines Eric A. Rickart Utah Museum of Natural History University of Utah Salt Lake City, Utah 84112 USA Ruth C. B. Utzurrum Department of Biology Silliman University 6200 Dumaguete City Negros Oriental, Philippines Current address: Department of Biology Boston University 5 Cummington Street Boston, Massachusetts 02215 Pedro C. Gonzales Zoology Section Philippine National Museum Manila, Philippines fable of Contents abstract 1 introduction 2 Itudy Area and Methods 4 Geology of the Mount Isarog Area 4 Climate of Mount Isarog 5 Study Sites 6 Methods 14 Accounts of Species 16 Order Insectivora 16 Order Chiroptera 17 Order Primates 32 Order Rodentia 33 Order Carnivora 48 Order Artiodactyla 49 Analysis and Discussion 50 Adequacy of Sampling 50 Patterns of Species Richness and Relative Abundance of Small Fruit Bats 52 Patterns of Species Richness and Relative Abundance of Nonvolant Small Mam- mals 53 Patterns of Species Richness of Microchi- ropteran Bats 54 Biogeography 54 Distribution and Ecology of Non-native Species: Are They a Threat to Native Murids? 55 Conservation and Management of the Mount Isarog Mammalian Fauna 56 Conclusions 57 vcknowledgments 58 JTERATURE ClTED 58 ist of Illustrations 1. Map of southern Luzon and adjacent regions 3 2. Old-growth forest cover on southern Lu- zon and adjacent islands 4 3. Mean daily rainfall on Mount Isarog and in adjacent lowlands 6 4. Average minimum and maximum tem- perature on Mount Isarog and in adja- cent lowlands 7 5. Map of Mount Isarog showing locations of sites described in the text 8 6. Deforestation on Mount Isarog at ca. 300 m 9 7. Habitat at Site 2, 900 m 10 8. Habitat at Site 3, 1125 m 10 9. Habitat at Site 5, 1550 m 11 10. Habitat just below summit of Mount Is- arog at ca. 1900 m 12 11. Crocidura grayi 16 12. Elevational distribution of native shrews and murid rodents 17 13. Elevational distribution of fruit bats 18 14. Palm leaf "tented" by Cynopterus brachyotis 19 15. Otopteropus cartilagonodus 23 16. Elevational distribution of insectivorous bats 28 17. Adult Apomys microdot*, A. musculus, and Batomys granti 34 18. Weight of Apomys musculus captured in mossy forest 37 19. Age structure of Apomys musculus in mossy forest 37 20. Reproductive condition of Apomys mus- culus in mossy forest 38 21. Archboldomys luzonensis 38 22. Chrotomys gonzalesi 41 23. Phloeomys cumingi 42 24. Rattus everetti and R. tanezumi 47 25. Rhynchomys isarogensis 48 26. Elevational distribution of large mam- mals 49 27. Species-effort curve for fruit bats cap- tured 51 28. Numbers of small fruit bats recorded along elevational gradients on Mounts Isarog, Pangasugan, and Guinsayawan ... 52 29. Relative abundance of small fruit bats recorded along elevational gradients on Mounts Isarog, Pangasugan, and Guin- sayawan 53 30. Relative abundance of small mammals recorded along elevational gradients on Mounts Isarog, Pangasugan, and Guin- sayawan 54 List of Tables 1 . Summary of vegetation analysis in mossy forest on Mount Isarog 13 2. Density of leaf-litter and soil inverte- brates in mossy forest on Mount Isarog .. 14 3. Biomass of leaf-litter and soil inverte- brates in mossy forest on Mount Isarog .. 14 4. Abundance and elevational distribution of fruit bats on Mount Isarog 18 5. Measurements of fruit bats from Mount Isarog 20 6. Measurements of Emballonura, Mega- derma, and rhinolophid bats from Mount Isarog 26 7. Abundance and elevational distribution of insectivorous bats on Mount Isarog ... 29 8. Measurements of vespertilionid bats from Mount Isarog 30 9. Measurements of murid rodents (Apo- mys, Archboldomys, Batomys, and Chro- tomys) from Mount Isarog 34 10. Density and biomass estimates of mu- rid rodents in mossy forest on Mount Isarog 36 1 1 . Measurements of murid rodents (Phloeomys, Rattus, and Rhynchomys) from Mount Isarog 44 12. Composition of viverrid scats from Mount Isarog 47 VI Mammalian Diversity on Mount Isarog, a Threatened Center of Endemism on Southern Luzon Island, Philippines Lawrence R. Heaney Danilo S. Balete Eric A. Rickart Ruth C. B. Utzurrum Pedro C. Gonzales Abstract Field studies were conducted on Mount Isarog in southern Luzon Island between 1988 and 1995 in all native habitat types (lowland, montane, and mossy rain forest) from ca. 400 m to the peak at 1966 m elevation. Forty-three species of mammals are present: 2 insectivores, 25 bats, 1 primate, 1 1 rodents, 2 carnivores, and 2 ungulates. Five additional species, including three bats and two rodents, are known from nearby localities. During these studies, four species were recorded from Luzon for the first time: Harpyionycteris whiteheadi, Harpiocephalus har- pia, Kerivoula hardwickii, and Philetor brachypterus. Three species are endemic to Mount Isarog (Archboldomys luzonensis, Chrotomys gonzalesi, and Rhynchomys isarogensis), one oth- er is known only from southern Luzon {Phloeomys cumingi), and three others are widely distributed on but endemic to Luzon {Otopteropus cartilagonodus, Apomys microdon, and Ba- tomys granti). We suspect that more species of insectivorous bats and large fruit bats remain to be found on Mount Isarog, but our data indicate that insectivores, rodents, small fruit bats, and large mammals are probably completely sampled. Fruit bats are most diverse and abundant in the lowland rain forest, declining rapidly above the upper edges of lowland forest at ca. 1000 m elevation. Insectivorous bats also decline in diversity with increasing elevation, and with the exception of one species that was especially abundant at middle elevations (Pipistrellus java- nicus), abundance followed the same pattern. Nonvolant small mammals increased markedly in diversity and abundance with increasing elevation, with most species absent below the lower edge of montane forest. All but one of the species of large mammals once occurred at virtually all elevations, but overhunting combined with deforestation has decimated populations at lower elevations. Non-native mammals are virtually absent in natural habitat on Mount Isarog, even though several species are abundant in nearby agricultural and residential areas. Based on patterns observed on Mount Isarog and elsewhere in the Philippines, we propose the hypothesis that the richness of the native small-mammal community influences the success of non-native small mammal species in invading natural habitats: where few or no native species are present, non- natives flood into the forest, but where many native species are present, few or no non-native species are able to invade. Bats that require caves as roosting sites are apparently among the most threatened species that occur on or near Mount Isarog; three such species (Eonycteris robusta, Hipposideros bicolor, and H. pygmaeus) may be locally extinct. Overhunting has greatly reduced the number of large flying foxes and all species of large mammals; in the current conditions of virtually no protection, at least one species (Cervus mariannus) may soon be extinct on the mountain. Several species that require old-growth lowland forest have been greatly reduced in number FIELDIANA: ZOOLOGY, N.S., NO. 95, SEPTEMBER 30, 1999, PP. 1-62 by deforestation. Protection of the remaining forest, both old growth and second growth, is essential to the survival of a remarkable and unique set of species. Introduction At over 108,000 km2, Luzon is one of the larg- est islands in the Pacific Ocean. With at least 21 endemic species of mammals (Heaney, 1993; Heaney et al., 1998; Rickart et al., 1998), it also supports one of the largest endemic faunas of mammals, especially when relative area is consid- ered (Heaney, 1986; Heaney & Regalado, 1998; Heaney et al., 1998; Rickart & Heaney, 1991; Rickart et al., 1991). Indeed, it was the discovery of the exceptionally diverse rodent fauna of the mountains of north-central Luzon by John White- head in 1895 (Thomas, 1898) that led to much of the early interest in the mammals of the Philip- pines (Sanborn, 1952; Taylor, 1934). Repeated surveys of the highlands of northern Luzon have led to a common perception that the mammal fau- na of Luzon may be the best known in the country (Manuel, 1935; Rabor, 1955; Sanborn, 1952). However, recent studies have shown that this is unlikely to be the case. In particular, the discovery and naming of three highly distinctive endemic species of mammals from southern Luzon during the past 15 years (Archboldomys luzonensis Mus- ser, 1982b; Rhynchomys isarogensis Musser & Freeman, 1981; Chrotomys gonzalesi Rickart & Heaney, 1991) and the earlier description of a small fruit bat that is widespread on Luzon (Otop- teropus cartilagonodus Kock, 1969), plus the de- scription of a new species of Archboldomys from northeastern Luzon (Rickart et al., 1998), clearly demonstrate the inadequacy of earlier faunal in- ventories. Moreover, until very recently, almost no information on the ecology and conservation status of mammals from Luzon was available (e.g., Oliver et al., 1993a; Ruedas et al., 1994). In 1988, four of the present authors and several colleagues spent 4 months conducting surveys of mammals and other taxa in the southern Luzon region, beginning with Catanduanes Island and proceeding to Mount Isarog (Heaney et al., 1991; Fig. 1). We chose to focus on southern Luzon be- cause preliminary data indicated that the Bicol Peninsula and associated smaller islands had a fauna somewhat distinct from that of northern Lu- zon, and it was clearly the more poorly known of the two regions (Heaney, 1986). Our work on Ca- tanduanes resulted in a more complete under- standing of the birds (Goodman & Gonzales, 1989) than was available previously (Gonzales, 1983), and in the first report on the mammals of that island (Heaney et al., 1991). Our initial stud- ies on Mount Isarog, which immediately followed our fieldwork on Catanduanes, yielded an exten- sive assessment of the avifauna of the mountain (Goodman & Gonzales, 1990), an analysis of community structure of nonvolant small mammals along an elevational transect (Rickart et al., 1991), the description of the southern Luzon shrew-rat {Chrotomys gonzalesi) mentioned above, and one of the first surveys of tropical ants along an ele- vational gradient (Samson et al., 1997). In 1989, 1990, and 1993-1994, one of us (D. S. Balete) returned to the mountain for further faunal studies in conjunction with the development of a conser- vation management program for Mount Isarog National Park, which encompasses the entire mountain, and for research for a Master's degree thesis (Balete, 1995; Balete & Heaney, 1997). In the course of this and other faunal invento- ries (Heaney et al., 1989; Rickart et al., 1993), it has become clear to us that knowledge of Asian mammals in general and Philippine mammals in particular is critically limited. Past studies, though yielding much important information, have rarely been conducted in an intensive, systematic fash- ion that yielded comprehensive faunal analyses of mammals for given regions. In particular, mam- mals that occur in low densities, those that occur at high elevations, and small species, especially insectivorous bats, have been inadequately sam- pled, so that our knowledge of local diversity pat- terns is quite poor. Moreover, as we have come to recognize that variation in diversity and abun- dance along elevational gradients plays a central role in determining general geographic patterns of diversity and abundance (Heaney et al., 1989; Rickart, 1993; Rickart et al., 1991), we have learned just how little precise information on di- versity can be extracted from past surveys (Mus- ser & Heaney, 1992). We have thus come to re- alize the great importance of establishing "bench- mark sites," i.e., places where investigation is suf- ficiently intensive that we can develop an accurate picture of patterns of diversity, so that we may then evaluate the degree to which other studies may be incomplete indicators of diversity. We FIELDIANA: ZOOLOGY Fig. 1 . Map of southern Luzon and adjacent regions, indicating the position of islands and mountains referred to in the text. The hypothesized extent of dry land during the late Pleistocene (ca. 18.000 years ago), when sea level dropped to 120 m below the present level, is shown. chose Mount Isarog as one of the places where we would conduct such a benchmark study. A final and more compelling reason drew us to choose southern Luzon as a study area. When Europeans first arrived in the Philippines, most of Luzon was covered by old-growth rain forest, which was the natural vegetative cover of nearly all of the island. By 1870, old-growth rain forest still covered over half of the land in the southern portion of Luzon and most of the adjacent smaller islands (Fig. 2). By the beginning of the American colonial period, in 1902, this had been reduced somewhat, but an acceleration in the rate of de- struction of natural habitat was apparent. By 1960, rain forest cover was limited to high moun- tains and rugged, inaccessible regions, and by 1986 it had receded to cover at most 10% of the region (Fig. 2). An aerial survey in 1992 disclosed that forest on Mount Isarog was "slowly being degraded by numerous poaching operations" (De- velopment Alternatives, Inc., 1992). Deforestation has increased the intensity of floods and droughts because little forest is present to soak up rainfall and release it gradually; monthly rainfall on Mount Isarog can exceed 2 m, as documented be- low. The function of forest as watershed protec- tion is critical, and absence of watershed forests is now causing increasingly severe economic problems throughout the Philippines (Heaney & Regalado, 1998; Myers, 1988). Reduction and fragmentation of the native habitats will also make populations of animals increasingly vulner- able to extinction because small populations are more vulnerable than large populations to natural disasters (fires, floods, droughts, and disease) and to the direct effects of human disturbance (hunt- ing and other forms of disruption). We viewed our study as an attempt to document the diversity of southern Luzon while an area still remains that supports most of the native mammal fauna. Our studies on the birds of Mount Isarog National Park, conducted concurrently with those on mam- mals reported here, have shown that 42% of the lowland birds once present on Mount Isarog are now locally extinct (Goodman & Gonzales, 1990). This finding clearly demonstrates that the native vertebrate species are highly vulnerable and raises the prospect that native mammal spe- cies may also have become locally extinct. This issue is addressed below. HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 123° 122° _l 124° J 122° _J 123° _l 124° J Fig. 2. Maps of forest cover on southern Luzon and adjacent islands in ca. 1870 (Anonymous, 1876), ca. 1900 (Anonymous, 1905), 1960 (Huke, 1963), and 1987 (National Mapping and Resource Information Authority, 1988), showing the progressive loss of old-growth forest on southern Luzon and adjacent islands. Most remaining old-growth forest fragments are restricted to areas above 1000 m elevation on isolated mountains or in rugged areas dominated by exposed limestone ridges. This report summarizes distributional, system- atic, and ecological information on all of the mammal species that we documented on Mount Isarog, and it presents the results of our eleva- tional transect study of fruit bats, which parallels that of rodents and insectivores published else- where (Rickart et al., 1991). The purpose of this paper is to summarize all of the currently avail- able information on the mammal fauna of the park. Because of the importance of, but lack of previous information about, mossy forest habitats and mammal communities, we provide more ex- tensive and detailed data on this than on any other habitat. Study Area and Methods Geology of the Mount Isarog Area Mount Isarog is an extinct volcano surrounded by lowland plains. Rising to 1966 m, it is the highest forested peak on southern Luzon; the only higher peak, Mount Mayon (2462 m), is an active volcano covered by barren volcanic ash over most of its upper elevations. Southern Luzon is a part of the Eastern Philippine Rim Structural Region and lies just to the west of the northern portion of the Philippine Trench, where the Pacific Plate FIELDIANA: ZOOLOGY is actively subducted below the Philippines (Ham- ilton, 1979; Holloway, 1981). The geological his- tory of the area is complex (Hall, 1996). Recent evidence indicates that the southeast portion of Luzon originated as the northernmost extension of an arc system that gave rise to mod- ern Samar and much of Mindanao. This arc sys- tem originated to the southeast of its current lo- cation and came into close juxtaposition with cen- tral and northern Luzon (and the central and west- ern Visayas) only in the late Miocene/early Pliocene (Fuller et ah, 1983; Hall, 1996; Mitchell et al., 1986). The Philippine Fault, which runs along the eastern edge of the Bicol Peninsula to its northern tip, where it then trends northwest- ward and forms the boundary between southern and central Luzon, is associated with the ongoing interaction between these two major land masses (Hamilton, 1979). Volcanic activity and uplifting during Pliocene to Recent times associated with this subduction has produced 12 stratovolcanoes in the Bicol arc of southern Luzon, with three especially promi- nent basaltic/andesitic cones (Fig. 1): Mount Is- arog (1966 m), Mount Mayon (2462 m), and Mount Bulusan (1558 m), as well as islands such as Catanduanes, which lies about 60 km to the east of Mount Isarog (Hamilton, 1979; Hashimo- to, 1981; Philippine Bureau of Mines, 1963). Dated volcanic materials from the region of Mount Malinao (Fig. 1) are young, the oldest dated at only 3.2 and 3.4 million years ago (Ma), with many dates in the range of 0.4-0. 1 6 Ma, and some are current (Knittel-Weber & Knittel, 1990). To the best of our knowledge, the volcanics from Mount Isarog have not been dated. The region is subject to frequent earthquakes; we experienced one recorded at 6.9 on the Richter scale during our 1988 season on Catanduanes, and we felt fre- quent minor shocks on Mount Isarog during the following months. During the late Pleistocene (i.e., from about 25,000 to about 10,000 years ago), sea level dropped to about 120 m lower than at present (Fairbanks, 1989; Heaney 1986, 1991), uniting many of the current Philippine islands into larger islands. The present island of Luzon is the largest but not the only land mass that made up the late Pleistocene island of Greater Luzon; other por- tions formed the current Catanduanes, Marin- duque, and Polillo, as well as some smaller is- lands (Fig. 1). Climate of Mount Isarog Mount Isarog lies in one of the principal ty- phoon tracks in eastern Asia, and rainfall is thus both abundant and seasonal, with a period of max- imum rainfall from June to December and a rel- atively dry period roughly from January through May. The mountain usually is subject to severe storms from September to December. Mean an- nual precipitation at Naga City (elevation ca. 50 m, ca. 20 km west of the summit, data for 37 years) is 235 cm, with minimum and maximum monthly means of 6.9 and 30.9 cm in March and November, respectively (Manalo, 1956). Weather conditions varied during the duration of our study. In March 1988, rain was frequent and often heavy, and soils generally were saturated. In late April and early May 1988, rain was infrequent, mean subcanopy air temperatures were warmer, and lower elevations were conspicuously drier. Even on rainless days, however, areas above 1500 m were subject to regular dense fog, resulting in significant surface condensation. During the 1988 study period, subcanopy air temperature ranges were 17.5-30°C at 475 m and 1 0.0-23. 9°C at 1750 m elevation. Limited data from the central Philippines indi- cate that mid-elevation mountain regions (800- 1 100 m) receive up to three times as much rainfall as adjacent lowlands (Heideman & Erickson, 1987); we therefore anticipated that annual rain- fall high on the mountain would be 5,000 mm or more. Balete (1995) measured rainfall at 1650 m (Site 18) on 141 days from the last week of No- vember 1993 to the middle of May 1994 and re- corded 5,713 mm. He estimated that about 8,800 mm fell during the 6-month wet season (which began in September), based on comparison with the adjacent lowlands, and that about 12 m fell during the entire year. Figure 3 shows that the heaviest precipitation occurred during December (daily mean of 74 mm, range 0-144 mm) and the least in February (daily mean of 20 mm, range 0- 97 mm). The adjacent lowlands near Naga City received 1,112 mm during the same days that 5,713 mm fell at the 1650 m site, with total pre- cipitation from 1 November 1993 to 15 May 1994 of 1,422 mm. Monthly totals (and daily means) for the lowlands ranged from 34.6 mm ( 1 .2 mm) in February to 883.2 mm (28.5 mm) in December. The temperature range at 1550 m (Fig. 4) mea- sured by Balete (1995) was similar to that record- ed during 1988 (Rickart et al., 1991), with a low of 10.0°C in February 1994 to a high of 24.5°C HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES Nov Dec Jan Feb Mar Apr May 93 94 Fig. 3. Mean daily rainfall on Mount Isarog in mossy forest at 1550 m elevation (Site 5) and at 60 m elevation, Camarines Sur State Agricultural College, in the adjacent lowlands, November 1993 to May 1994. Number of days of observation at Site 5 (1550 m) were 7 (November), 27 (December), 31 (January), 28 (February), 28 (March), 8 (April), and 12 (May). in March 1994. In comparison, the lowlands near the base of the mountain had much higher tem- peratures. Average monthly low temperatures from November 1993 to May 1994 ranged from 20.9°C in February to 22.TC in November; the lowest temperature recorded, 17.0°C, was attained on 17 February. Average monthly highs during this period ranged from 34.8°C in May to 29.9°C in January; the highest temperature, 36.0°C, was reached twice, on 1 1 April and 3 May. In general, temperature showed little variation throughout the year (Fig. 4), with most seasonality instead being associated with rainfall. Study Sites Mount Isarog (summit at approximately 13°40'N, 123°23'E) has a form typical of many extinct volcanoes in the Philippines (Figs. 5 and 6). The top of the mountain consists of a semi- circular ridge (1850-1950 m elevation) constitut- ing the western flank of the former volcanic cone. The western and southern slopes are moderately steep and are cut by several large river channels. The eastern side, bordering the large interior cra- ter, is extremely steep. On the western and southern slopes of Mount Isarog, the natural vegetation below 900-1000 m was lowland dipterocarp forest (sensu Brown, 1919) characterized by a complex multistoried structure, heavy buttressing of canopy trees, high tree species diversity with a predominance of Dip- terocarpaceae, abundant lianas, relatively few epi- phytes, and an open understory with sparse ground cover. At the time of our studies, the sur- rounding lowland plains and the western and southern slopes of the mountain up to about 400 m were entirely deforested with the exception of a few small, isolated patches of secondary forest along steep river channels. Between 400 and 800 m, most areas of forest had been cut for timber production and cleared for agriculture. Remnant dipterocarp forest below 800 m was heavily dis- turbed and confined to river channels, but was generally contiguous with old-growth forest at higher elevations (in this publication, we refer to "old-growth" rather than "primary" forest in rec- ognition of the disturbance associated with rattan and medicinal plant collectors and the potential for some small-scale clearing in the past). In the vicinity of the Panicuason Reforestation Station (Site 1 ; 475 m), many areas between 400 and 600 m that were contiguous with secondary forest had been replanted with a mixture of fast-growing trees, including exotic Amazonian mahogany (Sweitenia macrophylla) and an exotic legume lo- cally called ipil-ipil (Leucaena leucocephala). By 1992, most of the grassland on the southern slope up to 500 m had been replanted with narra (Pte- rocarpus indicus), as well as the non-native trees FIELDIANA: ZOOLOGY u 40 30 20 10 Min. - Site 5 Max. - Site 5 Min. - CSSAC Max. - CSSAC Fig. 4. Average minimum and maximum temperature on Mount Isarog at 1550 m elevation (Site 5) and at 60 m elevation in the adjacent lowlands (Camarines Sur State Agricultural College), November 1993 to May 1994 (see Climate section). Falcata sp. and Gmelina sp., as part of a local community reforestation program. During the 1988 study, the lower limit of old growth forest on the western and southern sides of the mountain was at about 900 m. Above this altitude, human disturbance was limited to occa- sional collection of rattan {Calamus and allied genera) and medicinal plants, and to hunting of birds and the few remaining monkeys (Macaca fascicularis), pigs (Sits philippensis), and deer (Cervus mariannus). Above 900 m on the western slope was a steep escarpment of about 100 m con- stituting a zone of transition between lowland dip- terocarp forest and montane forest (midmountain forest, sensu Brown, 1919; lower montane rain forest, sensu Whitmore, 1984). Montane forest, which extended up to ca. 1500 m on the western and southern slopes, was characterized by an open, two-storied canopy structure, a transition from tree buttresses to stilt roots, a reduction in the number of dipterocarps with an attendant in- crease in oaks (Lithocarpus), a well-developed understory, abundant lianas and vascular epi- phytes, and development of soils with high organ- ic content. Above 1500 m, there was a gradual transition from montane forest to mossy cloud forest (upper montane rain forest, sensu Whit- more, 1984), which continued to the summit. Tree size and woody plant species diversity continued to decline and epiphyte loads increased (particu- larly mosses and liverworts). Additional photo- graphs and descriptions of the study area were provided by Goodman and Gonzales (1990) and Heaney and Regalado (1998). We conducted studies on Mount Isarog during three periods. During the first (1-30 March and 20 April-7 May 1988), we surveyed small mam- mals along an elevational transect on the western side of the mountain (Fig. 5, Sites 1-6), with two field teams operating simultaneously at different sites during most of the study. The transect con- sisted of six study sites centered at 475, 900, 1125, 1350, 1550, and 1750 m elevation (Fig. 5); studies at these sites formed the basis for publi- cations on birds (Goodman & Gonzales, 1990), ants (Samson et al., 1997), and non volant small mammal distribution and ecology (Rickart et al., 1991). During the second period (November 1989-February 1990), we surveyed sites on the southern side of the mountain (Fig. 5, Sites 7- 17); investigations were less extensive during this phase. During the third period (November 1993- May 1994), D. S. Balete returned to the western side of the mountain and conducted a capture- mark-recapture study at ca. 1650 m (Site 18), be- tween Sites 5 and 6 (Balete, 1995). Brief site de- scriptions and inclusive dates of survey follow. Site 1 — 4 km N, 18 km E Naga, 475 m elev., HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES A 1990- 1994 o 1988 □ 1961 13"40 Park Boundary 13°35 123u25' Fig. 5. Map of Mount Isarog showing the boundaries of the National Park and location of sites described in the text. Modified from Goodman and Gonzales (1990). Circles show the locations of 1988 sampling sites; triangles indicate the 1989-1994 sites; squares show the approximate locations of Rabor's 1961 sites "above Curry." "PLDT" marks the location of a Philippine Long Distance Telephone relay station. 13°40'N, 123°20'E (3-11 March; 4-8 May 1988). Sampling at this site was conducted in the vicinity of the Panicuason Reforestation Station in a mo- saic of disturbed lowland dipterocarp forest ad- jacent to the Yabo River, a ca. 25 -year-old forest plantation of a non-native legume (Leucaena leu- cocephala) and mahogany (Vitex sp.) with a well- developed understory of native vegetation and brushy or open habitat used for agriculture and grazing. Sampling was done in disturbed forest and forest plantation areas along the steep river- banks. In both habitats there was an extensive un- derstory of figs (Ficus spp.), piper (Piper spp.), saplings (primarily Dipterocarpaceae), small palms, and tree ferns (Cyathea spp.). Woody li- anas were abundant in secondary forest, but most of the rattan had been harvested. There was a sparse ground cover of ferns and herbaceous di- cots, with a thin layer of leaf litter over stony soil composed of weathered volcanic rock. During the period of 23-31 March, several members of the crew, led by P. C. Gonzales, worked the area of scrubby second-growth forest, tree plantations, and agricultural land just below the Reforestation Station. They focused on sur- veys of birds (Goodman & Gonzales, 1990) but also captured bats and one Crocidura grayi and one Phloeomys cumingi. Because the bats were captured incidentally to other work, they are not included in our standardized comparison of sites. Site 2—5 km N, 20 km E Naga, 900 m elev., 13°40'N, 123°21'E (3-11 March, 30 April-4 May 1988). Located at the base of a steep escarpment (up to 45° slope) in an area of lowland dipterocarp forest with some elements of montane forest (Fig. 7), this site was a mosaic of old-growth forest, FIELDIANA: ZOOLOGY Fig. 6. West face of Mount Isarog. from below Site 1 at ca. 300 m elevation, showing deforestation at lower elevations. May 1988, L. R. Heaney. recently logged areas, and small areas of recent agricultural cultivation. Our efforts were concen- trated in old-growth dipterocarp forest with a bro- ken canopy at 20-30 m. The largest trees had di- ameters at breast height (dbh) of 0.5-1.5 m and moderate buttress development. The understory consisted of tree ferns, bamboo (Bambusa spp.), small palms, and saplings. Woody vines, climbing bamboo {Schizostachyum spp.), and climbing pan- dans (Freycinetia spp.) were common, and some rattan was present. Vascular epiphytes, including orchids, ferns, and pitcher plants (Nepenthes spp.), were common, and some moss was present on tree trunks and on dead wood. There was a moderate ground cover of pandans, ferns, and sedges (Cyperaceae). Leaf litter was not exten- sive, but there was a moderate humus layer. Site 3^.5 km N, 20.5 km E Naga, 1125 m elev., 13°40'N, 123°22'E (23-30 March, 26 April-4 May 1988). The third site was located in lower montane forest (Fig. 8) with an overall slope of ca. 25°; canopy trees ranged from 18 to 25 m in height with dbh from 0.25 to over 0.5 m. Most large trees were not buttressed. Some moss was common on both dead wood and live trees. At both this and the 1350 m site, the understory consisted of saplings, tree ferns, and arborescent palms, with an extensive ground cover of pan- dans, sedges, and small ferns. Woody vines, climbing bamboo, and climbing pandans were common, as were strangler figs. Abundant epi- phytes at both sites included pitcher plants, or- chids, and ferns. Leaf litter was extensive, and there was a fairly thick and continuous layer of humus. Site 4 — 4 km N, 21 km E Naga, 1350 m elev., 13°40'N, 123°22'E (12-24 March, 25-30 April 1988). This site had an average slope of ca. 30° and was situated in upper montane forest with a low canopy of 12-20 m. Canopy trees had dbh ranging from 0.3 to more than 0.5 m, with little buttressing. Old logs had heavy moss cover, but moss was uncommon elsewhere on the forest floor. The trunks of all but the youngest trees had moderate moss cover. There was extensive leaf litter and a well-developed humus layer in most areas. Canopy trees had small (2-6 cm) leaves; oaks (Lithocarpus spp.) were common. Understo- ry, vines, and epiphytes were similar to those at Site 3. HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES Fig. 7. Old-growth lowland forest habitat at Site 2, 900 m elevation. March 1988, E. A. Rickart. Fig. 8. Old-growth montane forest habitat at Site 3, 1125 m elevation. March 1988, L. R. Heaney. Site 5^ km N, 21.5 km E Naga, 1550 m elev., 13°40'N, 123°22'E (12-20 March, 19-26 April 1988). This site was in transitional mon- tane-mossy forest in an area with an average slope of 30° and was bounded by steep ravines (Fig. 9). The canopy was at 10-15 m and was broken by many natural treefalls. Canopy trees had dbh of 15-40 cm with no buttressing but of- ten with moderate stilt-root systems; leaves were small (2-6 cm). On steep terrain, lower trunks of trees were sharply inclined. The understory con- sisted of small shrubs, saplings, and tree ferns, with a ground cover of ferns, pandans, orchids, small dicots, and mosses. Climbing bamboo, rat- tan, and particularly climbing pandans were abun- dant. Vascular epiphytes were numerous, includ- ing orchids, ferns, and pitcher plants. Moss was very abundant, reaching depths of 10 cm in some areas but not covering all subcanopy surfaces. At both this and the 1750 m site, there was abundant leaf litter and a deep humus layer. Site 6— A km N, 22 km E Naga, 1750 m elev., 13°40'N, 123°22'E (21-28 March, 20-25 April 1988). This site was situated in well-developed mossy forest (Fig. 10). The terrain was steep, ranging from 30° to 60°. The canopy was at 5-12 m and was broken by numerous treefalls. The largest trees had dbh ranging from 10 to 50 cm. Most trees had elaborate moss-covered stilt-root systems that often exceeded 2 m in basal diameter. Trees growing on the steepest slopes had nearly horizontal main trunks bearing vertical branches that formed the low canopy. Dominant trees in- cluded species of Lauraceae, with small lobate, serrate, or lanceolate leaves, and large, branching tree ferns. All surfaces below the canopy were covered with thick mats of mosses and liverworts. The next phase of fieldwork was conducted on the southern side of Mount Isarog, barangay Del Rosario, Ocampo municipality, from November 1989 to February 1990 by a group led by D. S. Balete. This work was part of an effort to develop a management plan for Mount Isarog National Park. Site 7 — Sitio Guinaban, ca. 100 m elev. (No- vember 1989). We set up one 6-m net for one FIELDIANA: ZOOLOGY Fig. 9. Old-growth transitional montane-mossy for- est habitat at Site 5. 1550 m elevation. 24 April 1988, L. R. Heaney. night in a banana {Musa) plantation for 2 hr and netted a single Eonycteris spelaea. Site 8— Sitio Dos; 4.7 km N, 0.2 km E Ocampo Munic, 300 m elev., 13°36'15"N, 123°23'30"E (19-22 November 1989). This site was an agri- cultural area with a narrow strip of remnant sec- ondary forest along Luksuhon River. Mist nets and snap traps were set in remnant forest and along the edges of abaca and coffee plantations. Agricultural crops included maize, cassava, cof- fee, sweet potato, squash, and coconut. Cultivated trees included jack fruit (Artocarpus heterophyl- la), pili (Canarium luzonicum), star apple (Chry- sophyllum cainito), mango (Mangifera indica), avocado (Persea americana), and guava (Psidium guajava). Forest trees taller than 20 m were rare and consisted mainly of tangid (Cananga odora- ta), rarang (Erythrina subumbrans), lumboy (Sy- zygium spp.), and figs (Ficus spp.). Site 9— Sitio Dos, 5.8 km N, 0.1 km E Ocampo Munic, 500 m elev., 13°36'48"N, 123°23'30"E (22-25 November 1989). This site was a remnant patch of secondary lowland forest on a rocky slope along Luksuhon River. The patch of forest was bounded by grassland with introduced grasses {Imperata cylindrica, Sorghum nitidum, and S. halepense). Netting and trapping sites included a patch of abaca (Musa textilis). Site 10— Sitio Anangi, 5.6 km N, 0.6 km W Ocampo Munic, 475 m elev., 13°36'43"N, 123°23'30"E (18-19 December 1989). The site was within an abaca plantation with very little remaining forest. Here we encountered a dark and spacious cave within a formation of huge rocks on the side of a sloping hill. Trees selectively re- tained to provide shade to abaca consisted mostly of Erythrina subumbrans. Site 1 1— Luktob, 6 km N, 0.9 km W Ocampo Munic, 475 m elev., 13°36'56"N, 123°23'30"E (18-19 December 1989). This site, along the steep bank of Tabuan River, centered on five shallow tunnels that, according to local residents, were dug by retreating Japanese soldiers near the end of World War II. Some tunnels were U-shaped, with both ends opening toward the river, whereas others were dug straight into the steep bank. A narrow strip of lightly disturbed forest surrounded the site. Signs of recent log extraction were evi- dent. Most land above this forested strip was in use for agriculture. Site 12— Pasto, 6.1 km N, 0.3 km W Ocampo Munic, 700 m elev., 13°37'N, 123°23'30"E (27- 29 November 1989). This site included disturbed forest, second-growth vegetation, and cleared pas- ture and agricultural land. Pure stands of moun- tain agoho (Gymnostoma rumphianum) occurred in areas close to Luksuhon River and Tabuan Riv- er. Figs, tree ferns, and rattan were abundant in the forested portion. Disturbed forest with trees up to ca. 20 m in height occurred along the Ta- buan River. We found several large flowers of Rafflesia at this site. Upturned soil on the forest floor indicated that wild pigs were common in this area. A portion of this site, along Luksuhon Creek, said to have been settled originally by the Agta (an ethnically distinct group that tradition- ally engaged in hunting and gathering), remained cleared and was planted with maize, upland rice, and sweet potato. Adjacent to this clearing was a pastureland covered with grass and low stands of guavas. During our survey, half a dozen cattle and several water buffalos were seen grazing here. Site 13— Pasto, 7 km N, 0.1 km W Ocampo Munic, 900 m elev., 13°37'26"N, 123°23'30"E (7-9 December 1989). This site was in a strip of disturbed lowland dipterocarp forest on a ridge HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 11 Fig. 10. Old-growth mossy forest habitat just below the summit of Mount Isarog at ca. 1988, E. A. Rickart. 1900 m elevation. March along the Tabuan River. Mountain agoho was common, especially along trails. Forest canopy was ca. 20 m high. The site was marked with many foot trails used by local people, who regu- larly gather rattan; in 1989-1990, the rattan had been badly depleted. We observed several mature almaciga {Agathis damara) on this site, mostly near the steep bank of the Tabuan River. Site 14 — 7.5 km N, Ocampo Munic, 1100 m elev., 13°37'43"N, 123°23'30"E (10-13 January 1990). This site was in predominantly old-growth forest, with some signs of recent logging, on a ridgetop overlooking the source of the Luksuhon River. The forest, with a canopy height of ca. 25 m, was transitional between lowland and montane types. Few trees had large buttresses. Palms and tree ferns were abundant, and figs also were pres- ent. Rattans, mostly immature because of over- harvesting, were common. Climbing bamboos and pandans were abundant. Several trails cutting through this site were extensions of the ones from Site 1 2 and remained actively used by rattan gath- erers and occasional tree cutters. Site 15—7.9 km N, 0.1 km E Ocampo Munic, 1300 m elev., 13°37'59"N, 123°23'30"E (7-10 January 1990). This site was in old-growth mon- tane forest close to the Tabuan River. The forest canopy height was ca. 25 m, and most of the trees were without buttress roots. Climbing pandans were common. Tree ferns, ground ferns, and palms were abundant. Rattans were common, but there were signs of recent harvesting. Thick moss matted the base of tree trunks and soggy ground. Ephiphytes, including orchids, ferns, and pitcher plants, were abundant. Site 16 — 8.6 km N, 0.6 km E Ocampo Munic, 1500 m elev., 13°38'21"N, 123°23'30"E (7-10 January 1990). This site was in old-growth upper montane forest in a narrow valley. Canopy trees were mostly without buttresses, but stilt roots were not uncommon. The canopy was broken and the forest floor was abundantly covered with leaf litter, mosses, ferns, ground orchids, and herba- ceous plants. Tree ferns, rattans, and climbing pandans were very common. Climbing bamboos were uncommon. Tree trunks and branches usu- ally supported an abundant cover of mosses as well as orchids and ferns. Casts of earthworms were common on the forest floor. Site 17 — 8.9 km N, 0.8 km E Ocampo Munic, 12 FIELDIANA: ZOOLOGY 1700-1800 m elev., 13°38'32"N, 123°23'30"E (31 December 1989-4 January 1990). This site was in mossy forest close to the highest peak on the east side of Mount Isarog. Canopy trees were short, ca. 15 m, and the canopy itself was highly broken. The forest floor was constantly wet and covered with thick leaf litter and matted mosses. Trees with stilt roots were common; those with buttresses were rare. The forest floor vegetation consisted mainly of herbaceous plants, ground or- chids, and ferns. Trees were usually abundantly covered with mosses from trunk to canopy. Climbing pandans were common. Epiphytes con- sisting of dwarf orchids and ferns were abundant. Casts of earthworms were common on the forest floor. Site 18^ km N, 21 km E Naga, 1650 m elev., 13°40'N, 123°22'E (November 1993-May 1994). This was the site for the mark-and-recapture study of small mammals conducted in 1993-1994 by D. S. Balete (Balete, 1995; Balete & Heaney, 1997). Data reported here include summaries of data from Balete and Heaney (1997) as well as more detailed information not published elsewhere. This site lies between Sites 5 and 6 and was gen- erally similar to Site 5 in canopy height and forest structure. Thirty-six tree species, representing 23 families, with a total density of ca. 26 trees/ 100 m2, were recorded within a 1 ha area at this site (Table 1). The canopy was 9-12 m in height, and the trees were thickly covered with mosses and epiphytic orchids and ferns (Huperzia, Selaginel- la, Hymenophyllum, and Trichomanes spp). Climbing pandans were attached to many of the trees. The dominant tree species included Eugenia (= Syzygium) spp. (Myrtaceae), Tricalysia fasci- culata (Rubiaceae), and Elaeocarpus argentes (Elaeocarpaceae). Tree ferns (Cyathea sp.) were also a dominant group. Forest floor vegetation in- cluded many ground ferns (e.g., Dipteris conju- gata) and herbaceous plants (e.g., Languas scabra and Sarcandra glabra). Rattans were also an abundant component of understory vegetation. The density of invertebrates at this site was documented by Balete (1995) from December 1993 to April 1994. Amphipods were the most abundant group, with a mean density of 137 in- dividuals/m2 (range 78-238 individuals), followed by diplopods with 53 individuals/nv (range 30- 88 individuals; Table 2). Biomass (Table 3), how- ever, was highest for earthworms at 3.28 g/m: (range 1.02-6.40 g), followed by amphipods at 1.25 g/m2 (range 1.06-1.66 g). We also have included Rabor's 1961 collection Table 1. Summary of vegetation analysis in the mossy forest on Mt. Isarog. showing the basal area and density (trees/100 m:) of each species sampled. Total basal area Trees/ Species (cm2) 100 m2 Syzygium spp. 28,726.9 4.1 Tricalysia fasciculata 626.6 2.9 Cyathea spp. 918.6 2.6 Elaeocarpus argentes 10,766.9 0.7 Rapanea arvenis 2.208.3 1.6 Weinmannia luzoniensis 5,276.6 0.9 Symplocos modesta 609.3 1.2 Ilex halemenses 4,647.1 0.5 Adinandra elliptica 3,921.8 0.5 Eurya nitida 2.008.6 1.0 Helicia cumingiana 272.6 1.1 Daphnipyllum luzonense 675.4 1.0 Glochiciion rubrum 1,862.2 0.5 Claoxylon brachyandrum 711.9 0.7 Psyclwtria lucida 132.6 0.6 Persea philippinensis 519.0 0.5 Clethra lancifolia 232.1 0.5 Vaccinium spp. 791.1 0.4 Lithocarpus budii 172.1 0.5 Symplocos conchinchinensis 236.6 0.4 Geniostoma ru pest re 56.7 0.4 Plachonella linggensis 434.0 0.3 Symplocos sp. 261.2 0.3 Symplocos cumingiana 799.6 0.2 Macaranga dipterocaprifolia 651.1 0.2 Schima sp. 488.4 0.2 Ilex crenata 136.9 0.2 Melastoma sp. 15.7 0.2 Litsea perottittii 490.4 0.1 Cryptocarya elliptifolia 113.1 0.1 Veronia arborea 132.7 0.1 Eicus septica 50.3 0.1 Astronia williamsii 7.1 0.1 Evodia acuminata 7.1 0.1 Lisianthus chinensis 3.1 0.1 Podocarpus rotundus 19.6 0.1 Rapanea philippinensis 33.2 0.1 Unidentified 1.890.7 0.6 All species 70.827.7 25.7 of mammals from the southwest side of Mount Isarog (Baranggay Curry, Pili Municipality; Ra- bor, 1966). This collection, deposited at several museums in the United States, included the ho- lotypes of two taxa of murid rodents endemic to Mount Isarog: Archboldomys luzonensis and Rhynchomys isarogensis (Musser, 1982b; Musser & Freeman, 1981). However, we have not been able to locate any field catalog or notes pertaining to Rabor's collection other than his subsequent short account of the expedition (Rabor, 1966). Elevational data were taken from the labels of HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 13 Table 2. Density (number/m2) of leaf-litter and soil invertebrates sampled monthly in the mossy forest on Mt. Isarog, 1550 m. Month Class/Order Dec Jan Feb Mar Apr Mean ± SD Annelida 11 29 45 35 28 30 ± 12.4 Crustacea Amphipoda 238 150 111 78 109 137 ± 61.9 Isopoda 32 25 25 18 23 25 ± 5.0 Chilopoda 11 19 17 60 3 22 ± 22.1 Diplopoda 30 47 88 36 62 53 ± 23.2 Arachnida Araneae 17 27 28 23 17 22 ± 5.3 Opiliones 2 5 8 3 0 4 ± 3.0 Pseudoscorpiones 0 0 2 0 0 — Insectaa 74 54 53 14 24 44 ± 24.4 Total 415 356 377 267 266 336 ± 67.0 Samples of Coleoptera, Diptera, Lepidoptera, and unidentified insects include larvae and pupae. specimens deposited in the Field Museum and the American Museum of Natural History. Apparently, Rabor did not make an intensive or systematic survey of small mammals on Mount Isarog. We are therefore unable to make a detailed comparison of the changes in the composition of small mammal communities in the ensuing 20 years, as was done for birds by Goodman and Gonzales (1990). A description of habitats is lack- ing, but we surmise that the vegetation in Rabor's study sites listed below approximated our present study sites at 300-900 m (his Sites 19-22, our Sites 1,2, 12, and 13) and at 1750 m (his Site 23, our Sites 6, 17, and 18) in terms of forest struc- ture. The degree of disturbance to forest at his lowland sites in 1961 was quite likely to have been less severe than that at our sites in 1988— 1995. Locations plotted in Figure 5 are estimates based on elevation and specimen labels that state the localities were "above Curry." Site 19— ca. 450 m (10 April 1961). Site 20— ca. 600 m (12 April 1961). Site 21— ca. 725 m (30 March; 3, 9, and 14 April 1961). Site 22^a. 800 m (7, 15, 23, and 25 April 1961). Site 23— ca. 1700+ m (15, 25-28 April 1961). Methods Our studies in 1988 followed methods used in earlier studies on Leyte, Negros, Catanduanes, and other islands (Heaney et al., 1989, 1991; Table 3. Biomass (mg/m2) of leaf-litter and soil invertebrates sampled monthly in the mossy forest on Mt. Isaroj 1550 m. Weights taken from drained fluid specimens. Month Class/Order Dec Jan Feb Mar Apr Mean ± SD Annelida 1,024 2,155 2,348 6,401 4,461 3,278 ± 2,142.4 Crustacea Amphipoda 1,666 1,277 1,119 1,064 1,175 1,250 ± 240.3 Isopoda 304 265 334 267 307 295 ± 29.3 Chilopoda 149 196 270 60 33 142 ± 97.4 Diplopoda 339 399 541 942 1,027 650 ± 315.8 Arachnida Araneae 162 603 342 314 392 363 ± 159.4 Opiliones 1 33 33 68 0 27 ± 28.1 Insectaa 200 127 481 143 271 243 ± 144.3 Total 3.845 5,055 5,468 9,256 7,666 6,258 ± 2,171.6 Includes all orders listed in Table 2. 14 FIELDIANA: ZOOLOGY Rickart et al., 1991) to facilitate comparisons. Bats were caught in mist nets set on ridgetops, across trails and streams, and at the edges of clearings adjacent to forest. Nets were tended con- tinuously during the old-growth activity peak from early dusk (about 17:30) until about 21:00, and some were tended longer. Nets were left open thereafter, and bats were removed at dawn. Any given net was left in place for 3 or 4 days at a time in all but a few instances. We also captured Megaderma spasma from a roost in a hollow tree using a fragment of a mist net. During 1988, nonvolant small mammals were caught in a mixture of Victor rat traps (ca. 75%) and National live traps (ca. 25%). Traps were bait- ed late each afternoon with fresh fried coconut coated with peanut butter, or with live earth- worms. Traps were checked each morning soon after dawn and late each afternoon, and occasion- ally in the early afternoon and evening. Traps were placed 5-15 m apart; most (95%) were placed on the ground, but ca. 5% were placed aboveground on fallen trees, horizontal branches, or large vines. Traps were left in place for 3-5 days but usually for 4 days. The study conducted in 1989-1990 on the southern side of Mount Isarog (Ocampo Munici- pality) consisted of mist-netting and livetrapping. Mist nets were examined in the late afternoon and at dawn, and occasionally during the evening. We also captured Emballonura alecto in a cave and in several tunnels by setting mist nets at the en- trances. Our record of Pteropus hypomelannus was of an individual shot by a local resident. We employed cage traps constructed from welded wire and baited with roasted coconut coated with peanut butter to capture nonvolant small mam- mals. At Sites 16 and 17, we used dried squid on some of the traps. When we returned to Site 17 in 1992, we used only Victor rat traps baited with earthworms. From November 1993 to May 1994, a capture- mark-recapture study was conducted in the mossy forest at Site 18 (Balete, 1995; Balete & Heaney, 1997). From December 1993 to early February 1994, trapping was done on four 6X6 subgrids with an intertrap distance of 5 m for 4 days every other week using cage traps manufactured from welded wire. From late February to April, the in- tertrap distance was doubled to 10 m. Two types of baits were used: roasted strips of coconut coat- ed with peanut butter during the first 2 days and live earthworms tied to the traps' bait hooks dur- ing the last 2 days. During the final phase, sampling of nonvolant small mammals for stomach content analysis was done at 1500 and 1700 m using Victor rat traps baited with roasted coconut coated with peanut butter during the first 2 days and with live earth- worms during the succeeding 2 days. Tempera- tures were recorded daily with minimum-maxi- mum thermometers that were maintained in shad- ed spots about 1.5 m above the forest floor. Pre- cipitation was measured with a rain gauge placed in a spot below an opening in the canopy. Further details on the methodology of this study were pre- sented by Balete (1995) and Balete and Heaney (1997). Unfortunately, we have no way to ascertain the specific collection techniques used by Rabor's field crews, but they probably included snap traps, mist nets, firearms, and acquisition from local hunters (Goodman & Gonzales, 1990). Voucher specimens were prepared in fluid, as skeletons, or as skins with partial skeletons and have been deposited at the Field Museum, Chi- cago (fmnh), the Natural Science Museum at the Iligan Institute of Technology of Mindanao State University, Iligan City (nsm-iit), the Philippine National Museum, Manila (pnm), University of the Philippines, Los Banos (uplb), and the United States National Museum of Natural History, Washington, D.C. (usnm). Other specimens ex- amined in the course of this study are deposited at the American Museum of Natural History (amnh) and the Florida Museum of Natural His- tory (fsm). In 1988, specimens were necropsied in the field for reproductive information. Size of embryos was measured as crown-rump length (CRL). Subadult animals are defined here as those that have not completed cranial growth, especially those having unfused basicranial sutures. Sub- adults lack adult pelage but are nearly as large as adults, and female subadults are often undergoing their first reproductive activity. Comments on dis- tribution and use of scientific names are based on Heaney et al. (1998) unless stated otherwise. Re- cords of specimens examined, including site num- ber and number of specimens (in parentheses), are summarized at the end of each account. External measurements and weights reported here were taken by the authors in the field on fresh animals in 1988. All cranial measurements were taken by Heaney with digital calipers grad- uated to 0.01 mm. Comparisons of cranial mea- surements that are made in this paper are to pub- lished records of specimens also measured by Heaney. HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 15 •flr *rsa Fig. 11. Adult Crocidura grayi. 29 March 1988, at Site 3. L. R. Heaney. In May 1990, the Wildlife Biology Laboratory at uplb, where most of the specimens collected from the southern slope were deposited, was de- stroyed by fire. All specimens indicated as depos- ited at uplb were lost during that fire and are pre- sented here for the purpose of species accounts. Measurements taken from these specimens are not included in the computation of means and ranges of cranial and external measurements. Instead, such measurements, in the absence of other mea- surements from extant specimens of species from previous or later studies, are indicated in their re- spective species accounts. Accounts of Species Order Insectivora Family Soricidae — Shrews Crocidura grayi Dobson, 1890 Prior to this study, the Luzon white-toothed shrew (Fig. 11) had been reported from Catan- duanes, northern Luzon, and Mindoro (Heaney et al., 1991; Heaney & Ruedi, 1994). This small shrew (10.8 g) was present from 475 m to 1750 m (Fig. 12) in disturbed and old-growth lowland forest and old-growth montane and old-growth mossy forest; it was significantly more abundant in montane forest than elsewhere (Rickart et al., 1991). A closely related species, C. beatus, showed similar patterns of elevational range and abundance on Leyte (Heaney et al., 1989; Rickart et al., 1993). Trap success for this species in 1988 ranged from 0.15% to 1.04% with coconut bait and from 0.29% to 2.91% with live earthworm bait; overall trap success was significantly greater with earthworm bait (x2 = 13.470; P < 0.001). Stomachs of snap-trapped specimens contained fragments of insects and terrestrial amphipods (amphipods were common at high elevations; Ta- bles 2 and 3) but did not contain recognizable plant material (Rickart et al., 1991). This species is best described as a generalist insectivore. Shrews were active both day and night; out of a total of 38 trapped specimens, 15 (39.5%) were taken during daylight hours. Three additional specimens were hand-caught during the day, and several others were sighted as they ran about the 16 FIELDIANA: ZOOLOGY c o > 5 1966 (peak) 1500 1000- 500 ! L— 1 1— p-i J 1 1 [ H i i c D D D D O D 1 1 II 1 D | 0 \ D O i i i i d i □ 7 8 8 5 3 3 SSL £S 2^ 5 in ^ 5 3 5 s: -O 3 P 0Q as 5* -s: bo u p Fig. 12. Elevational distribution of native shrews and murid rodents on Mount Isarog. Numbers in the right column indicate the number of species known to be present at a given elevation and those inferred to be present because they were taken both above and below in the 1988 transect study. Dotted lines indicate the elevation of intensive sampling sites. forest floor. All specimens were taken at the ground surface in areas of moderate to heavy cov- er, most often along runways next to fallen logs or at openings to tunnels along the steep sides of ravines or at the bases of live trees or stumps. The scats of viverrids collected by Balete (1995) did not reveal any indication of predation on this spe- cies (see P. hermaphroditus account, below). Seventeen females were caught in March and April 1988. Of nine adults (10.3 ± 1.87 g) with enlarged mammae, four had a single embryo each and one had two embryos (CRL = 2-8 mm). Av- erage litter size for eight females (based on counts of fetuses or placental scars) was 1.2 ± 0.5 (range, 1-2). Two adult females captured in April 1994 also had enlarged mammae; one had a swol- len reproductive tract and the other had a single embryo (CRL = 7 mm). Testes of most males were abdominal. Testes size of seven adult males (11.1 ± 0.90 g) ranged from 2.5 X 3 mm to 3 X 4 mm. Nine other males of unverified age (9.6 ± 2.60 g) had testes size from 1.5 X 2 mm to 2.5 X 4.5 mm. See Heaney and Ruedi (1994) for cra- nial measurements. Specimens Examined — Total 42. Site 1 (1 pnm); Site 2 (2 usnm); Site 3 (25 usnm); Site 4 (3 usnm); Site 5 (2 usnm); Site 6 (6 usnm); Site 18 (2 fmnh). Suncus murinus (Linnaeus, 1766) Our record of the Asian house shrew, a com- mon non-native species, consisted of a single adult female. It was caught by a house cat in an agricultural area close to second-growth forest, at ca. 325 m, probably within or just outside a house. We trapped none within the forest, despite inten- sive sampling. Total length = 194 mm, tail length = 66 mm, hind foot = 18 mm. Specimens Examined — Total 1 . Site 8 ( 1 uplb). Order Chiroptera Family Pteropodidae — Fruit Bats Cynopterus brachyotis (Midler, 1838) The common short-nosed fruit bat is wide- spread in Southeast Asia and is found on virtually every island in the Philippines, where it is abun- dant in agricultural areas and disturbed forests and often present but usually uncommon in old- growth lowland and montane rain forest (Heaney et al., 1989, 1991; Heideman & Heaney, 1989; HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 17 1966- (peak) 1500- •2 iooo- > S 500- O 1988 transect • other records, 1991-95 i I I 3 -~ — I — M ■3-3 s s u-s: •2-f £< J3 3 3 8*1 o'-B a "FT s* 59 Si J Fig. 13. Elevational distribution of fruit bats on Mount Isarog. Dotted lines indicate the elevation of intensive sampling sites. Ingle, 1992; Lepiten, 1997; Rickart et al., 1993). Utzurrum (1992) considered Philippine popula- tions to be stable or increasing and to be an im- portant contributor to seed dispersal and natural forest regeneration in degraded habitats. This spe- cies is called sabolo by native settlers in Del Ro- sario, who sometimes hunt it for food. An indig- enous contraption consisting of several thorny tips of rattan fronds, ca. 30 cm in length, tied together around one end of a long bamboo pole was used for catching these bats. The pole is used by the hunter to swat the bats attracted to fruiting or flowering trees. Those bats whose wings are caught in the thorny tips of the pole cannot free themselves. Cynopterus brachyotis was abundant in dis- turbed forest at 475 m and in mixed second- growth and old-growth lowland forest at 900 m during our 1988 transect study but was not found at higher elevations (Fig. 13, Table 4). In 1989— Table 4. Abundance and elevational distribution of fruit bats (Pteropodidae) on Mt. Isarog during 1988 field season. Data are from standardized sampling procedures. Sites and elevation (m) 1 2 3 4 5 6 Species 475 900 1125 1350 1550 1750 Cynopterus brachyotis 67 20 0 0 0 0 Haplonycteris fischeri 4 0 0 0 0 0 Harpyionycteris whiteheadi 3 0 0 0 0 0 Macroglossus minimus 7 15 0 0 0 0 Otopteropus cartilagonodus 16 25 5 5 1 1 Ptenochirus jagori 17 18 3 0 0 0 Total species 6 4 2 1 1 1 Total bats 113 76 8 5 1 1 Total net-nights 75 54 56 63 66 26 Species/net-night 0.08 0.07 0.04 0.02 0.02 0.04 Fruit bats/net-night 1.51 1.41 0.14 0.08 0.02 0.04 18 FIELDIANA: ZOOLOGY Fig. 14. Cynopterus brachyotis roosting in a palm leaf that has been modified into a "tent." April 1992, Del Rosario. Ocampo Municipality. D. S. Balete. 1990, along the southern transect, they were com- mon in agricultural areas, second-growth, and dis- turbed forest from 500 to 1 100 m but were absent in old-growth forest at higher elevations where Otopteropus cartilagonodus predominated. Thirteen primiparous females (28 ± 1.6 g) and 18 multiparous females (31 ± 1.9 g) each were pregnant with a single embryo (CRL = 10.4 ± 4.5 mm). Two multiparous females (38 g each) captured in May 1988 were pregnant with single embryos (CRL = 27 and 39 mm). Testes of males netted in March 1988 ranged from 2X3 mm to 5X6 mm. Males with full adult pelage averaged 30.6 g (range = 25-36 g, N = 24), and those with the dull subadult pelage averaged 26.6 g (range = 22-32 g, N = 6). Reproductive patterns in this species were described by Heideman (1995). In an agricultural area at Del Rosario, near Site 8, in April 1992, we observed C. brachyotis roost- ing singly and in groups of up to four individuals in tent roosts constructed from the large circular leaves of anahaw palm (Livistona sp.) in a fashion similar to that described by Utzurrum (1992) for C. brachyotis in Manila and by Rickart et al. (1989) for Scotophilia kuhlii in Quezon City. Two palm trees each had five leaves turned into tent roosts, but most were not occupied when the ob- servation was made. Close examination of the tent roosts revealed that they were all formed by chewing roughly 3-cm segments of almost all of the midribs of the deeply lobed, circular palm leaf. The leaf then drooped from the ends of the chewed parts, forming an umbrella-shaped struc- ture. Chewed midribs formed a circular shape with a radius of ca. 15 cm from the distal end of the leaf petiole (Fig. 14). In December 1993, shortly after a typhoon struck the area, we ob- served two C. brachyotis roosting under the fronds of tree ferns. Measurements are given in Table 5. Cranial variation throughout the Philippines (Biliran, Ca- miguin, Catanduanes, Leyte, Luzon, Maripipi, and Negros) appears to be slight (Heaney, 1984; Hea- ney et al.. 1991; Heaney & Rabor, 1982; Rickart et al.. 1993). and analysis of variation in allo- zymes indicated little genetic variation between Philippine populations (Peterson & Heaney. 1993). Kitchener and Maharadatunkamsi (1991) and Schmitt et al. (1995) have suggested that C. b. luzoniensis from the Philippines and Sulawesi HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG. PHILIPPINES 19 Table 5. Mean (± SD) and range of selected cranial and external measurements of adult fruit bats (Pteropodidae) from Mt. Isarog, southern Luzon, Philippines. Sample size other than N is indicated by the number enclosed in parentheses after the range. Measurements taken from sample sizes of 2 and 3 are given as averages and their ranges. All measurements except weight are in millimeters. Condylo- Inter- Post- basal Zygomatic orbital orbital Mastoid Species Sex N length breadth width width breadth Cynopterus brachyotis M 10 28.4 ± 0.81 18.9 ± 0.65 6.5 ± 0.34 6.5 ± 0.61 12.0 ± 0.44 27.0-29.4 17.7-19.8 6.0-7.0 5.7-7.3 11.4-12.6 F 10 27.9 ± 0.65 18.6 ± 0.40 6.3 ± 0.29 6.5 ± 0.31 11.8 ± 0.39 26.6-29.1 18.0-19.2 5.9-6.6 6.2-7.0 11.1-12.4 Haplonycteris fischeri M 3 23.7 16.4 6.0 6.3 10.6 23.2-24.1 15.8-17.2 5.8-6.2 6.1-6.4 10.4-10.9 F 1 23.4 16.4 5.5 4.9 10.3 Harpyionycteris whiteheadi M 1 40.7 23.8 6.7 6.6 15.1 Macroglossus minimus M 6 24.1 ± 0.54 14.0 ± 0.70 4.7 ± 0.27 7.0 ± 0.30 9.9 ± 0.34 23.2-24.8 13.1-14.6 4.3-5.1 6.6-7.4 9.4-10.3 F 8 24.3 ± 0.65 13.3 ± 0.33 4.6 ± 0.16 7.0 ± 0.17 9.8 ± 0.16 23.3-25.2 12.8-13.6 4.4-4.9 6.7-7.2 9.5-10.0 Otopteropus cartilagonodus M 6 22.3 ± 0.41 15.0 ± 0.56 3.7 ± 0.28 6.2 ± 0.40 10.0 ± 0.12 21.8-22.9 14.2-15.5 3.4-4.1 5.6-6.6 9.9-10.2 F 7 22.4 ± 0.36 15.1 ± 0.31 3.8 ± 0.29 6.4 ± 0.21 10.0 ± 0.23 21.8-22.9 14.6-15.4 3.4-4.2 6.1-6.6 9.7-10.4 Ptenochirus jagori M 7 33.5 ± 1.06 23.8 ± 0.95 7.0 ± 0.49 6.2 ± 0.27 14.2 ± 0.37 32.1-35.1 22.5-25.5 6.6-8.1 5.9-6.6 13.6-14.6 F 10 33.4 ± 0.87 23.5 ± 0.97 6.9 ± 0.38 6.4 ± 0.22 14.3 ± 0.44 32.1-34.9 21.9-24.9 6.2-7.3 6.2-6.8 13.5-14.9 Pteropus hypomelanus F 1 — 33.6 8.4 9.1 19.5 be recognized as a distinct species. However, they included too few localities and specimens to doc- ument the patterns of geographic variation within the Philippines, and we recommend further study before their recommendations are accepted. Specimens Examined — Total 115. Site 1 (17 pnm, 59 usnm); Site 2 (20 usnm); Site 9 (4 uplb); Site 12 (5 uplb); Site 13 (7 uplb); Site 14 (3 uplb). Eonycteris spelaea (Dobson, 1871) The cave-roosting nectar bat is strongly asso- ciated with lowland agricultural areas (Heaney et al. 1989; Heideman & Heaney, 1989). We netted only two specimens, in agricultural areas at 100 and 300 m elevation (Fig. 8) in Ocampo Munic- ipality. Ingle (1992) netted only six among over 1,500 bats captured in lowland forest at 200-500 m elevation on Mount Makiling. Although we found this species to be uncommon on Mount Is- arog, it is believed to have generally stable or in- creasing populations in the Philippines (Utzurrum, 1992), though individuals may be subject to in- tensive human hunting in the caves where they roost (e.g., on Leyte; Rickart et al., 1993). Specimens Examined — Total 2. Site 7(1 uplb); Site 8 (1 uplb). Haplonycteris fischeri Lawrence, 1939 The Philippine pygmy fruit bat, a widespread Philippine endemic, is often common in old- growth forests, especially in montane forest; it is rarely present in agricultural land and is uncom- mon in second-growth forests (Heaney et al., 1989, 1998; Heideman & Heaney, 1989; Rickart et al., 1993). Utzurrum (1992) considered the spe- cies to be widespread and stable in numbers but vulnerable to habitat destruction. We netted only five individuals, all adults, in disturbed lowland forest at the 475 m site and none in old-growth forest at higher elevations (Fig. 13, Table 4). Heaney et al. (1991) found them to be common in lowland forest on Catanduanes, Ingle (1992) captured 14 at 200-500 m elevation on Mount Makiling, Laguna Province, and Ruedas et al. (1994) captured only one, at 1100 m, in Zambales Province, west-cen- tral Luzon. These observations may imply that this species has a lower elevational range in the Greater Luzon area (e.g., Ingle, 1993) than in the central Philippines, where previous studies have 20 FIELDIANA: ZOOLOGY Table 5. Extended. Post- Palatal Rostral Orbital orbital C to Molariform breadth Palatal Total length length length last M tooth row at last M length length 9.2 ± 0.44 12.0 ± 0.39 13.4 ± 0.46 9.6 ± 0.33 6.7 ± 0.23 6.2 ± 0.25 14.4 ± 0.35 100 ± 4.7 8.5-9.7 11.5-12.7 12.6-14.2 8.8-10.1 6.3-7.1 5.8-6.5 13.6-14.8 94-115 (21) 9.0 ± 0.33 11.6 ± 0.37 13.1 ± 0.43 9.6 ± 0.14 6.7 ± 0.16 6.3 ± 0.27 13.9 ± 0.33 100 ± 4.8 8.5-9.5 11.2-12.3 12.5-13.7 9.4-9.9 6.5-7. 1 5.9-6.7 13.3-14.3 92-118 (40) 7.8 9.5 11.9 8.5 6.0 4.9 11.5 71.3 7.5-8.1 9.4-9.8 11.7-12.2 8.3-8.7 5.9-6.1 4.7-5.0 11.3-11.7 70-73 7.7 9.3 11.4 8.2 5.7 4.9 11.2 73 11.4 17.9 15.2 15.6 11.5 7.9 20.1 140 9.0 ± 0.28 7.9 ± 0.33 10.5 ± 0.15 8.3 ± 0.34 5.1 ± 0.23 4.9 ± 0.21 12.8 ± 0.36 70 ± 5.0 8.6-9.3 7.4-8.3 10.3-10.7 7.9-8.8 4.8-5.4 4.6-5.1 12.2-13.3 65-77 9.3 ± 0.41 7.8 ± 0.31 10.2 ± 0.19 8.6 ± 0.26 5.3 ± 0.20 5.1 ± 0.20 13.2 ± 0.37 70 ± 4.1 8.7-9.9 7.4-8.2 9.9-10.4 8.3-9.0 5.0-5.6 4.7-5.3 12.7-13.8 65-77 (9) 7.4 ± 0.27 8.9 ± 0.21 10.6 ± 0.10 7.4 ± 0.17 5.1 ± 0.12 4.7 ± 0.19 11.2 ± 0.39 73 ± 5.4 6.9-7.6 8.6-9.2 10.4-10.7 7.2-7.7 5.0-5.3 4.5-5.0 10.7-11.8 65-79 (9) 7.5 ± 0.29 8.9 ± 0.33 10.9 ± 0.30 7.4 ± 0.14 5.1 ± 0.13 4.9 ± 0.18 1 1.3 rt 0.28 75 ± 4.9 7.1-7.8 8.4-9.3 10.5-11.4 7.1-7.5 4.9-5.3 4.7-5.2 10.8-11.7 66-83 (23) 10.4 ± 0.40 15.1 ± 0.55 15.8 ± 0.52 11.8 ± 0.49 8.4 ± 0.35 7.6 ± 0.22 16.8 ± 0.71 125 ± 7.6 9.9-11.2 14.4-16.1 14.9-16.4 11.3-12.8 8.2-9.0 7.3-8.0 15.8-18.1 113-146(17) 10.2 ± 0.52 15.3 ± 0.57 15.7 ± 0.43 11.6 ± 0.26 8.4 ± 0.22 7.7 ± 0.34 16.8 ± 0.60 126 ± 5.6 9.5-11.0 14.3-16.0 15.1-16.3 11.2-12.0 8.1-8.7 7.2-8.1 15.5-17.7 117-138 (13) 21.6 23.9 — 21.9 16.0 11.8 33.2 — been done (e.g., Heaney et al., 1989; Rickart et al., 1993). This species feeds heavily on the fruits of wild fig trees (Ficus spp.; Utzurrum, 1995). We caught most of our specimens at Site 1 in a lo- cation where fruiting fig trees were abundant in second growth under the canopy of the introduced Leucaena leucocephala. Three males (16-18 g, N = 2) netted in March 1988 had testes measuring 4X4 mm to 5 X 6 mm. A multiparous female (17 g) with enlarged mammae had a single embryo (CRL = 2 mm). This species has delayed development and highly synchronous reproductive cycles within popula- tions (Heideman, 1988, 1989). Cranial measurements (Table 5) are similar to those of series from Biliran, Catanduanes, Dina- gat, Leyte, Luzon, and Negros; cranial geographic variation appears to be slight (Heaney, 1984; Hea- ney & Rabor, 1982; Heaney et al., 1991; Rickart et al., 1993). Genetic geographic variation in the species is substantial and is associated principally with the extent of Pleistocene islands (Peterson & Heaney, 1993). Specimens Examined — Total 5. Site 1 (1 pnm, 4 usnm). Harpyionycteris whiteheadi Thomas, 1 896 The Philippine harpy fruit bat, an endemic spe- cies, was unknown from Luzon Island prior to our study; previous records were from Camiguin. Mindoro, Negros, and several islands of Greater Mindanao (Biliran, Leyte, Maripipi, and Minda- nao; Heaney, 1991; Peterson & Fenton, 1970; Rickart et al., 1993). The three specimens report- ed here constitute the first record from Greater Luzon and formed the basis for the inclusion of this species in the Luzon fauna by Heaney ( 1 99 1 ) and Heaney et al. (1998). The species is common in old-growth mid-elevation forest on Leyte and Negros, occasionally venturing into adjacent sec- ond-growth forest (Heaney et al., 1989; Heideman & Heaney, 1989; Rickart et al., 1993). Utzurrum (1992) considered this species to have stable pop- ulations but to be vulnerable to habitat destruc- tion, and noted that they typically occur in low densities. On the evening of 4 May 1988, we heard the penetrating whistling call of this species along a ridgetop in mixed agricultural land and second growth forest at 475 m (Site 1). We traced the HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 21 Table 5. Extended. Tail Hind Species length foot Ear Forearm Weight (g) Cynopterus brachyotis 7 ± 2.8 16.3 ± 1.3 18 ± 1.2 63 ± 2.8 29.5 ± 2.63 2-12 (21) 13-17 (18) 15-20 (21) 58-70(21) 24.5-35 (21) 8 ± 2.1 16 ± 1.0 18 ± 1.0 62.4 ± 2.02 29.7 ± 2.58 3-12 (39) 13-18 (36) 15-19 (40) 58-68 (40) 25.5-38 (39) Haplonycteris fischeri 0 12.8 14.0 46.3 17.0 — 12-13 13-15 42-50 16-18(2) 0 13 13 50 17 Harpyionycteris whiteheadi 0 23 23 85 102 Macroglossus minimus 0 15 ± 3.0 16 ± 0.8 42 ± 1.5 13.6 ± 0.74 — 12-18 15-17 39-43 12.5-14.5 0 13 ± 2.0 16 ± 0.9 42 ± 0.8 14.8 ± 2.67 — 12-17 (9) 14-17 (9) 41-43 (9) 11.5-21 (9) Otopteropus cartilagonodus 0 13 ± 3.0 13 ± 0.9 48 ± 1.3 16.5 ± 1.59 — 11-19 (9) 12-14 (9) 46-51 (9) 15-20 (9) 0 14 ± 3.0 14 ± 0.7 48.3 ± 1.65 15.9 ± 1.73 — 11-19 (23) 12-15 (23) 44-52 (23) 13-19 (23) Ptenochirus jagori 11 ±2.4 20 ± 1.2 20 ± 1.1 78 ± 3.5 62.9 ± 7.10 6-14 (16) 19-22 (12) 18-23 (17) 72-84 (17) 45-73 (17) 9 ± 2.7 22 ± 0.8 20 ± 0.9 77 ± 3.2 66.5 ± 10.41 4-14 (12) 21-23 (13) 18-21 (13) 73-83 (13) 55-87 (13) Pteropus hypomelanus — — — — — calls to a fruiting pandan vine (Freycinetia sp.) in a large tree, where we saw the bats land and feed on the fruits. On that and the following night we saw many H. whiteheadi feeding on the fruit of the same vine, and we netted three males, an adult (102 g), a subadult (83 g), and a juvenile (77 g). We had heard the calls of this species in the same area in April 1988. The limited available evidence indicates that viney pandans (Freycinetia spp.) form the old-growth food for this species (Utzur- rum, 1995). Reproductive patterns in this species were described by Heideman (1995). Cranial measurements of the single adult male (Table 5) fit well within the range of those from Leyte (Rickart et al., 1993) but are slightly small- er than those of several specimens from Camiguin (Heaney, 1984). Assignment to subspecies as de- fined by Peterson and Fenton (1970) seems am- biguous; geographic variation needs to be reas- sessed. Specimens Examined — Total 3. Site 1 (3 usnm). Macroglossus minimus (E. Goeffroy, 1810) The dagger-toothed flower bat is found from Thailand to Australia (Koopman, 1993); in the Philippines it is abundant in agricultural areas on most islands (Heaney, 1991; Heaney et al., 1998). Utzurrum (1992) considered it to have generally stable or increasing populations in the Philippines. It is found at virtually all elevations where Musa (banana and abaca) is present, though usually in higher density at low than at high elevation (Hea- ney et al., 1989; Heideman & Heaney, 1989; In- gle, 1992; Lepiten, 1997; Rickart et al., 1993). On Mount Isarog, these small bats were com- mon in habitats ranging from 300 to 900 m (Fig. 13) in mixed agricultural land and remnant forest (Sites 8 and 9), disturbed forest adjacent to agri- cultural land (Sites 1 and 12), and mixed old- growth lowland forest and agricultural land (Site 2; Table 4). In most places they were associated with domestic or wild banana. Local farmers and workers in abaca plantations told us that this spe- cies often roosts under dried, drooping leaves of abaca and banana. Eight multiparous (15 ± 3.0 g) and three pri- miparous (13, 14, and 15 g) females netted in March 1988 were pregnant, each with a single embryo (CRL = 8 ± 6.5 mm). Seven adult males weighed 14 ± 0.8 g; three were noted as having abdominal testes (2X3 mm to 7 X 8 mm). Specimens Examined — Total 26. Site 1 (1 pnm, 7 usnm); Site 2 (13 usnm); Site 8 (1 uplb); Site 9 (3 uplb); Site 12 (1 uplb). 22 FIELDIANA: ZOOLOGY Fig. 15. Otopteropus cartilagonodus. 27 March 1988, Site 3. L. R. Heaney. Otopteropus cartilagonodus Kock. 1969 Prior to our 1988 survey, the Luzon pygmy fruit bat (Fig. 15), a poorly known Luzon endem- ic, was reported only from northern Luzon (Hea- ney et al.. 1998; Kock, 1969; Mudar & Allen, 1986). Ingle (1992) took none in over 1,500 bats captured in lowland forest at 200-500 m elevation on Mount Makiling, Laguna Province. Ruedas et al. (1994) reported on specimens from Zambales Province, Luzon, and included those described here. Utzurrum (1992) described this species as having stable populations but being vulnerable to habitat destruction because of the apparent restric- tion to old-growth or lightly disturbed forest. We found this species throughout our netting transects, from 475 m to 1750 m and above (Fig. 13); it was either the most common or the only fruit bat at all sites except Site 1 (475 m), where Cynopterus brachyotis was most common (Table 4). Along the western transect, it was common in mixed secondary and old-growth lowland forest and agricultural land at 475 m and 900 m sites (Table 4) and uncommon at higher elevations. On the southern transect, we found it to be common in old-growth upper montane and transitional montane-mossy forest at 1300-1500 m. As noted by Ruedas et al. (1994), we found males to be proportionately more numerous than females at higher elevations and females to predominate at lower elevations. Seasonal variation in habitat use is unknown. A subadult (14.5 g) and five adult (16.8 ± 2.14 g) females were netted in January 1990 at Site 15. In March 1988, all of the 33 females we netted, consisting of 15 adults (15.6 ± 1.16 g, N = 14), 5 young adults (14.5 ± 1.3 g), and 13 of unde- termined age, each had a single embryo (CRL = 2.5 ± 0.46 mm, N = 31). Each of the four mul- tiparous females (18 ± 1.0 g) netted in May 1988 also had a single but larger embryo (CRL = 14 ± 1.3 mm). Twenty-eight males were netted in December 1989 and January 1990 at Sites 15-17, of which 14 adults weighed 18.0 ± 1.56 g and 2 subadults weighed 13 and 15.5 g. Six adult (17.2 ± 1.57 g) and three young adult (15, 15. and 16.5 g) males captured in March and May had small testes ranging in size from 1 X 2 mm to 3 X 4 mm. On the basis of specimens collected in 1988, Heideman et al. (1993) suggested that this species exhibits highly synchronized annual reproduction and delayed development, a pattern also found in HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG. PHILIPPINES 23 Haplonycteris fischeri (Heideman, 1989). Mea- surements are provided in Table 5 and in Ruedas et al. (1994). Specimens Examined — Total 88. Site 1 (1 fmnh, 2 pnm, 13 usnm); Site 2 (2 pnm, 23 usnm); Site 3 (2 pnm, 5 usnm); Site 4 (1 fmnh, 3 usnm); Site 5 (1 usnm); Site 6 (1 usnm); Site 12 (1 uplb); Site 15 (1 fmnh, 1 iitm, 20 uplb); Site 16 (6 uplb); Site 17 (5 uplb). Ptenochirus jagori (Peters, 1861) The musky fruit bat, an endemic Philippine species, is found throughout the Philippines ex- cept the Palawan and Batanes/Babuyan regions. It is common in old-growth and lightly disturbed forest and sometimes is present in more degraded forest (Heaney et al., 1998; Heideman & Heaney, 1989; Lepiten, 1997; Rickart et al., 1993). It was the most abundant species of fruit bat (80% of 1,430 captures) in lightly disturbed forest at 200- 500 m elevation on Mount Makiling, Laguna Province (Ingle, 1992). These bats feed principal- ly on fruit of wild figs (Ficus spp.; Utzurrum, 1995). Utzurrum (1992) considered them to have generally stable populations but to be vulnerable to habitat destruction because of their dependence on low-elevation rain forest. Along our western transect on Mount Isarog, this species was common in disturbed lowland forest (475 and 900 m), uncommon in lower mon- tane forest at 1125 m, and absent at higher ele- vations (Fig. 13, Table 4). It was found in a great- er range of elevations and habitats along the southern transect, from heavily disturbed lowland forest at 450 to mossy forest at 1750 m, but was most common in lowland and lower montane for- est (Table 4). In January 1990, five individuals of this species were flushed from their roost under a large branch, ca. 15 m above ground, that was covered with epiphytes and a large bird's nest. The roost was found in old-growth montane forest at 1300 m at Site 15. Eleven females (63 ± 7.1 g) were captured in May 1988; each had a single embryo (CRL = 2- 8 mm). Two other pregnant females netted in May were heavier (68 and 87 g) and had larger em- bryos (CRL = 31 and 35 mm). Of 20 males netted in March 1988, 11 adults (65 ± 5.4 g) had larger testes (3X5 mm to 9 X 12 mm) than the 3 young adults (55, 61 and 64 g; testes size: 3 X 3, 4 X 4, 6 X 7 mm) and the 6 subadults (52 ± 3.7 g, testes size: 2X2 mm to 3 X 5 mm). An adult male (63 g) and a young adult male (61 g) cap- tured in May 1988 had testes size of 6 X 8 mm and 6X7 mm, respectively. Reproductive pat- terns in this species were described by Heideman (1995) and Heideman and Powell (1998). Geographic variation in this species is conspic- uous. Cranial measurements of Mount Isarog bats (Table 5) are similar to those of bats from Catan- duanes (Heaney et al., 1991) but are markedly smaller than those of bats from Biliran, Dinagat, Leyte, Maripipi, and Negros (Heaney & Rabor, 1982; Rickart et al., 1993); bats from Camiguin appear to be intermediate (Heaney, 1984). Specimens Examined — Total 82. Site 1(12 pnm, 22 usnm); Site 2 (4 pnm, 15 usnm); Site 3 (3 usnm); Site 9 (4 uplb); Site 12 (1 uplb); Site 13 (11 uplb); Site 15 (6 uplb); Site 16 (3 uplb); Site 17 (1 uplb). Pteropus hypomelanus Temminck, 1853 The common island flying fox is distributed from the Maldive Islands to the Solomon Islands (Koopman, 1993) and is found through most of the Philippines, where it is common in lowland agricultural areas and often hunted for food (Hea- ney et al., 1998; Rickart et al., 1993). Utzurrum (1992) considered this species to have declined substantially in the Philippines in recent years but to be the least endangered of the Philippine flying foxes because of its wide range and the presence of populations in some protected areas. Our only record of this species on Mount Isarog was a young adult female (261 g, forearm =121 mm) shot by a local hunter in December 1989 among fruiting fig trees (Ficus spp.) in an agri- cultural area in Del Rosario at 400 m near Site 8; measurements are provided in Table 5. A single flying fox sighted on 5 March 1988 as it flew overhead at dusk may also have been this species. It is called sabulaw (= golden) by local hunters in reference to its golden mantle. Hunters in this area also described to one of us (D. S. Balete) at least two other flying foxes, which are reported below under P. leucopterus and P. vampyrus. Two more large bats known to the hunters as paluy- puyon and tarungan were present; we suspect that these may be Acerodon jubatus and Pteropus pumilus, but further data are required to verify this identification. Specimens Examined — Total 1. Site 8 (1 uplb). 24 FIELDIANA: ZOOLOGY Pteropus leucopterus Temminck, 1853 The mottle-winged flying fox is a poorly known endemic species recorded only from Ca- tanduanes (Heaney et al., 1991), Dinagat, and Lu- zon (Heaney & Rabor, 1982). Utzurrum (1992) considered the species to have declined substan- tially in recent years and to be in need of protec- tion. Although we captured none of these bats on Mount Isarog, reports from knowledgeable and apparently reliable local hunters lead us to believe that they are present. These hunters reported a bat they called angaspa and described it as larger than P. hypomelanus but with white wings. The hunt- ers stated that these white-winged bats were par- ticularly fond of feeding on the flowers of rarang, Erythrina subumbrans, when this tree begins to bloom, typically in February. It is said to be very aggressive and tends to drive away other flying foxes trying to feed on the same tree. Pteropus vampyrus (Linnaeus, 1758) The large flying fox occurs from Indochina to the Lesser Sunda Islands (Koopman, 1989, 1993). It is widespread in the Philippines (excluding the Batanes/Babuyan region), although it is inten- sively hunted in many areas and has declined sub- stantially in numbers (Utzurrum, 1992). A single specimen of this species was taken by the Rabor team on 23 April 1961; no elevation was noted, but other specimens taken on the same date were from ca. 800 m (Site 22). We neither saw nor captured any in 1988-1990, but in 1989- 1990 local hunters on Mount Isarog reported to us a very large black bat, much larger than P. hypomelanus, which they called dulom (meaning pitch dark, as the ambient light during a new moon). This report seems to agree with the ap- pearance of the common melanistic morph of P. vampyrus. These reports indicate that this species may have been present in low numbers during our studies. Specimens Examined — Total 1. Pili, barangay Curry (1 amnh). Rousettus ample xicaudatus (E. Geoffroy, 1810) The common rousette ranges from Thailand to the Solomon Islands (Koopman, 1989, 1993). In most areas of the Philippines, it is among the most abundant species in agricultural areas, despite be- ing hunted in the caves where it roosts (Heaney et al., 1989; Utzurrum, 1992). It is also sometimes present, but usually quite uncommon, in old- growth forest (Heideman & Heaney, 1989; Lepi- ten, 1995; Rickart et al., 1993). In November 1989, we netted two females, an adult with en- larged mammae (85.7 g) and a young adult (82.2 g), in heavily disturbed forest at ca. 500 m (Site 9) and 675 m (Site 12). Specimens Examined — Total 2. Site 9 (1 uplb), Site 12 (1 uplb). Family Emballonuridae — Sheath-tailed bats Emballonura alecto (Eydoux and Gervais, 1863) The Philippine sheath-tailed bat is known from Borneo and Sulawesi (Koopman, 1989, 1993) and is found virtually throughout the Philippines (Heaney et al., 1998). We captured two adult males in December 1987 in dimly lit areas in a shallow cave along Anangi Creek at 475 m (Site 10) in an abaca plantation with no intact forest around it. A few days later we captured four males and six females from a group of ca. 25 individuals inside a shallow tunnel along the Ta- buan River in an area of mixed secondary forest and agricultural land at 475 m (Site 11). These sites are similar to the small caves surrounded by disturbed forest where these bats have been found on Catanduanes (Heaney et al., 1991), Leyte, and Maripipi (Rickart et al., 1993) and on Mount Makiling, Laguna Province, Luzon (Ingle, 1992). In December 1989, all of the six males (5.9 ± 0.38 g) we netted had abdominal testes, and five (5.9 ± 0.22 g) of the six adult females had en- larged mammae. Two additional specimens were captured at Site 11 on 11 April 1994: a male (5 g) with undes- cended testes and a pregnant female (8 g) with a single embryo (CRL = 20 mm). The number of bats during this visit to the tunnel along the Ta- buan River appeared to have increased to about 50 from the ca. 25 bats observed during our visit in December 1989. Two other caves along this river, which were uninhabited by this species in 1989, had small colonies of ca. 10-15 bats in April 1994. Measurements are given in Table 6. Specimens Examined — Total 14. Site 10 (2 uplb); Site 11 (2 fmnh; 10 uplb). HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 25 Table 6. Mean (± SD) and range of selected cranial and external measurements of adult microbats (Emballonuri- dae, Megadermatidae, and Rhinolophidae) from Mt. Isarog, southern Luzon, Philippines. Sample size smaller than N is indicated by the number enclosed in parentheses after the range. Measurements taken from sample size of 2 are given as averages and their ranges. All measurements except weight are in millimeters. Condylo- Inter- Condylo- incisive Zygomatic orbital caninc Mastoid Species Sex N length breadth width length breadth Emballonura alecto M 1 13.4 8.8 2.8 12.9 7.6 F 1 13.8 9.1 2.9 13.2 7.8 Megaderma spasma M 2 — 14.4 3.4 23.0 11.6 — 14.4-14.5 3.3-3.4 22.7-23.4 11.6 F 2 23.4 — 3.8 22.8 11.5 23.2-23.7 14.9 (1) 3.8-3.9 22.4-23.1 11.4-11.6 Hipposideros bicolor3 M 1 16.2 8.8 2.6 15.2 9.0 Hipposideros diadema F 3 25.6 16.6 3.4 25.7 13.8 25.3-26.0 16.3-17.1 3.3-3.6 25.5-26.0 13.7-13.9 Hipposideros obscurus M 1 16.4 10.9 2.3 16.3 9.6 Hipposideros pygmaeus Mb 5 12.3 ± 0.22 6.8 ± 0.13 2.0 ± 0.07 11.7 ± 0.34 6.9 ± 0.10 12.3-12.4 6.8-6.9 1.9-2.0 11.7-12.0 6.9-7.0 Rhinolophus arcuatus- 1 M 3 18.6 9.7 1.9 17.8 9.5 18.3-19.0 9.4-9.9 1.8-2.0 17.6-18.0 9.2-9.7 F 2 18.3 9.2 2.0 17.8 9.2 17.8-18.8 9.0-9.4 1.8-2.1 17.6-18.0 9.1-9.4 Rhinolophus inops M 3 22.9 12.0 2.1 17.4 11.3 22.6-23.1 11.7-12.2 2.0-2.2 17.3-17.5 11.2-11.3 a External measurements taken on alcohol specimen. b Includes two individuals of undetermined sex. Family Megadermatidae — False vampire bats Megaderma spasma (Linnaeus, 1758) The common Asian ghost bat (or lesser false vampire bat) is a widespread species found from India to the Molucca Islands (Koopman, 1989, 1993); it occurs throughout the Philippines, ex- cept on the Batanes and Babuyan islands (Heaney et al., 1998). We netted individuals in old-growth and disturbed lowland forest at 475 and 900 m (Sites 1 and 2; Fig. 16); most other Philippine records are from lowland forest, although these bats occasionally are found in montane forest (Heaney et al., 1991; Lepiten, 1997; Rickart et al., 1993). Additionally, in March 1988 we found a colony of two females and three males roosting inside a hollow in a large strangler fig (Ficus sp.) in a clearing near Site 2 at ca. 800 m, less than 1 km away from disturbed old-growth forest. One female had large mammae, and both were preg- nant with one embryo each of 12 mm and 14 mm CRL. Adult males had scrotal testes of 2 X 3 mm to 5 X 6 mm. Cranial measurements of Mount Isarog speci- mens (Table 6) are nearly identical to those of bats from Catanduanes (Heaney et al., 1991) and Din- agat (Heaney & Rabor, 1982) but are slightly larg- er than those of specimens from Biliran, Leyte (Rickart et al., 1993), and Mindanao (Heaney & Rabor, 1982). Females appear to be consistently larger than males (Table 6; see also Heaney & Rabor, 1982; Heaney et al., 1991; Rickart et al., 1993). Specimens Examined — Total 9. Site 1 (3 usnm); Site 2 (6 usnm). Family Rhinolophidae — Horseshoe-nosed Bats Hipposideros bicolor (Temminck, 1834) The bicolored roundleaf bat has been recorded from India to Timor (Koopman, 1989, 1993); in the Philippines it is known from Luzon, Mindoro, and Palawan (Heaney et al., 1998). A single spec- imen (Table 6), taken on an unknown date near Pasacao on the Ragay Gulf coast ca. 40 km south- west of Mount Isarog (13°32'N, 123°03'E), is the sole record of this species in southern Luzon; Ruedas et al. (1994) reported one from Zambales Province in central Luzon. We captured none on Mount Isarog but suspect that this species once 26 FIELDIANA: ZOOLOGY Table 6. Extended. Palatal Rostral Orbital CI to Molariform breadth Palatal Total length length last M tooth row at last M length length 3.3 5.6 5.4 3.9 3.3 4.8 57 3.4 5.5 5.6 4.1 3.3 4.8 63 5.2 7.8 9.1 7.0 3.6 6.9 74 ± 4.79 5.2 7.8 8.9-9.3 6.9-7.2 3.5-3.6 6.7-7.1 70-80 (4) 5.4 8.0 9.2 7.2 3.7 6.8 72 5.3-5.5 7.9-8.1 8.9-9.4 7.1-7.3 3.6-3.8 6.5-7.1 71-72 4.8 5.8 5.8 4.6 3.6 6.1 — 5.3 9.4 10.8 8.2 7.4 9.9 141 5.2-5.5 9.2-9.7 10.4-10.7 7.9-8.4 7.2-7.7 9.7-10.1 137-148 3.5 6.7 6.4 5.1 5.3 5.6 72 4.0 ± 0.14 3.9 ± 0.08 4.6 ± 0.09 3.6 ± 0.04 2.8 ± 0.15 4.2 ± 0.21 — 3.8-4.1 3.9-4.0 4.5-4.7 3.6-3.7 2.7-3.1 3.9-4.4 — 5.2 7.5 5.5 4.1 6.1 76 5.1-5.3 7.4-7.7 5.4-5.6 4.0-4.2 5.9-6.2 75-78 — 5.0 7.2 5.4 4.0 5.9 74 5.0-5.1 7.2-7.3 5.4-5.5 3.0-4.0 5.7-6.1 72-76 — 6.4 9.2 6.6 5.2 7.7 89 6.3-6.5 9.1-9.3 6.5-6.6 5.2-5.3 7.5-7.9 85-93 occurred within current park boundaries. Mea- surements are given in Table 6. Specimens Examined — Total 1. Pasacao (1 usnm). Hipposideros diadema (E. Geoffroy, 1813) The diadem roundleaf bat is widespread in Indo-Australia (Koopman, 1984, 1989, 1993); it is found throughout the Philippines except in the Batanes/Babuyan region (Heaney et al., 1998). It appears to be most common in lowland areas, in both heavily disturbed and old-growth forest (In- gle, 1992; Lepiten, 1995; Rickart et al., 1993). We netted three adult females in disturbed lowland forest at 475 m (Site 1). Two pregnant females, weighing 31 and 50 g, each had a single embryo (CRL = 6 and 30 mm, respectively). Specimens Examined — Total 3. Site 1 (3 usnm). mossy forest at 740 m on Maripipi, and Heaney et al. (1991) captured several in old-growth low- land forest at 250 m elevation on Catanduanes Island, one of which was roosting in a hollow log. Ingle (1992) found them in lightly disturbed low- land forest at 200-500 m elevation on Mount Makiling, Laguna Province. Lepiten (1995) found them in heavily disturbed lowland forest at 550 m elevation on Siquijor. We captured a single adult male (10 g) in disturbed forest at 475 m (Site 1; Fig. 16, Table 7). Cranial measurements of the Mount Isarog specimen (Table 6) are similar to those of bats from Catanduanes (Heaney et al., 1991) and are slightly larger than those of a specimen from Din- agat (Heaney & Rabor, 1982) and a series from Maripipi (Rickart et al., 1993), indicating that sig- nificant geographic variation may occur in this species. Specimens Examined — Total 1. Site 1 (1 usnm). Hipposideros obscurus (Peters, 1861) Hipposideros pygmaeus (Waterhouse, 1843) The Philippine forest roundleaf bat is a poorly known endemic species previously recorded from Greater Luzon, Greater Mindanao, and Greater Negros-Panay (Heaney et al., 1991, 1998; Rickart et al., 1993). Rickart et al. (1993) reported it from disturbed lowland forest at 600 m and old-growth The Philippine pygmy roundleaf bat is a poorly known endemic; it has been reported from Greater Luzon, Greater Mindanao, and Greater Negros- Panay (Heaney et al., 1998). We did not capture this species on Mount Isarog, but three adult male and two adult female specimens (Table 6) were HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 27 Table 6. Extended. Tail Species length Hind foot Ear Forearm Weight (g) Emballonura alecto 9 6 13 47 5 10 8 15 48 8 Megaderma spasma 0 20 ± 0.6 38 ± 1.5 58 ± 1.5 22.0 ± 0.82 — 18-20 36-39 57-60 21-23 0 19 40 59 25.0 — 18-20 38-41 58-60 24.5-25.5 Hipposideros bicolor* 31 8 20 42 Hipposideros diadema 47 18 29 81 39.7 45-50 17-19 28-30 78-83 31-50 Hipposideros obscurus 20 12 18 44 10 Hipposideros pygmaeus — — — — — Rhinolophus arcuatus- 1 21 11 23 46 8.5 20-23 10-12 22-24 45-48 8-9 21 11 21 44 12.5 20-22 11 21 44-45 8-17 Rhinolophus inops 26 13 27 55 17 25-27 13 26-27 55 15-18 1966 (peak) 1500 •2 k as > w --Q-- 1 □ 1988 standardized sampling • other records 1 x inferred 1 - * 1 n""l --□--■ 1 4 x. x....n....n..-.n -D — 6 - 1 [ 1- 1 i—o i t ) ~o— 6 --•-H ]— □— Q-— 1 1 Cr \ y—i I Q- 9 500- —i 5S "a 55 ^ &3 I' S3 &a •5 -s* a is a a ss, J -a -sis p:? §-a -3-s « i W >, fe C P ft. ex, on Fig. 16. Elevational distribution of insectivorous bats on Mount Isarog. Numbers in the right column indicate the number of species known to be present at a given elevation and those inferred to be present because they were taken transect study. Dotted lines indicate the elevation of intensive sampling sites. both above and below in the 28 FIELDIANA: ZOOLOGY Table 7. Abundance and elevational distribution of insectivorous bats on Mt. Isarog. Site and elevation (m) 1 2 3 4 5 6 Species 475 900 1125 1350 1550 1750 Megaderma spasma 2 1 0 0 0 0 Hipposideros diadema 3 0 0 0 0 0 Hipposideros obscurus 1 0 0 0 0 0 Rhinolophus arcuatusA 1 2 0 1 0 0 Rhinolophus inops 0 3 0 0 0 0 Kerivoula hardwickii 0 0 0 1 0 0 Harpiocephalus harpia 1 0 0 0 0 0 Murina cyclotis 2 0 1 0 0 0 Myotis muricola 0 0 2 0 0 0 Myotis rufopictus 0 0 1 0 0 0 Philetor brachypterus 1 0 0 0 0 0 Pipistrellus javanicus 0 2 3 31 18 3 Total species 7 4 4 3 1 1 Total bats 11 8 7 33 18 3 Total net-nights 75 54 56 63 66 26 Bats/net-night 0.15 0.15 0.12 0.52 0.27 0.12 Species/net-night 0.09 0.07 0.07 0.05 0.02 0.04 collected on an unknown date near Pasacao, where H. bicolor also was taken (see previous ac- count); it should be sought in the area. All known records of this seemingly rare species are associ- ated with caves in or near forest. Measurements are given in Table 6. Specimens Examined — Total 1. Pasacao (5 usnm). Rhinolophus arcuatus Peters, 1871 As currently defined, this species occurs from Sumatra to New Guinea (Koopman, 1989, 1993), probably including the entire Philippines. How- ever, at least two species are currently suspected to be included under this specific epithet in the Philippines: a slightly smaller species, designated "/?. arcuatus-s" associated with lowland caves, and a slightly larger species, "/?. arcuatus-X" as- sociated with upland old-growth forest (Heaney et al., 1991, 1998; Ingle & Heaney, 1992). We netted three males and two females on Mount Isarog, in secondary lowland forest at 475 m, disturbed lowland forest at 900 m, and upper montane forest at 1350 m (Sites 1, 2, and 4; Fig. 16), all in March 1988. One of the males was captured while it foraged on fireflies (Lampyri- dae) over a partly cleared ridgetop adjacent to old- growth dipterocarp forest. Their habitat prefer- ence and cranial and external measurements sug- gest their close affinity to the R. arcuatus-X mor- photype. One adult female (17 g) had a single embryo (CRL = 6 mm), and the other was nul- liparous (8.5 g). Two of the males (8 and 8.5 g) had abdominal testes. Cranial measurements (Table 6) are slightly smaller than those of specimens from Catandu- anes and Negros (Heaney et al., 1991; Ingle & Heaney, 1992; specimens in usnm). Specimens Examined — Total 5. Site 1 (1 usnm); Site 2 (2 usnm); Site 4 (2 usnm). Rhinolophus inops Andersen, 1905 The Philippine forest horseshoe bat is a poorly known endemic reported previously from Greater Luzon, Greater Mindanao, Mindoro, and Greater Negros-Panay (Heaney et al., 1991, 1998; Rickart et al., 1993: specimens in usnm). On Biliran and Leyte, it was the most common microchiropteran encountered at most sites in old-growth lowland, montane, and mossy forest (Rickart et al., 1993). Heaney et al. (1991) encountered many in a cave in heavily disturbed lowland forest at 80 m ele- vation on Catanduanes. On Mount Isarog it was less common; we captured only three adult males (15-18 g) in a ridgetop clearing in old-growth dipterocarp forest at 900 m (Site 2). Cranial measurements (Table 6) are larger than those of the series from Catanduanes, Luzon, and Negros (Heaney et al., 1991; specimens in usnm). Specimens Examined — Total 3. Site 2 (3 usnm). HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 29 Table 8. Mean (± SD) and range of selected cranial and external measurements of adult microbats (Vespertilioni- dae) from Mt. Isarog, southern Luzon, Philippines. Sample size smaller than N is indicated by the number enclosed in parentheses after the range. Measurements taken from sample size of 2 are given as averages and their ranges. All measurements except weight are in millimeters. Condylo- Inter- Condylo- incisive Zygomatic orbital canine Mastoid Species Sex N length breadth width length breadth Harpiocephalus harpia M 1 20.3 13.6 5.5 19.7 11.3 Kerivoula hardwickii F 1 12.8 8.1 2.9 12.1 7.3 Miniopterus schreibersi M 1 14.6 8.4 3.8 13.5 8.3 Murina cyclotis F 2 17.4 11.1 4.8 16.6 9.2 17.4-17.5 11.1 4.7-4.9 16.5-16.8 9.2-9.3 Myotis muricola M 1 13.8 (9.4) 3.6 12.8 7.7 F 1 14.0 9.3 3.5 12.9 7.6 Myotis rufopictus F 1 17.0 11.8 4.5 15.9 9.1 Philetor brachypterus M 1 — — — — — Pipistrellus javanicus M 10 13.4 ± 0.21 9.3 ± 0.21 3.8 ± 0.13 12.7 ± 0.23 8.1 ± 0.19 13.2-13.9 9.1-9.8 3.6-4.0 12.4-13.2 7.8-8.3 F 6 13.5 ± 0.19 9.3 ± 0.32 3.7 ± 0.14 12.7 ± 0.15 8.0 ± 0.19 13.2-13.7 8.8-9.6 3.5-3.9 12.5-12.9 7.8-8.3 Family Vespertilionidae — Common bats Harpiocephalus harpia (Temminck, 1840) The hairy-winged bat is widespread in Asia, from India to the Moluccas (Koopman, 1989, 1993); its occurrence in the Philippines was pre- viously documented on Leyte, Negros, and Panay (Heaney et al., 1993, 1998; Utzurrum, unpubl. data). One adult male (15 g) was captured in dis- turbed lowland dipterocarp forest at 475 m (Site 1). This was the first record of this species on Luzon and was referred to by Ingle and Heaney (1992) and Heaney et al. (1998). An additional record from Luzon was reported by Ingle (1993). Measurements are given in Table 8. Specimens Examined — Total 1. Site 1 (1 usnm). Kerivoula hardwickii (Horsfield, 1824) The common woolly bat is widespread from In- dia and southern China to the Lesser Sunda Is- lands (Koopman, 1989, 1993); in the Philippines it was previously recorded only on Greater Min- danao (Leyte, Mindanao, and Samar) and Palawan (Heaney et al., 1998; Rickart et al., 1993). In March 1988, we captured a single specimen of this species, a pregnant female (5 g) with a single embryo (CRL = 8 mm), in upper montane forest at 1350 m (Site 4; Table 7). Rickart et al. (1993) noted two specimens from old-growth lowland forest at 500 m and old-growth ridgetop mossy forest at 950 m on Leyte. Cranial measurements are given in Table 8. Specimens Examined — Total 1. Site 4 (1 usnm). Miniopterus schreibersi (Kuhl, 1819) The common bent-wing bat occurs from Africa through Europe to the Solomon Islands and Aus- tralia (Koopman, 1984, 1989, 1993); it is found throughout the Philippines, where it is common and usually dependent on caves (Heaney et al., 1991, 1998; Rickart et al., 1993). In December 1989, two adult males were captured with an in- sect net while they were apparently pursuing in- sects attracted by the bright fluorescent lights of a building at 1450 m (Site 16; Fig. 16). In a shallow tunnel along the Tabuan River, 475 m elevation (Site 1 1), we collected a decomposing specimen of undetermined sex on the tunnel floor in 1989. There were ca. 25 E. alecto roosting in this tunnel, but we were not able to collect other specimens of M. schreibersi. Balete returned to the same site in April 1994 and found that it sup- ported a colony of ca. 50 bats, but only E. alecto was seen. Measurements are given in Table 8. Specimens Examined — Total 3. Site 11 (1 fmnh); Site 16 (2 uplb). Murina cyclotis Dobson, 1872 The round-eared tube-nosed bat is widespread in southern Asia (Koopman, 1989, 1993) but was 30 FIELDIANA: ZOOLOGY Table 8. Extended. Palatal Rostral Orbital Molariform breadth Palatal Total length length CI to last M tooth row at last M length length 5.5 7.6 7.0 5.0 4.0 9.7 113 3.9 3.5 5.6 3.5 2.6 6.8 78 4.3 4.8 6.0 4.3 3.7 6.3 4.6 6.4 6.2 5.2 3.6 8.1 99 4.5-4.7 6.4 6.2-6.3 5.1-5.2 3.4-3.7 8.1 98-101 4.2 4.8 5.4 4.1 3.1 6.3 92 4.0 4.9 5.6 4.0 3.0 6.1 83 4.8 6.5 7.1 5.4 3.8 8.4 115 102 86 ± 2.6 3.3 ±0.13 5.2 ± 0.21 5.0 ±0.16 3.8 ± 0.14 3.3 ±0.16 4.8 ± 0.31 3.2-3.6 4.9-5.6 4.9-5.3 3.6-4.1 3.1-3.6 4.5-5.5 81-91 (20) 3.5 ±0.15 5.1 ± 0.18 5.0 ±0.16 3.9 ± 0.08 3.2 ±0.11 5.0 ± 0.17 87 ± 2.7 3.3-3.7 4.8-5.3 4.8-5.2 (6) 3.8-4.0 (6) 3.0-3.3 (6) 4.9-5.3 83-91 known previously in the Philippines from single specimens from Biliran, Camiguin, Catanduanes, Luzon, Mindanao, Sibuyan, and Siquijor (Heaney et al., 1991, 1998; Lepiten, 1997; Rickart et al., 1993); two additional specimens from Zambales Province were taken in lightly disturbed montane forest at 1100 m and 1500 m (Ruedas et al., 1994). We netted two females in disturbed low- land dipterocarp forest at 475 m (Site 1), and an- other female was taken in old-growth montane forest at 1125 m (Site 3; Fig. 16). The specimen from Biliran was netted in partially logged low- land forest at 700 m (Rickart et al., 1993); the one from Catanduanes was netted in disturbed low- land forest along a river at 200 m (Heaney et al., 1991), and one from Siquijor was netted in heavi- ly disturbed lowland forest at 550 m (Lepiten, 1995). Two females (1 1 and 13 g) netted in April 1988 were pregnant with two embryos each (CRL = 15-16 mm). A lactating multiparous female ( 1 1 g) caught in May 1988 was not pregnant. Cranial measurements are given in Table 8. Specimens Examined — Total 3. Site 1 (2 usnm); Site 3 (1 usnm). Myotis muricola (Gray, 1846) The whiskered myotis, found from Afghanistan to New Guinea (Koopman, 1993), has been re- corded throughout the Philippines (Heaney et al., 1998). On Leyte, specimens were netted in dis- turbed and old-growth lowland forest at 50 m and 500 m, respectively; at 50 m. 700 m, and 850 m in forest plantation, disturbed lowland forest, and old-growth montane forest, respectively, on Bilir- an; and near sea level in a village on Maripipi Island (Rickart et al., 1993). Ruedas et al. (1994) reported two at 1 100 m and 20 at 1500 m in light- ly disturbed montane forest in Zambales Province, and Ingle (1992) captured several in lightly dis- turbed forest at 200-500 m elevation on Mount Makiling, Laguna Province. On Mount Isarog, we captured two specimens in old-growth montane forest at 1125 m (Site 3), an adult male (6.7 g) and an adult female (8 g) with a single embryo ( 10 mm CRL). Measurements are given in Table 8. Specimens Examined — Total 2. Site 3 (2 usnm). Myotis rufopictus (Hodgson, 1835) The orange-fingered myotis is a Philippine en- demic known only from Luzon (Mudar & Allen, 1986; Taylor, 1934), Negros, Palawan (Allen, 1922), and Sibuyan (Heaney et al., 1998). In March 1988 we captured an adult nulliparous fe- male (9.7 g) in lower montane forest at 1125 m (Site 3; Table 7). The specimen from northeastern Luzon was taken over a stream in old-growth low- land forest at 50 m (Mudar & Allen, 1986). Mea- surements are given in Table 8. Specimens Examined — Total 1. Site 3 (1 usnm). Philetor brachypterus (Temminck. 1 840) The short-winged brown bat occurs from Nepal to New Guinea (Koopman, 1993), with previous HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 31 w PIvL 1 Table 8. Extended. Tail Species length Hind foot Ear Forearm Weight (g) Harpiocephalus karpia 47 12 17 48 15 Kerivoula hardwickii 38 9 14 33 5 Miniopterus schreibersi — — — — — Murina cyclotis 40 11 16 39 11 38-42 10-12 16-17 39 11 Myotis muricola 35 11 14 35 6.7 35 11 15 37 8 Myotis rufopictus 53 11 19 49 9.7 Philetor brachypterus 38 11 12 38 11.8 Pipistrellus javanicus 34 ± 1.5 9 ± 0.6 12 ± 0.2 3^ \ ± 0.9 7.1 ± 0.55 32-38 (20) 8-10 (20) 12-13 (20) 32- -36 (20) 6.5-8 (19) 35 ± 1.7 9 ± 0.5 12 ± 0.7 35.5 ± 0.79 7.0 ± 0.69 33-38 (9) 9-10 (7) 11-13 (9) 34- -36.5 (9) 6-8(9) Philippine records from Catanduanes, Leyte, Min- danao, and Negros (Heaney et al., 1998; Rickart et al., 1993). The Leyte specimen was netted at 500 m in old-growth lowland forest (Rickart et al., 1993). In March 1988 we captured an adult male (11.8 g) with scrotal testes (3.5 X 7 mm) along a roadside in mixed secondary lowland for- est and agricultural land at 475 m (Site 1). Al- though these were the first records from Luzon, Ingle (1992) reported two additional specimens netted in lightly disturbed lowland forest at 200- 500 m on Mount Makiling, Laguna Province, demonstrating their broader distribution on Lu- zon. Measurements are given in Table 8. Specimens Examined — Total 1. Site 1 (1 usnm). Of the 39 males captured, 15 were adults (7.0 ± 0.52 g, N = 14) with scrotal testes ranging from 1 X 2 mm to 3 X 4 mm. Eleven other males (6.6 + 0.38 g) had abdominal testes; two of these had testes sizes of 1 X 3 mm and 2X3 mm. None of the adult females (7.0 ± 0.69 g, N = 9) dis- played detectable reproductive activity. In January 1994, two of three males netted at Site 18 had scrotal testes measuring 3X4 mm and 4X5 mm. The third had abdominal testes. Measure- ments are given in Table 8. Specimens Examined — Total 60. Site 2 (2 usnm); Site 3 (3 usnm); Site 4 (31 usnm); Site 5 (18 usnm); Site 6 (3 usnm); Site 18 (3 fmnh). Pipistrellus javanicus (Gray, 1838) The Javan pipistrelle is found from Korea to Java (Koopman, 1993) and occurs throughout the Philippines (Heaney et al., 1998). It was the most frequently netted microchiropteran on Mount Is- arog. We captured 39 males and 18 females along the western transect in 1988 (Table 7). They were not captured in disturbed lowland forest at 475 m (Site 1), were uncommon in lowland and lower montane forest at 900 m (Site 2) and 1 125 m (Site 3), were abundant in montane and transitional montane-mossy forest at 1350 m (Site 4) and 1550 m (Site 5), and were uncommon in mossy forest at 1750 m (Site 6; Fig. 16, Table 7). Ingle (1992) found them to be moderately common in lightly disturbed lowland forest at 200-500 m el- evation on Mount Makiling, Laguna Province. Order Primates Family Cercopithecidae — Monkeys Macaca fascicularis (Raffles, 1821) The long-tailed macaque occurs from Burma to Timor and is found throughout the Philippines (Fooden, 1991, 1995). In 1988, we saw or heard the calls of this species at all sampling sites except 1750 m (Site 6), but densities were quite low and the animals were very wary. During our study on the southern side of Mount Isarog from November 1989 to February 1990, we encountered only one individual, in secondary lowland forest at 700 m (Site 14). According to local residents, monkeys were ac- 32 FIELDIANA: ZOOLOGY tively hunted within the park prior to and during our field studies. We obtained an adult in March 1988 that had been captured as a pet about 1 year before on the lower western slopes of Mount Is- arog. Two male juveniles kept as pets were seen in barangay Del Rosario, at 300 m elevation (Site 8) on the south side of Mount Isarog. At the same locality, two lower mandibles of recently killed and eaten macaques, a subadult (judging from the presence of some milk teeth and unerupted per- manent teeth) and an adult, were acquired from a local resident. Specimens Examined — Total 3. Unknown ele- vation (2 fmnh, lower mandibles only; 1 usnm). Order Rodentia Family Muridae — Rats and mice Apomys microdon Hollister, 1931 The small Luzon forest mouse (Fig. 17) is en- demic to the Luzon region and currently is known only from Catanduanes Island, Mount Isarog, and the Sierra Madre of northern Luzon (Danielsen et ah, 1994; Heaney et al., 1991; Musser & Heaney, 1992; Rickart et al., 1991). It is easily distin- guished from the sympatric A. musculus by its larger size (total length 226-256 vs. 188-213 mm; basioccipital length 25.1-27.4 vs. 23.4-24.7 mm; Table 9). During 1988, seven adult specimens of this me- dium-sized species (35.1 ± 3.7 g) were taken at elevations ranging from 475 to 1550 m in dis- turbed lowland forest, old-growth montane forest, and mossy forest (Rickart et al., 1991; Fig. 12). The study in 1993-1994 at Site 18 recorded no individuals of this species between 1650 and 1700 m (Balete, 1995). All specimens collected in 1988 were taken at night in traps baited with coconut and set on the ground in areas of heavy cover (0.07-0.33% trap success; Table 2 in Rickart et al., 1991). Stomach contents of three snap-trapped specimens included remains of larval and adult insects as well as seed fragments. The species is probably best described as an insectivore/omni- vore. All three specimens taken at Site 1 (475 m) were caught at the base of large ferns. One female (42 g) taken in early March was pregnant with three embryos (CRL = 21 mm), and one (33.5 g) caught in late April had two recent placental scars. Two adult males (24 and 35 g) taken in March and one adult male (34 g) trapped in April had testes ranging from 3X8 mm to 4 X 7 mm. Measurements are given in Table 9. Specimens Examined — Total 7. Site 1 (3 usnm); Site 3 (1 usnm); Site 4 (1 usnm); Site 5 (2 usnm). Apomys musculus Miller, 1911 The least Luzon forest mouse (Fig. 17) is known only from Dinagat, Luzon, and Mindoro islands (Heaney et al., 1998; Musser, 1982a). Specimens of this small mouse (21.2 ± 1.8 g) were trapped from 1125 to 1750 m in old-growth montane and mossy forest and were significantly more common in montane forest (Rickart et al., 1991; Fig. 12). Trap success ranged from 0.09% to 1.09% per trap-night with coconut bait and from 0.21% to 0.73% per trap-night with live earthworm bait; there was no significant differ- ence in overall bait attractiveness (x2 = 0.008, P > 0.9). At Site 1 8, this was the most commonly trapped species, accounting for 62% of the total number of individuals captured. The mean density of A. musculus (8.8 individuals/ha) was the highest among rodents in the mossy forest, whereas its biomass (163.2 g/ha) was the second lowest (Ta- ble 10). Mean distance moved (MDM) between captures was 42 m (±42.3 m), and intersex dif- ference in MDM was significant (t = -0.583, P > 0.05). Maximum distance traveled between captures ranged from 150 to 190 m among males and from 191 to 226 m among females. Individual home range size of 15 mice (9 males and 6 fe- males) was estimated to be about 0.22 ha (range 0.01-0.56 ha), with home ranges of males (0.15 ha) averaging about half that of females (0.32 ha). Between 20% and 100% of the home range of any given individual overlapped with the home range of a conspecific (Balete, 1995; Balete & Heaney, 1997). Stomach contents of four snap-trapped speci- mens included remains of insect larvae (Diptera, Coleoptera) and fragments of seeds. A captive in- dividual readily accepted several types of fruit, young sedge leaves, coconut bait, peanuts, sweet potato, insect larvae, adult beetles, cicada, har- vestmen, and raw meat. Earthworms, millipedes, adult ants, cockroaches, and a tree fern "fiddle head" were accepted when the animal was hun- gry, but the items listed first appeared to be pre- ferred. The captive mouse rejected some seeds HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 33 Table 9. Mean (± SD) and range of selected cranial and external measurements of adult murid rodents (Muridae) from Mt. Isarog, southern Luzon, Philippines. Sample size smaller than N is indicated by the number enclosed in parentheses after the range. Measurements taken from sample sizes of 2 and 3 are given as averages and their ranges. All measurements except weight are in millimeters. Species Sex N Basioc- cipital length Inter- orbital width Zygomatic breadth Mastoid breadth Apomys microdon M Apomys musculus M 10 Archboldomys luzonensis M Batomys granti M Chrotomys gonzalesi M 26.0 4.6 13.8 12.0 25.1-26.8 (2) 4.4-4.9 (2) 13.4-14.3 (2) 11.7-12.3 (2) 26.3 ± 0.80 4.6 ± 0.10 14.3 ± 0.48 12.1 ± 0.28 25.5-27.4 4.5-4.7 13.6-14.7 11.8-12.4 24.2 ± 0.33 4.3 ± 0.13 13.2 ± 0.22 11.2 ± 0.22 23.7-24.7 4.1-4.5 12.9-13.6 (7) 11.0-11.5 23.8 ± 0.34 4.2 ± 0.10 13.1 ± 0.16 11.2 ± 0.26 23.4-24.4 4.1-4.4 12.8-13.3 10.8-11.5 25.6 ± 0.64 5.4 ± 0.14 13.3 ± 0.11 11.7 ± 0.08 24.7-26.1 5.2-5.6 13.2-13.4 11.6-11.8 25.2 5.6 13.4 11.8 25.0-25.5 5.5-5.6 13.4-13.5 11.7-11.8 40.6 5.7 ± 0.05 22.5 ± 0.53 15.6 40.1-41.1 (3) 5.6-5.7 21.9-23.1 15.4-15.8 (3) 39.2 6.0 20.5 (1) 15.2 37.6-40.7 5.9-6.0 — 14.7-15.6 — 7.7 21.4 17.1 (1) 7.6-7.8 21.3-22.4 — 38.0 7.5 20.0 16.3 36.8-38.6 7.1-7.7 18.8-20.8 15.8-16.7 Fig. 17. Adult Apomys microdon, Apomys musculus, and Batomys granti (top to bottom), showing the relative size and proportions of these species. April 1988, Site 4, L. R. Heaney. 34 FIELDIANA: ZOOLOGY Table 9. Extended. Anterior Maxillary Palatal Nasal nasal Rostral Rostral Orbital molariform breadth Diastema length width depth length length tooth row at P4 length 10.3 3.1 5.7 10.4 9.5 5.3 5.7 6.6 10.0-10.7 2.9-3.4 5.6-5.8 10.0-10.9 9.2-9.8 5.2-5.4 5.6-5.8 6.3-7.1 10.2 ± 0.45 3.2 ± 0.10 5.8 ± 0.13 10.7 ± 0.22 9.9 ± 0.14 5.3 ±0.13 5.7 ± 0.17 7.0 ± 0.24 9.7-10.8 3.0-3.3 5.7-6.0 10.0-11.0 9.8-10.1 5.2-5.5 5.5-5.9 6.3-7.3 9.2 ± 0.42 2.8 ± 0.19 5.4 ± 0.14 9.2 ± 0.28 9.2 ± 0.19 4.8 ± 0.11 5.4 ± 0.12 6.4 ± 0.20 8.5-9.8 2.5-3.0 5.3-5.8 8.8-9.8 9.0-9.5 4.6-4.9 5.2-5.5 6.1-6.8 9.0 ± 0.35 2.6 ± 0.13 5.3 ± 0.11 9.0 ± 0.28 9.2 ± 0.16 4.7 ± 0.11 5.2 ±0.13 6.3 ± 0.18 8.3-9.4 2.4-2.8 5.1-5.4 8.4-9.3 8.9-9.4 4.5-4.8 5.0-5.4 6.0-6.8 9.6 ± 0.32 2.9 ± 0.08 5.1 ± 0.19 10.6 ± 0.42 9.0 ± 0.21 4.6 ± 0.15 5.8 ± 0.10 6.8 ± 0.25 9.3-9.4 2.8-3.0 4.9-5.3 10.1-11.1 8.8-9.3 4.4-4.8 5.7-5.9 6.5-7.1 9.6 3.1 5.1 10.5 8.9 4.7 5.8 6.9 9.2-9.9 3.1 5.1 10.3-10.7 8.8-9.0 4.7 5.8-5.9 6.7-7.1 16.4 ± 0.76 5.0 ± 0.47 9.5 ± 0.14 17.7 ± 1.11 13.9 ± 0.53 8.4 ± 0.42 8.0 ± 0.40 1 1 .4 ± 0.66 15.7-17.4 4.4-5.4 9.4-9.7 16.2-18.8 13.5-14.7 7.9-8.8 7.6-8.5 10.8-12.3 15.8 (1) 5.0(1) 9.4 16.5 (1) 13.4 8.4 7.9 11.0 — — 8.7-10.2 — 13.0-13.7 8.3-8.4 7.7-8.1 10.0-11.9 12.8 (1) 3.8(1) 7.7(1) 14.4 (1) 13.8 6.2 7.4 15.4(1) — — — — 13.4-14.2 6.1-6.3 7.4-7.5 — 12.2 3.7 7.2 13.1 12.8 6.0 6.9 13.9 12.1-12.3 3.4-3.9 6.9-7.6 12.7-13.3 12.1-13.4 5.9-6.2 6.7-7.0 13.2-14.3 and seedlings, some kinds of fruit, the root of a ginger plant, a hard-shelled larva, tender young leaves, a mushroom, moss, large ants, rove bee- tles, caterpillars, and a longhorn beetle. Remains of possible food items collected along runways where this species was captured at Site 18 (Balete, 1995) included the shell of an unidentified land snail, acorns of Lithocarpus sp. (Fagaceae), and seeds of Languas scabra (Zingiberaceae). A fruit of Schima sp. (Theaceae) that apparently had been gnawed by an Apomys, judging from the fine teeth marks, was found in a tree fork ca. 5 m above ground at the same site. All of these plant species are common in forest at Sites 5, 6, and 18 (Table 1). This species is best described as an omnivore. All specimens recorded in 1988 (during a rel- atively dry period) were taken at night, primarily along surface runways in areas of moderate to heavy cover. At Site 18, 11 individuals (23%) were captured between midday and 16:00 (Balete, 1995) during a season of generally heavy rain. Many individuals were caught in tree root com- plexes, at openings to tunnels along the sides of steep ravines, and beside or beneath fallen logs. Two animals were taken in traps set on top of fallen logs (one of which was more than 1 m above the ground), indicating that they are some- what scansorial. A Crocidura grayi was captured in a trap (in a runway beneath a small log) that had caught an A. musculus the previous day. Scats of viverrids collected in the mossy forest at Site 18, 1550-1600 m, contained remains of this spe- cies (Table 12). Two adult females (22 and 23 g) caught in late April 1988 each had two embryos (CRL = 9 and 20 mm). Litter size was 2.0, based on counts of embryos and uterine scars in four females. Adult and young adult males taken in March and April were reproductively active. Seven adults (20.7 ± 1.82 g) and two young adults (18 and 20 g) had scrotal testes ranging in size from 4X6 mm to 5X11 mm. Two immature animals caught in late March and late April weighed 10 and 14.5 g. At Site 1 8, males and females began to exhibit signs of reproductive activity (scrotal testes, perforate vaginas, enlarged mammae) in March (Balete, 1995). None of the females, however, was preg- nant when the study was concluded in May 1994. Two males first captured and marked in January 1994 as subadults (15 and 15.5 g, with dark, soft fur and abdominal testes) were recaptured in March with descended testes and weighing 17.5 and 18.5 g. In addition, a female (15 g) first cap- tured in February with an imperforate vagina was recaptured in mid-March weighing 15.5 g and with a perforate vagina. These are indications that HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 35 Table 9. Extended. Total Tail Species length length Hind foot Ear Weight (g) Apomys microdon 238 134 27 17 31 226-256 125-145 25-28 17-18 24-35 238 ± 12.3 131 ± 3.4 27 ± 1.0 17 ± 0.5 35.4 ± 4.71 227-254 128-136 26-28 16-17 31-42 Apomys musculus 205 ± 8.8 112 ± 4.7 24 ± 0.4 16 ± 0.7 20.4 ± 1.73 188-211 (8) 102-118 (9) 23-24 (11) 15-17 (11) 18-23 (11) 209 ± 4.9 116 ± 3.4 24 ± 0.7 15 ± 0.7 21.8 ± 1.70 200-213 (7) 112-121 (9) 23-25 (9) 15-17 (9) 19-24 (9) A rchboldomys luzonensis 178 ± 8.0 72 ± 6.7 28 ± 0.9 16.8 ± 0.65 35.3 ± 3.21 167-190 (7) 60-80 (8) 26-29 (8) 16-18 (8) 31-41 (9) 176 ± 4.3 72 ± 3.9 27 ± 1.1 17 ± 1.1 36.9 ± 6.80 170-180 (4) 67-76 (5) 26-29 (5) 15-18 (5) 28.5-46.5 Batomys granti 340 144 37 ± 1.5 21.3 173 ± 8.8 331-355 (3) 140-149 (3) 35-38 (5) 21-22 (3) 160-200 (5) 327 ± 16.4 145 ± 16.1 37 ± 1.5 20 ± 0.5 158 ± 16.6 315-356 (5) 128-171 (5) 35-39 (5) 20-21 (4) 135-175 (4) Chrotomys gonzalesi 272 ± 25.5 99 ± 8.2 37 ± 1.9 22 ± 1.1 146 ± 37.9 232-293 (5) 87-105 (5) 34-39 (5) 20-23 (5) 98-190 (5) 250 ± 14.2 91 ± 6.3 36 ± 1.0 21 ± 1.0 106 ± 29.7 230-260 (4) 83-97 (4) 34-36 (4) 20-22 (4) 70-142 (4) individuals of this species becomes reproductively active within their first year as they achieve adult weight. The mean weight of all animals captured and released in 1993-1994 increased steadily from 17.4 g (±1.97, N = 10) in December 1993 to 18.7 g (±1.41, N = 13) in April 1994 (Fig. 18) as the population shifted from an equal mixture of adults and subadults (in December) to nearly all adults in April (Fig. 19). This shift was accom- panied by a shift from virtually no reproductive activity in December to increasing evidence of re- productive capacity (though no pregnancies) in April (Fig. 20). Table 10. Mean density and biomass (± SD) of nonvolant small mammals in mossy forest on Mt. Isarog. From Balete and Heaney, 1998. Species Density (individ- uals/ha) Biomass (g/ha) Apomys musculus 8.8 ± 0.66 163.2 ± 21.20 Archboldomys luzonensis 4.5 ± 1.63 138.5 ± 50.04 Batomys granti 3.0 ± 0.67 591.5 ± 116.49 Rattus everetti 1.2 ± 0.05 333.3 ± 61.37 Rhynchomys isarogensis 2.6 ± 1.05 328.4 ± 113.36 All species 20.1 1554.9 Cranial and external measurements are given in Table 9. Specimens of this species from Mount Isarog have a standard karyotype of 2n = 42, FN = 52, and exhibit chromosomal similarities to both Chrotomys and Rhynchomys (Rickart & Musser, 1993). Specimens Examined — Total 36. Site 3 (3 usnm); Site 4 (17 usnm); Site 5 (3 usnm); Site 6 (1 usnm); Site 18 (8 fmnh); Curry (4 fmnh). Archboldomys luzonensis Musser, 1982 The Mount Isarog shrew-mouse (Fig. 21) is perhaps the most distinctive element of the moun- tain's mammal fauna. This genus and species was described based on a single specimen from 2400 ft. elevation (= ca. 750 m) on Mount Isarog cap- tured by D. S. Rabor's field crew in 1961 (Musser, 1982b). Heaney et al. (1998) listed the species as vulnerable because of its highly limited distribu- tion. A second species of Archboldomys from northern Luzon was described recently (Rickart et al., 1998). In 1988 we captured eight specimens of this small mouse (35.4 ± 5.4 g) in old-growth mon- tane forest at 1350 m and in old-growth mossy forest at 1750 m elevation (Fig. 12; Table 1 in 36 FIELDIANA: ZOOLOGY Fig. 18. Weight of all Apomys musculus livetrapped in mossy forest on Mount Isarog from December 1993 to April 1994, showing average progressive weight gain (from Balete, 1995). Rickart et al., 1991). Six more specimens were captured in mossy forest at 1700-1800 m eleva- tion at Site 17 in 1992. Balete (1995) estimated the density of this species at Site 18 to be 4.5 individuals/ha (±1.63), second only to Apomys musculus (Table 10), but its biomass, 138 g/ha (±50.0 g/ha), was the lowest among the non volant small mammals in mossy forest (Table 10). We consider the species to be moderately common in mossy forest, rare in montane forest, and absent elsewhere. All individuals captured in 1988 were taken in traps baited with coconut (0.22-0.47% trap suc- cess). However, the positions of snap-trapped an- imals suggested that they were not attracted to the bait but rather had accidentally triggered traps set in runways; three animals taken alive were caught by the tail or a hind leg. All six specimens cap- Fig. 19. Age structure of Apomys musculus in mossy forest on Mount Isarog from December 1993 to April 1994 (from Balete, 1995). HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 37 100 Nonreproductive Reproductive Dec Jan I 1993 I Feb Mar 1994 Fig. 20. Reproductive condition of Apomys musculus in mossy forest on Mount Isarog from December 1993 to April 1994 (from Balete, 1995). Fig. 21. Adult Archboldomys luzonensis. March 1988. Site 4, E. A. Rickart. 38 FIELDIANA: ZOOLOGY tured in 1992 were taken in snap traps baited with earthworms (6.00% trap success). Data on move- ments were meager; one female was recaptured within 2 days of its initial capture and 92 m from the initial point of capture (Balete, 1995; Balete & Heaney, 1997). Stomachs of four snap-trapped individuals in- cluded remains of larval insects (Diptera), adult insects (Diptera, Orthoptera, Coleoptera), terres- trial amphipods, and earthworms, all of which were abundant in the area of Sites 5, 6, and 18 (Tables 3 and 4). None contained identifiable plant material. One captive individual readily ac- cepted several kinds of earthworms, live adult flies, and an adult weevil. Fresh rat flesh and dried meat were accepted less avidly, and all types of plant material were rejected. This species is best described as a generalist insectivore. The Mount Isarog shrew-mouse is primarily if not exclusively diurnal. Seven of the eight ani- mals captured in 1988 (87.5%) were trapped dur- ing daylight hours, and one was taken near dawn. In the 1993-1994 study, Balete (1995) recorded two individuals foraging in the mossy forest dur- ing daylight. All specimens were caught on the ground in areas of heavy cover. Most were taken in traps set along well-defined runways, either un- der logs or root tangles or beneath mixed masses of vines, small live plants, and dead vegetation. The chunky body, short limbs and tail, small ears, and short, dense pelage indicate that A. luzonensis probably is semifossorial. Scats of viverrid carnivores collected in the mossy forest at other sites did not yield evidence of predation on this species (Balete, 1995; Table 12). Five adult females were trapped in late March and late April, three of which had two pairs of enlarged mammae. Two pregnant females (37 and 47.5 g) each had a single embryo (CRL = 14 and 17 mm). Two adult males (33 and 35 g) taken during the same period had scrotal testes of 3 X 6 mm and 6X11 mm. A female collected in January 1994 also had enlarged mammae; its re- productive tract showed signs of swelling (Balete, 1995). Cranial and external measurements appear in Table 9. Archboldomys has a karyotype of 2n = 26, FN = 43 that is distinctive; both sexes possess heteromorphic sex chromosomes (Rickart & Mus- ser, 1993; Rickart et al., 1998). Specimens Examined — Total 17. Site 4 (3 usnm); Site 6 (5 usnm), holotype (1 fmnh); Site 17 (3 fmnh, 3 pnm); Site 18 (2 fmnh). Batomys granti Thomas, 1895 The Luzon hairy-tailed rat (Fig. 17) previously was known only from Mount Data in the Central Cordillera of northern Luzon (Musser & Heaney, 1992; Musser et al., 1998). In 1988, we trapped 13 individuals of this medium-sized rat (177.8 ± 20.3 g) in upper montane and mossy forest from 1350 to 1750 m (Fig. 12), and Balete caught a single specimen in mossy forest at 1800 m in 1990. They were significantly more common in mossy forest than in other habitats (Table 1 in Rickart et al., 1991). Trap success in 1988 ranged from 0.07% to 0.47% per trap-night with coconut bait and from 0% to 0.24% per trap-night with earthworm bait, with no significant difference in overall bait attractiveness (x2 = 0.203; P > 0.5). Many animals apparently were caught accidental- ly by traps set in their well-defined runways rather than because of bait attraction. In 1993-1994, live-trapped B. granti were taken in significantly higher frequency with coconut bait (Balete, 1995). The one specimen from the southern transect (Site 17) was taken in a trap baited with dried squid, but it too may have been an accidental capture. Mean density of B. granti estimated in the mark-and-recapture study in 1993-1994 was 3.0 individuals/ha (±0.67), third behind Apomys mus- culus and Archboldomys luzonensis. In contrast, its biomass of 591 .5 g/ha (±1 16.40) was the high- est of all rodents (Table 10). Data on the move- ment of this species were very limited; one female trapped five times on three successive days had a mean distance moved of 11 m (range 5-14 m), and another female captured eight times in 3 months had a mean distance moved of 44 m (±23.0 m, range 14-85 m). The latter female was estimated to have a home range of 0.1 1 ha (Bal- ete, 1995; Balete & Heaney, 1997). The stomachs of snap-trapped specimens all contained finely masticated vegetable material (seeds and leaves) with no trace of chitin or other animal matter. A captive animal avidly accepted small dicot seeds that were sprouting on the forest floor at the upper elevations at the time of our study in 1988. Only the cotyledons were eaten; the sprouts were removed and rejected. Several other potential food items, including earthworms, insects, and various plant matter, also were re- jected. Clearly, this species is a granivore/frugi- vore. All specimens were caught at night. Most were trapped in runways along the sides of ravines or on the ground in steep terrain in areas of moderate HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 39 to heavy cover, sometimes in places where they had climbed through lattices of roots, branches, and moss that extended well above solid ground. In contrast to the two other predominantly noc- turnal species (Apomys musculus and Rattus eve- retti), the scats of viverrids did not reveal evi- dence of predation on this species (Table 12). There was no evidence of reproductive activity during either field period. Nulliparous females (128 ± 32.8 g) with small nipples were taken in late March and late April. Two females (175 and 220 g) taken in late April had old placental scars (three and four) but were not lactating. Two adult males (160 and 175 g) caught in late April had abdominal, inactive testes of 7 X 13 mm and 12 X 22 mm, and another two males (176 and 200 g) had scrotal testes, one of which had a testes size of 7 X 12 mm. None of the individuals marked and recaptured at Site 18 from December 1993 until May 1994 showed signs of reproduc- tive activity (Balete, 1995). In the closely related B. salomonseni, Rickart et al. (1993) encountered no evidence of breeding during the dry season (March and April) on Leyte or Biliran, although they also encountered large juveniles during this season. These data suggest that most reproduction in these two species takes place during the early rainy season, from June to August. Measurements are provided in Table 9. Speci- mens from Mount Isarog have a karyotype of 2n = 52, FN = 52, consisting entirely of telocentric chromosomes. The standard karyotype is indistin- guishable from that of Batomys salomonseni from the Mindanao Faunal Region (Rickart & Musser, 1993; Musser et al., 1998). Specimens Examined — Total 15. Site 4 (1 usnm); Site 5 (6 usnm); Site 6 (6 usnm); Site 17 (1 fmnh); Site 18 (1 fmnh). Bullimus luzonicus (Thomas, 1895) The large Luzon forest rat is a Luzon endemic (Heaney et al., 1998; Musser & Heaney, 1992). The only record from southern Luzon is a series at the Florida Museum of Natural History from the vicinity of Caramoan (13°47'N, 123°51'E), ca. 50 km east of Mount Isarog. These specimens were taken in 1982-1983 from an area of mixed old-growth and disturbed lowland dipterocarp for- est with abundant bamboo, below 300 m elevation in a region dominated by karst (Auffenberg, 1988; Wilkins, pers. comm.). If the species occurs on Mount Isarog, it is probably confined to areas of remnant forest below 900 m elevation. Specimens Examined — Total 6. Near Caramoan (6 fsm). Chrotomys gonzalesi Rickart and Heaney, 1991 The Isarog striped shrew-rat (Fig. 22) is a strik- ingly colored, medium-sized (140.2 ± 36.3 g) an- imal known only from Mount Isarog. It is repre- sented by eight specimens trapped in 1988 (Rick- art & Heaney, 1991; Rickart et al., 1991) in upper montane forest at 1350 m elevation and in mossy forest at 1750 m elevation (Sites 4 and 6; Fig. 12) and two taken in 1992 in mossy forest at 1800 m (Site 17). Three individuals were livetrapped and tagged in the mossy forest at 1550 m (N = 1) and 1650 m (N = 2) within a period of 5 months at Site 18 in 1993-1994. The mark-recapture study at Site 18 obtained so few data on this species that density, biomass, and home range size could not be estimated (Balete & Heaney, 1997). Scats of viverrids collected at 1150-1600 m did not contain remains of this species (Table 12). In 1988, six animals were caught in traps baited with earthworms (three at each site, 0.66% and 0.88% trap success), and two were caught with coconut bait at 1350 m (0.15% success); the greater success with earthworm bait is significant (X2 = 8.232; P < 0.005; Rickart et al., 1991). All three rats captured and released in 1993-1994 were taken with earthworm bait. Stomachs of five snap-trapped animals contained remains of earth- worms, terrestrial amphipods, insect larvae (Co- leoptera, Diptera), adult insects (Orthoptera, Dip- tera), and spiders, all of which are abundant in the area of Sites 5, 6, and 18 (Tables 2 and 3). No traces of plant material were noted. This species is best described as a vermivore/insectivore. Individuals of this species were active both day and night; of eight specimens captured in 1988, three (37.5%) were caught during daylight hours, another at dusk, and the rest at night. All speci- mens were taken in traps set on the ground sur- face in areas of heavy cover. Most individuals were caught in runways beside fallen logs or in subsurface openings among exposed tree roots. The basic morphology (stout body, short strong limbs, stout tail, and large forefeet with strong claws) indicates a semifossorial mode of life. An adult female (111 g) trapped in late March 1988 had prominent teats and five placental scars (probably two sets), and another adult (100 g) 40 FIELDIANA: ZOOLOGY Fig. 22. Adult Chrotomys gonzalesi. 28 April 1988, Site 3, L. R. Heaney. taken in late April was pregnant with two embry- os (CRL = 5 mm). Two adult males (160 g and 190 g) in breeding condition were caught during both months. Both had scrotal testes of 12 X 25 mm and both had visibly convoluted epididymi- des. Two young adult males (115 g and 165 g) taken in March 1988 were likewise approaching breeding condition, both having scrotal testes (7 X 20 mm and 14 X 19 mm) and visibly convo- luted epididymides. Measurements are given in Table 9. Rickart and Heaney (1991) provided additional measurements as well as comparisons with other species of Chrotomys and Celaenomys. The standard karyo- type (only female specimens were examined) is 2n = 44, FN = 52; this is indistinguishable from the standard karyotype of female Rhynchomys (Rickart & Musser, 1993). Specimens Examined — Total 10. Site 4 (5 usnm including holotype); Site 6 (3 usnm); Site 17 (1 fmnh, 1 pnm). Mus musculus Waterhouse, 1843 The house mouse is a widespread commensal species in Southeast Asia and is abundant in Phil- ippine urban areas (Heaney et al., 1998). An adult male and female were hand-caught in an open field newly planted with maize at ca. 350 m (Site 8). Both were inside a dry, empty coconut with a small hole on one end that served as the entrance. The male (10.5 g) had scrotal testes, and the fe- male (9.5 g) had enlarged mammae. Another sub- adult female was trapped in an agricultural field immediately adjacent to a house at 475 m (Site 1). Specimens Examined — Total 3. Site 1 (1 usnm); Site 8 (2 uplb). Phloeomys cumingi Waterhouse, 1839 The bugkun (or southern Luzon giant cloud rat; Fig. 23) is endemic to Catanduanes, Marinduque, and the southern part of Luzon (Heaney et al., 1991; Musser & Heaney, 1992), perhaps as far north as the mountains east of Manila (Oliver et al., 1993a). Populations have declined significant- ly in recent decades because of intense hunting and habitat destruction (Heaney & Utzurrum, 1991; Oliver et al., 1993a), but they remain com- mon in some areas (Heaney et al.. 1991, 1998). HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 41 Fig. 23. Adult Phloeomys cumingi. 5 March 1988, Site 1, L. R. Heaney. This is one of the largest murid rodents; adults may weigh more than 2 kg. In 1988, 11 specimens were obtained from lo- cal hunters in the Mount Isarog region. All were captured at sites between 200 and 500 m elevation in areas of disturbed forest along the Yabo River, a small river that flows down the western flank of the mountain. These remnant forest patches were confined to steep slopes near the river and were surrounded by agricultural land. Two lactating fe- males (each weighing 1.85 kg) with a single nurs- ing young each (370 and 610 g) were obtained on 2 and 4 March, and a postlactating female (1.85 kg) with a juvenile male (1.1 kg) was brought to us on 9 March. An adult male (2.05 kg) was ob- tained on 6 March. Heaney et al. (1991) reported comparable weights for adult females (1.45-2.1 kg), nulliparous females (1.14-1.15 kg), nursing young (480 and 665 g), old adult males (1.74 and 1.95 kg), and a young adult male (1.45 kg) from Catanduanes. The first female/young pair was found in a hol- low space in a large strangler fig tree, the second in a standing live hollow tree that they entered through a hole ca. 4 m aboveground, and the third in a standing, hollow dead tree (dbh ca. 35 cm). The adult male was captured as the sole occupant of a hollow standing tree. All were located by a dog and were forced to leave the tree because of smoke from a fire built at the base of the tree. In February 1994, a viverrid scat collected in old-growth forest, ca. 1150 m, contained foot bones of an adult of this species (Table 12). This is the first recorded case of predation on this spe- cies, although scavenging might have been in- volved. Seeds of Elaeocarpus luzonicus (Elaeo- carpaceae) as well as fruits and flowers of climb- ing pandans {Freycinetia sp.) were also found in the scat, suggesting a predator with omnivorous feeding habits. Currently, there is no known rec- ord of P. cumingi at this elevation and in the for- est type where the scat was found, but lowland secondary forest occurred no more than 1 km dis- tant. Most local hunters apparently pursue cloud rats only as a sideline to hunting other larger species; i.e., they will catch the rats when they encounter them but do not specifically go out to hunt them. The hunter who captured most of the 1988 spec- imens reported that he had taken about 50 of them in the previous year and considered them to be quite common, as did other local inhabitants. All 42 FIELDIANA: ZOOLOGY informants stated that they encountered them only in lowland forest, from about 150 m (the lowest elevation of patches of degraded forest) to about 900 m (the upper limit of lowland dipterocarp for- est). Informants said that cloud rats occur even in very small patches of degraded forest that exist as discontinuous chains of habitat along the steep banks of rivers. Cloud rats are said to spend most of their time in the forest or scrub but also some time in agricultural fields. They reportedly require large hollow logs or trees for nest sites and do not persist without such sites. They are said to be ac- tive only at night and to always spend the day in hollow trees or logs. Local residents told us that cloud rats eat the young leaves of papaya and other trees (both do- mestic and wild), sometimes the leaves of sweet potato (locally called camote), and both the leaves and fruit of sayote (Sacchium edule, a ground- growing squash). In Del Rosario (Site 9), a local hunter told us that P. cumingi fed on the clustered flame-red flowers of rarang {Erythrina subum- brans), which start to bloom in the midst of abaca and coffee plantations during the dry season. In February 1990, one animal was shot on such a tree in bloom in a coffee plantation close to the farmers' houses. Our informants said that the giant rats usually have one young per litter but occasionally have two and rarely three in a litter. They said that fe- males give birth in late November and December and that they have seen females with dependent young in February and March, which is usually the beginning of the dry season. The young were described as being "quite large" at birth, about "the thickness of a man's wrist." The young stay with the females for "a long time," and it is com- mon to capture a female with a nearly fully grown subadult. An adult male and adult female are oc- casionally captured in the same hollow tree, and sometimes the females have young with them at the time. All of these comments are consistent with those from informants on Catanduanes (Hea- ney et al., 1991). Cranial measurements (Table 1 1 ) are slightly larger than those of rats from Catanduanes (Hea- ney et al., 1991) but are much smaller than those of the northern giant cloud rat, Phloeomys palli- dus (Taylor, 1934, p. 395). Specimens from Mount Isarog and Catanduanes all have the dark brown pelage typical of this species (Fig. 23). The standard karyotype of P. cumingi (2n = 44, FN = 66) is quite distinct from that of P. pallidus (2n = 40. FN = 60). providing strong evidence that the two taxa are separate species (Rickart & Mus- ser, 1993). Specimens Examined — Total 13. Site 1 (3 pnm, 8 usnm); Site 10 (2 fmnh). Rattus everetti (Gunther, 1879) The common Philippine forest rat (Fig. 24) is a large (253.2 ± 43.9 g) rodent that occurs throughout the Greater Luzon, Greater Mindanao, and Mindoro Faunal Regions, as well as Cami- guin and Panay (Heaney et al., 1998; Musser & Heaney, 1992). It was the most commonly trapped mammal at all sites but was significantly more abundant in lowland dipterocarp forest at 450 m and 900 m than in other habitats (Fig. 12; Table 1 of Rickart et al., 1991). Trap success in 1988 varied from 0.66% to 2.81% with coconut bait and from 0.29% to 1.0% with earthworms; trap success was significantly greater with coconut bait (X: = 12.534; P < 0.001). Stomach contents of six snap-trapped specimens included seeds, green plant matter, and insect fragments. Captive ani- mals readily accepted several types of fruit, acorns, peanuts, coconut bait, sweet potato, ant and beetle larvae, adult insects (cicada, cricket, cockroach, robber fly, longhorn beetle, weevil), and fresh flesh of Apomys, Crocidura, and a Sphenomorphus lizard. Earthworms and milli- pedes were marginally accepted; captives rejected some seeds and fruits, an orchid bulb, a caterpil- lar, large ants, rove beetles, a harvestman, tender young leaves, moss, a mushroom, and flesh of a conspecific. Rattus everetti is best described as a broad omnivore. These rats were almost exclusively nocturnal. During the relatively dry conditions of the 1988 field study, only 3 (2.4%) of a total of 125 animals were taken during daylight hours. During the much wetter conditions in 1993-1994, two indi- viduals (18%) were trapped between midday and 16:00. Animals were trapped in a variety of sit- uations, often on steep terrain or above the ground surface. Many were trapped beside fallen logs, but rarely did they seem to be in clearly visible run- ways. We believe they are scansorial, often for- aging above the ground surface. In a logged-over area at ca. 500 m elevation at Site 9 in November 1989, an adult male was shot at night while it was sitting ca. 3 m aboveground on top of a mass of fruits in a Ficus minahassae, feeding on ripe figs. An adult female was hand-caught about 4 m up HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG. PHILIPPINES 43 Table 1 1. Mean (± SD) and range of selected cranial and external measurements of adult murid rodents (Mu- ridae) from Mt. Isarog, southern Luzon, Philippines. Sample size smaller than N is indicated by the number enclosed in parentheses after the range. Measurements taken from sample sizes of 2 and 3 are given as averages and their ranges. All measurements except weight are in millimeters. Basioc- Inter- cipital orbital Zygomatic Mastoid Nasal Species Sex N length width breadth breadth length Phloeomys cumingi M 2 — — — — — F 2 78.9 15.8 43.6 25.6 28.4 77.6-80.2 15.1-16.5 43.4-43.8 25.5-25.7 28.0-28.7 R. everetti M 12 49.6 ± 2.26 7.3 ± 0.24 24.8 ± 1.05 19.3 ± 0.57 20.0 ± 1.13 44.9-52.2 7.1-7.6 22.9-26.5 18.2-19.8 17.8-20.9 F 15 48.8 ± 1.95 7.2 ± 0.43 24.8 ± 1.20 19.0 ± 0.82 19.7 ± 0.82 45.0-52.2 (13) 6.4-7.9 23.1-26.5 (11) 18.4-20.5 18.4-20.5 R. exulans M 1 30.7 5.0 — — 12.2 R. tanezumi M 4 41.0 ± 2.66 6.2 ± 0.31 21.0 16.6 ± 0.82 15.1 ± 0.66 38.8-44.8 5.7-6.4 20.3-21.7 (3) 15.6-17.5 14.7-16.1 F 2 42.3 6.2 23.0 17.2 15.7 39.8-44.8 6.0-6.5 21.9-24.0 16.9-17.5 15.3-16.1 Rhynchomys isarogensis M 7 41.4 ± 0.30 6.8 ± 0.16 16.8 ± 0.46 15.3 ± 0.46 17.2 ± 0.50 41.0-41.7 6.5-7.0 16.2-17.4 14.9-15.7 16.7-18.2 F 6 40.8 ±1.15 6.6 ± 0.26 16.7 ± 0.56 15.2 ± 0.43 17.0 ± 0.61 39.3-42.4 6.4-7.1 16.0-17.6 14.7-15.8 16.3-17.8 in a tree at 16:00 in mossy forest at Site 17 on 25 April 1992. Scats of viverrids collected in 1993-1994 at 1150 and 1450 m contained bones and fur of R. everetti (Table 12). This species and Apomys mus- culus, both predominantly nocturnal, are the only two species in old-growth forest at these eleva- tions known to be prey of viverrid carnivores on Mount Isarog; the predominantly diurnal species have not been found in the scats (Balete, 1995). The 1993-1994 mark-recapture study at Site 18 (Balete, 1995; Balete & Heaney, 1997) showed that this species has an estimated mean distance moved between captures of 73 m (range 0-244 m), with males traveling significantly farther than females. Rattus everetti moved significantly lon- ger distances than Apomys musculus, which had an MDM of 42 m. Home range size of five indi- viduals (two males and three females) was esti- mated to be 0.41 ha (range 0.08-0.99 ha). During the same period, the density of this species was 1.2 individuals/ha, the lowest among the small mammals in mossy forest except Chrotomys gon- zalesi (Table 10), but its biomass of 333.3 g/ha was the second highest of all, next to B. granti. There was little evidence of female reproduc- tive activity during our study. Nulliparous females (N = 28) weighed 95-245 g, averaging 166.5 g. No pregnancies were noted, and the majority of females had inactive reproductive tracts. A few females taken in early May, at the end of our 1988 study, had enlarged reproductive tracts and ap- peared to be entering reproductive condition. For 21 females with placental scars (246 g, range 190-340 g, N = 20), the number of placental scars (including several multiple sets) ranged from one to 13; we suspect typical litter size to be between three and six. On nearby Catanduanes Island, nulliparous females weighed 110-270 g, primigravid females weighed 245-285 g, and multiparous females with placental scars weighed 280-350 g; the latter appeared to retain several sets of scars, making it impossible to estimate lit- ter size (Heaney et al., 1991). On Leyte, three females had four to six placental scars (Rickart et al., 1993). In contrast to females, many males caught in March, April, and May were in reproductive con- dition. Fourteen adult males (299 ± 47.0 g, range 225-390 g) had scrotal testes ranging from 6X8 mm to 15 X 28 mm in size. Scrotal testes also were recorded in two young adults (185 and 200 g, testes: 3 X 17 mm and 7 X 15 mm) and four subadults (159 + 51.5 g, range 105-225 g, testes: 4X7 mm to 6 X 11 mm). Juveniles consisting of six males (133 ± 7.0 g) and three females (95- 125 g) also were taken in both March and April. At Site 18, a juvenile female weighing 68 g was captured in December 1993 (Balete, 1995). On Catanduanes, males with scrotal testes weighed 44 FIELDIANA: ZOOLOGY Table 1 1 . Extended. Anterior Maxillary Palatal nasal Rostral Rostral Orbital Mini. II ill (Mil breadth Diastema width depth length length tooth row at P4 length 8.2 18.6 33.8 24.9 18.2 16.5 22.5 9.0-9.5 18.6-18.7 33.3-34.2 24.8-25.0 17.4-18.9 16.1-16.9 22.3-22.7 5.8 ± 0.25 11.2 ± 0.49 19.8 ± 1.05 18.1 ± 0.62 9.2 ± 0.31 9.2 ± 0.37 14.4 ± 0.92 5.4-6.2 10.3-11.7 17.8-21.4 17.0-19.1 8.6-9.7 8.9-9.9 12.7-15.4 5.4 ± 0.48 10.7 ± 0.45 19.2 ± 1.01 17.7 ± 0.61 9.0 ± 0.41 9.3 ± 0.32 13.8 ± 0.80 4.7-6.1 10.0-11.7 17.8-21.3 16.8-18.6 8.2-10.1 8.9-9.8 12.3-15.0 3.3 6.9 11.5 11.5 5.3 6.0 8.5 4.3 ± 0.26 8.9 ± 0.59 15.2 ± 0.91 14.9 ± 0.83 7.4 ± 0.41 7.8 ± 0.24 1 1 .4 ± 0.55 4.0-4.6 8.2-9.6 14.4-16.5 14.3-16.1 6.8-7.8 7.5-8.0 11.0-12.2 4.5 9.2 16.3 15.5 8.0 8.3 11.7 3.9-5.1 8.7-9.7 15.5-17.1 15.0-16.0 7.7-8.3 7.8-8.8 11.4-12.0 3.3 ± 0.05 4.9 ± 0.32 20.6 ± 0.38 9.9 ± 0.24 2.2 ± 0.05 6.4 ± 0.25 13.9 ± 0.27 3.2-3.3 4.4-5.2 20.2-21.3 9.7-10.3 2.1-2.2 6.0-6.7 13.4-14.2 3.2 ± 0.05 4.7 ± 0.20 20.5 ± 0.51 9.8 ± 0.20 2.2 ± 0.10 6.3 ±0.18 13.8 ± 0.33 3.2-3.3 4.5-5.0 19.7-21.0 9.6-10.1 2.1-2.3 6.1-6.6 13.3-14.2 230-240 g, and three subadults with abdominal testes weighed 190-230 g (Heaney et al., 1991). Measurements are given in Table 1 1 . Variation in size is substantial between islands within the Philippines (Heaney & Rabor, 1982; Heaney et al., 1991; Rickart et al., 1993); detailed analysis of geographic variation should be fruitful. Speci- mens from Mount Isarog, Catanduanes, and the Mindanao Faunal Region have a karyotype of 2n = 42, FN = 64, which is quite similar to the kar- yotypes of many Asian species of Rattus (Rickart & Musser, 1993). Specimens Examined — Total 140. Site 1 (27 usnm); Site 2 (1 pnm, 35 usnm); Site 3 (25 usnm); Site 4 (15 usnm); Site 5 (10 usnm); Site 6 (13 usnm); Site 8 (1 uplb); Site 9 (1 uplb); Site 12 (1 uplb); Site 13(1 uplb); Site 17 (1 fmnh, 2 pnm); Site 18 (4 fmnh); Site 20 (1 fmnh); Site 22 (2 fmnh); Site 23 (2 fmnh); Site 24 (2 fmnh). Rattus exulans (Peale, 1848) The Polynesian rat is a widespread commensal species found throughout the Philippines in dis- turbed areas associated with human habitation (Heaney et al., 1991, 1998). Our only records for Mount Isarog consist of specimens collected at 725 and 800 m by Rabor in 1961; we trapped none, despite intensive sampling. The elevational range of this species on the mountain (Sites 21 and 22) paralleled that of R. tanezumi (see below). Although Rabor (1966) provided no description of the vegetation at these sites, these specimens probably were taken in disturbed habitats. Mea- surements are given in Table 1 1 . Specimens Examined — Total 2. Site 21 (1 fmnh); Site 22 (1 fmnh). Rattus tanezumi Temminck, 1844 The Oriental house rat (Fig. 24) is a widespread Asian species (formerly included in Rattus rattus; Musser & Carleton, 1993) that occurs throughout the Philippines, usually as a commensal in dis- turbed habitats close to human habitation (Heaney et al., 1998; Lepiten, 1997). However, on Philip- pine islands where the native rodent faunas are depauperate, this and other usually commensal species can be found in old-growth forest (Heaney et al., 1991; Heideman et al., 1987; Rickart et al., 1993). On Mount Isarog, Rabor's records from Curry, Pili Municipality (Sites 19-22), indicated that this species was generally restricted to disturbed forest habitats and agricultural areas close to human set- tlements below ca. 800 m elevation. We captured none in 1988, despite intensive sampling in the forest. However, in December 1989 we captured HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 45 Table 1 1 . Extended. Total Tail Species length length Hind foot Ear Weight (g) Phloemys cumingi 692 280 84 36 1985 671-712 274-287 82-85 34-37 1920-2050 708 293 79 35 1893 680-752 (3) 280-314 (3) 74-85 (3) 34-37 (3) 1850-1980 (3) R. everetti 432 ± 29.9 215 ± 15.2 45 ± 2.2 26 ± 1.5 256 ± 56.4 384-481 (28) 187-244 (28) 40-48 23-29 (28) 180-390(29) 425 ± 25.4 214 ± 18.7 44 ± 2.1 26 ± 1.5 239 ± 40.4 366-474 (35) 181-239 (35) 38-47 22-29 (35) 170-340 R. exulans — — — — — R. tanezumi — — — — — Rhynchomys isarogensis 294 ± 8.3 280-305 (15) 286 ± 8.6 270-298 (9) 121 ± 3.2 115-126 (16) 115 ± 3.6 108-118 (9) 39 ± 0.6 38-40 (16) 38 ± 1.0 37-40 (9) 22 ± 0.8 21-23 (16) 22 ± 0.5 21-23 (9) 125 ±11.4 110-145 (16) 127 ± 14.0 110-156 (9) six R. tanezumi within the compound of the PLDT telecommunications relay station at 1450 m ele- vation on the southern slope of Mount Isarog (Site 16). Our sample consisted of an adult female with small mammae (228 g) and five juveniles of un- known sex (31.3 ± 4.06 g). The presence of the species at this facility, constructed in the 1960s within the upper montane forest zone, is clearly a legacy of past disturbance and the continued pres- ence of humans in the area. Whereas these rats were common around the PLDT building, they were not taken in surrounding forest, where we caught Archboldomys luzonensis, Batomys granti, Chrotomys gonzalesi, Rattus everetti, and Rhyn- chomys isarogensis. This finding suggests that the species is restricted to heavily disturbed areas and is unable to colonize old-growth forest on the mountain. The name Rattus tanezumi is used for the 2n = 42 group of Asian commensal rats that are distin- guishable from the R. rattus group with 2n = 38/ 40 (Musser & Carleton, 1993; Rickart & Musser, 1993) Specimens Examined — Total 13. Site 8 (1 uplb); Site 15 (6 uplb); Site 19 (1 fmnh); Site 21 (1 fmnh); Site 22 (3 fmnh). Rhynchomys isarogensis Musser and Freeman, 1981 The Isarog shrew-rat (Fig. 25) was described in 1981 on the basis of a single specimen collected by Rabor in 1961 (Musser & Freeman, 1981). In 1988, we found this medium-sized murid (122.5 ± 9.5 g) to be common in montane and mossy forest from 1 125 to 1750 m and to be absent from lowland forest; it was significantly more common in mossy forest than in other habitats (Table 1 of Rickart et al., 1991). Trap success ranged from 0.73% to 4.41% with earthworm bait and 0.07% to 0.19% with coconut bait. Overall trap success was greater with earthworms than with coconut bait (x2 = 58.812, P < 0.001). In 1993-1994, the mean density of this species was estimated to be 2.6 individuals/ha, twice that of R. everetti, and its biomass of 328.4/ha was only slightly lower than that of R. everetti (Table 10). We recorded movements of a single male, which was captured thrice in the span of 3 days, having moved an average of 50 m (range 40-60 m). Too few re- captures were made to estimate home range size (Balete & Heaney, 1997). The stomachs of six snap-trapped specimens contained earthworms, amphipods, insect larvae, (Coleoptera, Diptera), and adult insects (Diptera, Orthoptera). None contained recognizable plant material. Two captives avidly accepted earth- worms and readily accepted beetle grubs and pu- pae, amphipods, isopods, small millipedes, and adult crickets. Hard-bodied insects, small snails, meat of various rodents, and all plant material were unequivocally rejected. Captives were especially adept at handling 46 FIELDIANA: ZOOLOGY Table 12. Composition of viverrid scats collected at various elevations on Mt. Isarog from December 1993 to April 1994. Plant samples in the scats consisted mainly of fruits (Elaeocarpus luzonicus) or flowers and leaves (Freycinetia sp.). Invertebrates were represented by ovipositors and exoskeleton (orthopterans) or elytra and legs (coleopterans). Remains of Phloeomys cumingi and a frog consisted entirely of bones, while those of Apomys musculus and Rattus everetti were comprised of bones and fur. Elevation Date N (m) Plants Invertebrates Vertebrates 12 Dec 1993 1 1150 E. luzonicus Unidentified R. everetti 16 Dec 1993 1 1550 Freycinetia Orthoptera A. musculus 20 Dec 1993 1 1550 Freycinetia 3 Feb 1993 2 1150 E. luzonicus Coleoptera P. cumingi small frog 17 Feb 1994 2 1600 Freycinetia Orthoptera A musculus 12 Apr 1994 1 1450 R. everetti earthworms. Small earthworms (<1 g) were quickly ingested whole (end-on) with minimal processing. Larger worms were held with the forepaws and eaten progressively from one end. The thin, sharp incisors were used to tear off por- tions of the prey, which were swallowed whole. Periodically the mouth grip was transferred to a point 2-3 cm from the damaged end, and the worm's gut contents were extracted through this opening by vigorous squeezing and pushing movements with the forefeet. One captive con- sumed a 6-g worm in approximately 1 min. Our data indicate that R. isarogensis is a specialized vermivore but that other soft-bodied invertebrates are also included in the diet. This species was predominantly nocturnal; out of a total of 32 animals captured in 1988, only 3 (9.4%) were taken during daylight hours. Animals were trapped exclusively on the ground in a va- riety of situations, most often in areas of moderate to dense cover. Most specimens were trapped on broad (5-8 cm) trails that were kept free of dead Fig. 24. Adult Rattus everetti (below) and R. tanezumi (above), showing the relative size and proportions of these species. February 1988, Catanduanes Island, L. R. Heaney. HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 47 Fig. 25. Adult Rhynchomys isarogensis. 22 March 1988, Site 3, L. R. Heaney. leaves and other obstructions; these trails could often be seen running for dozens of meters, merg- ing with other trails. The basic morphology (grac- ile body form, long and muscular hind limbs, long but narrow hind feet, slender forefeet with small claws) and our observations of captives indicate that this species is a highly active saltatorial rat. We noted that the dorsal skin from shoulders to rump contained a tough, moderately thick matrix of connective fibers, quite unlike that of any other mammal in the Philippines; it is reminiscent of the dermal shields of elephant shrews (Rathbun, 1978). Two pregnant females (115 and 125 g) taken in late April each had a single embryo (CRL = 6 and 10 mm). Five postpartum females (125 ± 1 1.2 g) taken in both March and April had one to three placental scars (including some with differ- ences in degree of pigmentation that we interpret as being from several pregnancies). An adult fe- male (128 g) collected in February 1994 had a single embryo (CRL = 1 mm). Ten adult males (126 ± 9.8 g) in breeding condition had scrotal testes ranging in size from 8 X 14 mm to 12 X 20 mm and convoluted epididymides. Three ju- venile males (49.5-59 g) were also caught during March and April. The karyotype is 2n = 44, FN = 52/53, and there are karyological similarities to Chrotomys and Apomys (Rickart & Musser, 1993). Measure- ments are provided in Table 1 1 . Specimens Examined — Total 38. Site 3(1 usnm); Site 4 (6 usnm); Site 5 (3 usnm); Site 6 (22 usnm); Site 17 (2 fmnh, 2 pnm); Site 18 (1 fmnh). Order Carnivora Family Viverridae — Civets Paradoxurus hermaphroditus (Pallas, 1777) The common palm civet is found throughout the Philippines and much of Southeast Asia, where it is common in both agricultural areas and forests. A male with scrotal testes measuring 17 X 13 mm was trapped in March 1988 at 1550 m elevation (Site 5). On the evening of 29 De- cember 1989, a young adult male was shot by a 48 FIELDIANA: ZOOLOGY 1966 (peak) 1500" 3 1000- W 500- < • • - • • • • [i i I • 7 T , , 1 I • . 1 • 1 1 ; 9 i'S S-S SI *2 ? -2 3 *ij J5? *3 5 c-s Fig. 26. Elevational distribution of large mammals on Mount Isarog. local farmer as it was apparently feeding on ripe fruit high in a coffee tree growing in an agricul- tural area at 350 m elevation (Site 8). Another young male was shot at night by a hunter after being treed by dogs in disturbed forest at 700 m elevation (Site 12). A second male specimen from this site was caught in a native snare. Ra- bor's team took a specimen at 725 m, probably in disturbed lowland forest, in 1961. These re- cords indicate that the species occurs over most or all of the elevational gradient (Fig. 26). We suspect that it is the more common of the two local viverrids. The majority of scats collected in 1993-1994 at various sites between the lowland montane and mossy forest (Table 12) contained a combination of plant materials (mostly fruits of Elaeocarpus luzonicus and Freycinetia sp.) and remains of sev- eral rodents (bones and fur), including Apomys musculus, Phloeomys cumingi, and Rattus eve- retti. The omnivorous feeding habits of the pred- ators that deposited these scats lead us to suspect that these were from P. hermaphroditus. This is consistent with the known feeding habits of this species (Alcala & Brown, 1967; Auffenberg, 1988; Bartels, 1964; Rabor, 1955, 1977). Specimens Examined — Total 6. Site 5 ( 1 usnm); Site 8 (2 uplb); Site 12 (2 uplb); Site 18(1 fmnh); unknown site (1 amnh). Viverra tangalunga Gray 1832 The Malay civet is found throughout much of Southeast Asia, including the Philippines, but is common only in forested habitats. We obtained two specimens from local hunters. The one from barangay Del Rosario was snared on 6 December 1989 in disturbed lowland forest at 700 m eleva- tion (Site 12). The other was purchased on 24 March 1988 from a hunter who had snared it on the northeastern flank of the mountain at about 450 m in a patch of second-growth forest in an area that is dominated by agriculture. Rabor's crew took two specimens, one recorded as "3000-3500 ft" (Site 22) and another recorded as "5500 ft" (Site 23). Together, these records imply that Malay civets range from the bottom to the top of the mountain (Fig. 26). Stomach contents of the specimen from bar- angay Del Rosario consisted mostly of slugs and land snails. Auffenberg (1988) suggested that V. tangalunga in Caramoan is largely carnivorous, feeding on rodents and freshwater crabs. An adult female from Leyte had stomach contents that in- cluded two large centipedes, one large snail, and at least one skink and one small snake (Rickart et al., 1993). Scats of viverrids collected in 1993- 1994 (Table 12) contained mostly plant materials and remains of the rodents Apomys musculus, Phloeomys cumingi, and Rattus everetti, indicat- ing they were eaten by an omnivorous predator, most likely palm civets (see account for P. her- maphroditus). Specimens Examined — Total 1. Site 12 (1 uplb); northeast flank of Mount Isarog (1 usnm); Site 22 (1 amnh); Site 23 (1 amnh). Order Artiodactyla Family Suidae — Pigs Sus philippensis Nehring, 1 886 The Philippine wild pig occurs within the Lu- zon, Mindanao, and Mindoro Faunal Regions, and was considered by Groves (1997) and Grubb (1993) to be specifically distinct from the other native pig species, Sus barbatus (occurring in the Palawan Faunal Region. Borneo, and the Malay Peninsula) and S. cebifrons (restricted to the Ne- gros-Panay Faunal Region). On Mount Isarog, local hunters told us that HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 49 wild pigs were still present in the remaining old- growth and disturbed forest (Fig. 26), although they had become uncommon. In 1988, local peo- ple told us that it had been over a year since one had been caught; we saw several pit traps and one snare, and we were told that several settlers on the mountain were still engaged in pig hunting with the aid of hunting dogs. During 1989-1990, pig wallows and signs of foraging were common- ly seen in disturbed forest at ca. 600-800 m ele- vation (Sites 12 and 13). On several occasions at Site 18, fresh tracks of wild pigs were encoun- tered along creeks in the mossy forest. On 27 Jan- uary 1990, a juvenile male was captured by a lo- cal hunter while it foraged near a dry creek at 700 m elevation (Site 12). The animal was less than 1 year old and probably recently weaned; most of the milk teeth were still present, but some of the permanent teeth were starting to erupt. This was said to be the first wild pig taken from the area in more than a year. Head plus body length = 620 mm; tail length = 60 mm. Specimens Examined — Total 1. Site 12 (1 pnm). Family Cervidae — Deer Cervus mariannus Desmarest, 1822 This species is native to the Luzon, Mindanao, and Mindoro Faunal Regions of the Philippines and has been introduced to the Mariana, Caroline, and Bonin Islands (Grubb, 1993). This species and C. alfredi (restricted to the Negros-Panay Faunal Region) were formerly included within C. unicolor but were recognized as distinct species by Grubb and Groves (1983). We received no recent reports of deer in low- elevation forest on Mount Isarog, and residents believed they had been gone from the lowlands for many years. However, at least some deer per- sist at higher elevations on the mountain. On sev- eral occasions in 1988 and 1990, we came upon fresh deer droppings and tracks in mossy forest between 1750 and 1850 m (Sites 6, 17, and 18; Fig. 26). Our guide in 1989-1990 said that nipped fiddleheads of low-lying tree ferns in the mossy forest had been browsed upon by deer. Analysis and Discussion Adequacy of Sampling Surveys of the mammals of any region, es- pecially in poorly known parts of the tropics, are rarely carried out with sufficient intensity or over sufficient periods of time that they can be consid- ered complete or precise (Voss & Emmons, 1996). Accordingly, we must attempt to evaluate the de- gree of completeness of our data so that we may then make meaningful and appropriate compari- sons to other sites. Our survey procedure consist- ed of (1) sampling extensively along elevational transects in all major types of habitat; (2) em- ploying standardized sampling procedures; (3) plotting species-effort curves, which provide an index of the likelihood of captures of further spe- cies; and (4) estimating the relative abundance of individual species, to determine the habitat where they are most abundant (Heaney et al., 1989, 1991; Rickart et al., 1991, 1993). Whenever pos- sible, we then supplemented the initial data with detailed studies, as Balete (1995) has done in this case. We believe there are five principal habitats that need to be sampled to assess the mammal fauna on any given Philippine island: lowland forest, montane forest, mossy forest, second growth (at all elevations), and caves (Heaney et al., 1989, 1991; Rickart et al., 1993). In our surveys of Mount Isarog, we believe that the first three hab- itat types were adequately sampled. Very few nat- ural caves occur on Mount Isarog itself, but there are caves in low-lying areas within 10 km of the mountain; our limited sampling of caves is a weakness of this study. The weakest portion of our survey is that of second-growth habitat, where we did only limited and incidental sampling. The accuracy and thoroughness of sampling also vary with taxonomic group and specific sampling tech- niques, so various groups need to be assessed dif- ferently. In the present study these include (1) large megachiropteran bats (Pteropus and Acero- don), (2) small megachiropterans (all other gen- era), (3) microchiropteran bats, (4) small rodents and insectivores, and (5) large, nonvolant species. Our knowledge of the large megachiropterans of Mount Isarog is incomplete, largely because flying foxes typically fly well above the canopy and approach feeding trees from above, rarely de- scending low enough to encounter mist nets. At present, only two species are known with certain- ty (Pteropus hypomelanus and P. vampyrus, each 50 FIELDIANA: ZOOLOGY ~3 B 3 u 50 100 150 200 250 300 350 Cumulative Net-nights Fig. 27. Cumulative species-effort curve for the number of fruit bat species captured in nearly 350 net- nights in all habitats on Mount Isarog in 1988. based on a single record), although we found in- direct evidence for the occurrence of a third spe- cies (P. leucopterus). There is a strong possibility that two additional widespread species (Heaney et al., 1998) may occur on the mountain (Acerodon jubatus and Pteropus pumilus). Recent studies of small megachiropterans in the Philippines indicate that our 1988 samples of 54- 75 net-nights at Sites 1-5 (475-1550 m; Table 4) are likely to have yielded approximate species richness and proportional abundance, although rare species may have been missed (Heaney et al., 1989; Heideman & Heaney, 1989). On a replicate transect of more limited scope on the south side of the mountain in 1989-1990 (Sites 7-17) two additional species were found at very low eleva- tions in agricultural habitat, thus extending the documented elevational range for several species (Fig. 13). A species-effort curve (Fig. 27) for the 1988 season shows a jump in species richness at the end of the season, when our persistent efforts yielded specimens of Harpyionycteris whiteheadi. At least one species that is now rare throughout the Philippines could occur in the area (Eonycteris robusta; Heaney et al., 1998), but capture of ad- ditional species at middle to high elevation on the mountain is unlikely because all other species known to occur in this part of the Philippines were netted. We conclude that our samples are likely to accurately reflect the number of species, relative abundance, and patterns of habitat use of small fruit bats on Mount Isarog, with the exception of one rare species (i.e., Eonycteris robusta). Microchiropteran bats, which differ from mega- chiropterans in possessing the ability to echolo- cate, are difficult to capture in mist nets, and mist net studies typically result in underestimation of their diversity and abundance (Francis, 1989). Our sampling of microchiropterans in forests relied solely on mist nets, so we consider our data to be useful as indicators of general patterns but not suitable for detailed interpretation or comparison. More sampling using different techniques (es- pecially harp traps) in forest, caves, and second- growth habitat would very likely increase the number of microchiropteran species. Our trapping surveys of small rodents and in- sectivores were extensive. Previous studies have shown that in the Philippines, samples based on 900 or more trap-nights are effective in assessing species richness and approximately proportional abundance, although rare species may still be missed (Heaney et al., 1989; Rickart et al., 1991). Our studies on Mount Isarog in 1988 (described in detail by Rickart et al., 1991) included more than 1,100 trap-nights in all native habitat types and included two types of bait (fried coconut and live earthworms) at all sites. Species-effort curves (see Rickart et al., 1991) indicate that it is quite unlikely that additional species of small mammals remain to be trapped on the mountain as a whole, although some individual sites might yield small increases in species richness with the addition of some locally rare species (e.g., Site 5 at 1550 m). A less intensive replicate transect on the south side of the mountain in 1989-1990 did not yield any additional species or extensions in docu- mented elevational range. On the basis of these data, we conclude that our sampling of the small mammal fauna probably yielded an accurate as- sessment of the number of species present on the mountain and probably showed their relative abundance and elevational range fairly precisely; i.e., some small changes in elevational range, rel- ative abundance, and habitat associations may be documented by future studies, but we expect no major changes. At present, there are six species of medium- or large-sized mammals known from Mount Isarog. These include one primate, one rodent, two car- nivores, and two ungulates. We have no reason to suspect that there are any other large species on the mountain because their presence is generally easy to document (either directly or through local informants). We know that all but one species (Phloeomys cumingi) once utilized the entire ele- vational gradient and that all were once moder- HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 51 *8 "3 [X, 6 en .2 4 o 01 Oh CO - □ Mossy Forest ■ Trans. Montane/ Mossy Forest o O., ,. A. A Montane Forest **-.% ,.-•*' *'». A Trans. Lowland/ Montane Forest 0 ♦'"'A "•» O Lowland Forest .*•*" •, '%-x • Disturbed Lowland Forest - #'' Leyte .- \ \ \ ■ ,•* V^ \ \ -r' Negros "V^ ■ □ vxLuzon b - "--a «-----n • 1000 Elevation (m) 1500 Fig. 28. Number of species of small fruit bats recorded along the elevational gradients on Mount Isarog (this study; Fig. 13), Mount Pangasugan, Leyte, and Mount Guinsayawan, Negros (Heaney et al., 1989). ately common. However, we know few details about their use of the various habitats. In summary, we believe our data on small non- volant mammals to be strongest (with only minor "hanges in elevational range and abundance likely ith more intensive study), that on small fruit bats > be sufficient for documenting patterns of spe- cies richness and abundance (but with documen- tation of rare species and some minor changes in elevational range possible), that on large mam- mals to indicate the species that are present (but little about patterns of abundance), that on insec- tivorous bats to indicate rough patterns of species richness (but with future studies likely to add sub- stantially to the number of species), and that on large bats to be quite incomplete in all respects. On this basis, we now proceed to interpret the data in appropriate ways. Patterns of Species Richness and Relative Abundance of Small Fruit Bats Small fruit bats were most diverse at our lowest sampling sites on Mount Isarog, but species rich- ness declined steadily with increasing elevation (Figs. 13 and 28; Fig. 28 is modified from Heaney & Rickart, 1990, on the basis of the 1989-1995 data in Fig. 13). The degree of similarity to the pattern on Leyte and Negros, the only two sites from which comparable data currently are avail- able (Heaney et al., 1989; Heaney & Rickart, 1990), depends on the basis of comparison. On Mount Pangasugan, Leyte, the high species rich- ness seen in the lowlands drops off quickly with increasing elevation, but the elevational gradient is truncated (the mountain peak stands at only 1150 m). On Mount Isarog and Mount Guinsay- awan, Negros, which are similar in peak elevation at 1966 and 1788 m, respectively, the elevational decline in the number of species is much more gradual. However, when one compares the decline with respect to habitat type, the patterns become more similar (Fig. 28). On all three mountains, disturbed lowland forest has six or seven species and mossy forest has two or three species, with gradually declining numbers between. We con- clude that the patterns follow vegetation and cli- matic changes that are associated with elevation and that elevation per se is less strongly correlated with species richness. Netting success, which is our measure of abun- dance, also shows generally similar patterns on all three mountains (Fig. 29). We lack data on Mount Isarog from lowland agricultural areas that pro- vided the highest densities of fruit bats on Leyte and Negros, but otherwise the pattern of decline is similar on all three mountains. The most con- spicuous difference among them is the two- to threefold higher density on Negros than on the other islands; we have no ready explanation for this difference. An agricultural site on Catandu- anes Island, which is quite close to Mount Isarog (Fig. 1; Heaney et al., 1991), had bat density and species richness comparable to that in mixed ag- 52 FIELDIANA: ZOOLOGY 11 - 1 10 - \ \ n Mossy Forest \ ■ Trans. Montane/ Mossy Forest — x A Montane Forest -C 9- \ \ A Trans. Lowland/ Montane Forest bO \ O Lowland Forest *C \ • Disturbed Lowland Forest ■ — 8- \ 0) \ 2 \ \ CD 7- * Negros \ 15 X CO 6 - • \ — \ \ 5 5 - \ \ b V \ en .An t/3 4- *' N N • Leyte \ \ 3 3i N \ \ N ■4-> \ 0> ^ 2 2 - \ \ \ Luzon \ 1 - \ ...o *- h o— ""-■a o- 0 500 1000 1500 2000 Elevation (m) Fig. 29. Relative abundance of small fruit bats recorded along the elevational gradients on Mount Isarog (this study; Table 4), Mount Pangasugan, Leyte, and Mount Guinsayawan, Negros (Heaney et al., 1989). ricultural land and secondary forest on Mount Is- arog, but a single lowland forest site on Catan- duanes had density and species richness lower than on Mount Isarog. When these data are again compared on the basis of habitat type rather than elevation, the consistency of the pattern increases. We conclude that the pattern of declining abun- dance of small fruit bats with elevation is consis- tent and probably primarily associated with changes in habitat rather than elevation per se, as was also the case for species richness. Patterns of Species Richness and Relative Abundance of Nonvolant Small Mammals Along our 1988 transect on the western side of Mount Isarog (Sites 1-6), the number of nonvo- lant small mammals was lowest in lowland forest (three species) and highest in montane and mossy forest (eight and seven species, respectively; Fig. 12, and Table 1 of Rickart et al., 1991). The num- ber of species captured showed a general increase from lowland forest to montane and mossy forest, although different rank correlation measures yield different results: species richness was not signifi- cantly correlated with elevation (r, = 0.80, P > 0.05), but a strong positive trend was indicated by a significant association between ranked elevation and ranked species richness (P < 0.05, Olmstead Tukey test; Rickart et al., 1991). These results support an earlier prediction of increasing species richness with elevation by Heaney et al. (1989) and are in clear contrast with widespread patterns seen for bats and birds, among which maximum species richness is in lowland forest (Diamond, 1972; Graham, 1990; Heaney et al., 1989; Ter- borgh, 1977). The relative abundance of nonvolant mammals, as measured by trap success, also varied with el- evation (Fig. 30). The values represented for Mount Isarog are from the 1 988 field season using the standardized sampling described in detail by Rickart et al. (1991), based on overall unweighted trap success (Table 2 in Rickart et al., 1991). The number of individuals captured showed a general increase from lowland forest to montane and mossy forest; although abundance was not signif- icantly correlated with elevation (r, = 0.80, P > 0.05), deletion of the anomalous 1550-m site re- sulted in a significant correlation for unweighted overall success with the remaining sites (Rickart et al., 1991), which suggests a general increase in relative abundance with elevation, as predicted HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 53 §10 E " E S 6 on e< 2 Ml. Guinsayawan, Negros 4 ^ / Mt. Isarog. Luzon Q Mt. Pangasugan, Leyte ^^ ^0" ~" ~ O* # 0 200 400 600 800 1000 1200 1400 1600 1800 Elevation (m) Fig. 30. Relative abundance of small mammals (in- sectivores and murid rodents) recorded along the ele- vational gradients on Mount Isarog (this study; Rickart et al., 1991), Mount Pangasugan, Leyte, and Mount Guinsayawan, Negros (Heaney et al., 1989). from earlier studies on Leyte and Negros (Heaney et al., 1989). The exceptionally high relative abundance values from Negros are of interest be- cause this community is composed of only two native species plus three non-native species, and the non-native species are much more abundant than the native species. Further studies of species richness and relative density on other mountains in the Philippines are needed to determine general patterns. The densities (measured as number per hectare, rather than as number per 100 trap- nights) recorded at Site 18 are among the highest known for small mammals in the tropics (Balete & Heaney, 1997). Patterns of Species Richness of Microchiropteran Bats No detailed estimates of Philippine microchi- ropteran faunal richness are available, and few comparisons are possible. With 14 species docu- mented on the mountain and two others recorded nearby, Mount Isarog compares favorably with the 15 species recorded from Catanduanes (Hea- ney et al., 1991), 17 recorded from Leyte (Rickart et al., 1993), and 14 recorded within a single sam- pling area at 200-500 m on Mount Makiling, La- guna Province (Ingle, 1992). We captured 82 microchiropterans on the mountain in 1988 at Sites 1-6; they represented 12 species (Table 7). Despite a similar netting ef- fort at all but the highest elevation, we found a steady decline in species richness along the tran- sect from seven to one species (Fig. 16), in a man- ner similar to that seen in small fruit bats (Figs. 13 and 28). No clear pattern was evident on Ley- te, the only site with comparable transect data (Rickart et al., 1993). As noted above, these data should be taken only as rough indications of pat- terns, because our sampling of insectivorous bats was almost certainly incomplete. There are few caves, rock shelters, or tunnels on or near Mount Isarog, and we captured only two species of insectivorous bats in such places {Emballonura alecto and Miniopterus schreiber- si). The records of Hipposideros bicolor and H. pygmaeus from Pasacao may have originated from a cave, because these bats often roost in such places (Heaney et al., 1998). Biogeography Mount Isarog and the adjacent island of Catan- duanes (Heaney et al., 1991) currently are the only sites in southern Greater Luzon where the mammalian faunas have been well studied (Hea- ney, 1986); only scattered records exist from the rest of the Bicol Peninsula and associated islands. Our comments on biogeography therefore must necessarily be based on very limited information. The 44 native species of mammals known to occur on or near Mount Isarog constitute a large fraction of the 83 native species known from Lu- zon (Heaney et al., 1998). Current evidence sug- gests that the Bicol Peninsula constitutes a dis- tinctive subregion of the Greater Luzon region. Archboldomys luzonensis, Chrotomys gonzalesi, and Rhynchomys isarogensis are currently known only from Mount Isarog. Phloeomys cumingi is known only from the Bicol Peninsula, the islands of Catanduanes and Marinduque, both of which were part of Greater Luzon during Pleistocene pe- riods of low sea level, and the adjacent portions of central Luzon (Heaney, 1986; Oliver et al., 1993a). All four of these species have their sister taxa in central and northern Luzon (Rickart et al., 1991). As the highest forested peak in southern Luzon, Mount Isarog is likely to support the richest mammalian fauna in the region; current evidence is consistent in showing that the maxi- mum diversity of nonvolant mammals in the Phil- ippines (which are especially rich in endemic spe- cies) is associated with areas of high topographic 54 FIELDIANA: ZOOLOGY diversity that retain old-growth forest cover (Hea- ney et al., 1989; Rickart et al., 1991; Heaney, un- publ. data). However, this hypothesis is in need of careful testing, which can be accomplished only by intensive survey of other mountains on the Bicol Peninsula. Four mountain peaks on the Bicol Peninsula hold potential for testing the impact of topograph- ic diversity on mammalian diversity: Mount Iriga, Mount Malinao, Mount Mayon, and Mount Bu- lusan (Fig. 1). In a recent brief survey of Mount Bulusan at the southernmost tip of Luzon, D. S. Balete found only scattered remnant forest on the mountain, with volcanic eruptions, extensive log- ging, agricultural clearing, and storm damage hav- ing contributed to the destruction of the natural vegetation. A limited amount of trapping yielded only Rattus everetti and R. tanezumi, and netting yielded only common fruit bats, which are highly tolerant of disturbance (specimens in fmnh and pnm). It is unlikely that any habitat remains on Mount Bulusan that could support the endemic mammals of the Bicol Peninsula, with the excep- tion of Phloeomys cumingi, which is relatively tolerant of disturbance (see species account). Mount Mayon, the tallest mountain on the Bi- col Peninsula at 2421 m, is an active volcano that erupts frequently. The upper portion of the moun- tain is covered by exposed volcanic ash flows, welded ash, and lahars; the lower portions are covered by a mixture of ash flows, disturbed for- est, and agricultural fields. It seems an unlikely place to support populations of the endemic mam- mals. Mount Iriga, which reaches 1337 m, is now al- most completely denuded of natural vegetation up to the peak, and we doubt that it supports any endemic species at present. Mount Malinao, which reaches 1548 m, is a dormant volcano midway between Mount Mayon and Mount Iriga (Fig. 1). The lowland forest is extensively fragmented, with virtually all lowland areas heavily cultivated and populated by humans, but portions of the montane and mossy forest re- main intact. Of the four poorly studied high peaks on the Bicol Peninsula, this is the one most likely to support populations of the species currently known only from Mount Isarog. To the best of our knowledge, no surveys of the mammals of Mount Malinao have been conducted. Another interesting and important point of comparison is Mount Banahaw, the highest peak (2165 m) between Mount Isarog and the two mountain ranges of northern Luzon, the Central Cordillera and the Sierra Madre (Fig. 1). This mountain might represent either the northernmost point of the Bicol fauna, the southernmost point of the northern mountain fauna, a mixture of the two, or, depending on its degree of isolation, an- other local center of endemism. In an unpublished M.Sc. thesis, Rosell (1996) reported the presence of an unidentified Rhynchomys, as well as four species of Apomys, reinforcing the importance of study and publication on this exciting site. Distribution and Ecology of Non-native Species: Are They a Threat to Native Murids? A subject of increasing interest to conservation biologists and managers is the impact of non-na- tive (= exotic) species on the native organisms in protected areas. On oceanic islands, introduced species often have been able to invade old-growth habitats and displace the native species (e.g., At- kinson, 1989; Case, 1996; Ebenhard, 1988). Goodman (1995) recently suggested that Rattus rattus, a non-native species on Madagascar, is dis- placing endemic murids in forests on Madagascar and suggested that other communities of endemic murids might be similarly affected in many pro- tected areas in the tropics, especially on islands. Our data from Mount Isarog, although not de- signed specifically to investigate this issue, are highly relevant. We sampled extensively in both disturbed and old-growth lowland forest adjacent to agricultural land where commensal rats are abundant, including Rattus tanezumi, which is closely related to Rattus rattus. The results showed that the non-native murids that occur in the vicinity are entirely absent from forest on Mount Isarog; we captured only a few of the non- native species, and those only in or immediately adjacent to occupied buildings. In second-growth lowland forest that was regenerating under a scat- tered canopy of a non-native legume (Leucena leucocephala), we captured the native Crocidura grayi, Apomys microdon, and Rattus everetti and no Suncus murinus, Mus musculus, Rattus exu- lans, or Rattus tanezumi, which are common in and around human dwellings and in agricultural areas. This was the case even where a radio relay station (where non-native rats were present during our study) had been in place for more than three decades. We conclude that on Mount Isarog, com- mensal species of mammals are unable to displace the native species in either old-growth natural HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 55 habitat (i.e., old-growth lowland forest) or dis- turbed but regenerating natural habitat adjacent to agricultural areas where non-native species are common. We found similar results on Leyte Is- land, where Rattus tanezumi was limited to heavi- ly disturbed second growth adjacent to agricultur- al fields and was absent from all areas of old- growth forest (Heaney et al., 1989; Rickart et al., 1991). However, we found quite different conditions on Negros Island (Heaney et al., 1989; Heideman et al., 1987). Negros has a depauperate native small-mammal community, consisting solely of a shrew (Crocidura ne grind) and a forest mouse (Apomys sp.). In all forest habitats at all elevations on Negros, whether disturbed or old growth, we found that the commensal species Suncus muri- nus, Rattus exulans, and Rattus tanezumi domi- nated, with the native species present in smaller numbers. Similarly, we found Suncus murinus and Rattus exulans (but not Rattus tanezumi) to be common in forest on Camiguin Island, where there are only five native species of small mam- mals (Heaney & Tabaranza, 1995). These observations led us to propose the hy- pothesis that the number of species in the native community of small mammals determines the suc- cess of non-native small mammals in invading na- tive habitat on oceanic islands. Where few native species are present (e.g., Camiguin and Negros), the non-native species flood into the forest; where many native species are present, few or no non- native species are able to invade undisturbed hab- itats. This hypothesis could easily be tested on other islands in the Philippines, where there is great variation in the richness of the small-mam- mal fauna (Heaney, 1986). It could also be tested in forest fragments on the larger islands; for ex- ample, we predict that a patch of restored natural forest isolated from undisturbed native vegetation and thus with no source of colonizing native spe- cies could easily be invaded by non-native spe- cies, whereas a regenerating natural forest at the edge of native forest (which has a source of native small mammals) would be highly resistant to in- vasion by non-native species. Testing this hypoth- esis could produce information of great value to conservation and biodiversity managers. Conservation and Management of the Mount Isarog Mammalian Fauna The 48 species of mammals currently known from or near Mount Isarog include species that vary greatly in their breadth of distribution, range of abundance, and conservation status. Four spe- cies (Suncus murinus, Mus musculus, Rattus ex- ulans, and Rattus tanezumi) are not native and will not be discussed further in this section. The others fall into six broad categories. The first category is composed of three species that we believe once occurred on Mount Isarog but appear to no longer be present: Hipposideros bicolor, H. pygmaeus, and Bullimus luzonicus. As noted in the species accounts, there are no verified records of these species on the mountain, but all have been found nearby. Although there are no nearby records, we suspect that Eonycteris robus- ta, a widespread endemic fruit bat (Heaney et al., 1998), also once occurred on Mount Isarog. The three bats are all associated with caves in lowland forest (Heaney et al., 1998). Aside from the small tunnels at several sites that are near small patches of second-growth forest, there may be no caves left anywhere near Mount Isarog that have not been heavily disturbed by guano miners and bat hunters, and probably few to none that have forest nearby because of virtually complete clearing of the lowlands. Bullimus luzonicus is proving to be rather enigmatic; although it was recorded fre- quently up through about 1965, we know of few recent records, and those seem to be associated with bamboo. We regard these species as being of special concern, especially in southern Luzon, but also throughout the country; additional surveys are needed to determine their status and habitat needs and to develop recommendations for pro- tection programs that will ensure their continued existence. The second category consists of three species of bats that we detected in our samples but were uncommon: Eonycteris spelaea, Rouse ttus am- plexicaudatus, and Miniopterus schreibersi. All are usually common in the Philippines, but we found only a few. All of these bats require caves as roosting sites; their relative rarity suggests that caves in the area of Mount Isarog have been se- verely disturbed by human activity and can no longer support large populations of these bats. We regard these data as reinforcing the conclusion that protection for caves should be made a high priority in southern Luzon. The third category consists of seven species that are less common than formerly because of the combination of habitat destruction and overhunt- ing. These species include the large fruit bats (Pteropus hypomelanus, P. leucopterus, and P. vampyrus) that once were common in forested 56 FIELDIANA: ZOOLOGY habitats but are now quite uncommon in most places in the Philippines (Heaney et al., 1998; Mickleburgh et al., 1992; Utzurrum, 1992) be- cause of both overhunting and destruction of low- land forests. Also included in this category are the long-tailed macaque (Macaca fascicularis), bug- kun {Phloeomys cumingi), Philippine wild pig (Sus philippensis), and Philippine brown deer (Cervus mariannus), all of which have been and continue to be hunted so heavily on the mountain that their populations (especially the deer) are se- verely depleted and local extinction of most of these large mammals seems likely in the near fu- ture (Oliver et al., 1992, 1993a,b). Hunting in the park should be stopped immediately so that the populations may recover. If protection is provid- ed, recovery of the populations seems likely, at which point sustainable hunting along the border of the park might be assured for the future. There was no protection against hunting during our study periods. The fourth category consists of species that ap- pear to survive only in lowland old-growth or good secondary forest, both of which continued to be depleted in most areas on the mountain dur- ing our studies. Such animals as Haplonycteris fischeri, Harpyionycteris whiteheadi, Hipposide- ros obscurus, Megaderma spasma, Harpiocepha- lus harpia, and Philetor brachypterus are wide- spread in the Philippines but are known on Mount Isarog only from lowland forest, which has been reduced to a narrow band of vegetation at the up- per edge of its elevational range. These species are suffering similar habitat reductions elsewhere in the country, making them increasingly vulner- able to the effects of declining population size (in- cluding loss of genetic variability, increasing vul- nerability to disease and climatic perturbations, etc.). This situation points to the loss of lowland forest across the Philippines as the single most serious problem for the protection of biological diversity (Heaney & Regalado, 1998). Because even second-growth lowland forest on Mount Is- arog provided habitat for these species, as well as for such species as Crocidura grayi, Apomys mi- crodon, Phloeomys cumingi, Viverra tangalunga, Sus philippensis, and Cervus mariannus, we rec- ommend that all second-growth lowland forest on Mount Isarog be protected. This lowland forest should be allowed to regenerate with native forest and should not be planted with exotic species of trees such as Gmelina and Eucalyptus. The fifth category includes the species that are endemic to the mountain: Archboldomys luzonen- sis, Chrotomys gonzalesi, and Rhynchomys isa- rogensis. The presence of this many species con- fined to a single mountain is quite extraordinary; generally, only isolated oceanic islands in the Philippines such as Sibuyan and Camiguin have so many unique species because of their historical geological isolation from other land masses (Hea- ney, 1986; Heaney et al., 1997, 1998). Fortunate- ly, all three endemic species occur at the higher elevations on the mountain where habitat distur- bance has been minimal. However, the fact that they occur nowhere else in the world makes them entirely dependent on the continued existence of all remaining old-growth forest on the mountain and justifies the concerns about their status that have been expressed (e.g., Baillie & Groom- bridge, 1996; Heaney & Utzurrum, 1991; Heaney et al., 1997, 1998). This observation points clearly to the need for effective protection of all remain- ing natural habitat in the park to prevent these highly distinctive and appealing creatures from disappearing from the one place where they live. The sixth category consists of the 21 species not listed above that are widespread and believed to have currently stable populations. Although their present status is reason for a sense of relief that not all of the native fauna is endangered, it is not reassuring that fewer than half of 44 species known from the mountain fall into this category. Furthermore, without adequate protection of re- maining forest habitat, it is certain that many ad- ditional species will become threatened in the near future. Further study may alter our estimation of the status of any of the species on Mount Isarog, but the broad results are unlikely to change. It is clear that the remaining forest on Mount Isarog is es- sential to the survival of a remarkable set of spe- cies found nowhere else, that the lowland forest (both old growth and second growth) that now remains in the park is home to a large number of species which are increasingly vulnerable, that overhunting is a severe problem which needs to be reduced immediately, or some of the most ap- pealing species will soon disappear, and that caves in southern Luzon are a resource that has been badly abused, with special measures needed throughout the country to protect this unique eco- system. Conclusions Although each place in the Philippines is unique, it seems that Mount Isarog is a microcosm HEANEY ET AL.: MAMMALIAN DIVERSITY ON MOUNT ISAROG, PHILIPPINES 57 that is representative of many of the patterns that we see in the Philippines as a whole. The moun- tain is volcanic in origin and has been strongly influenced by subduction of the Pacific Plate un- der an island arc that has been one of the most geologically active places on earth. The mammal fauna on the mountain is diverse and is rich in both regional and local endemics at a level that is rarely equaled elsewhere in the world. Changes in habitat along the elevational gradient are associ- ated with profound climatic changes (most re- markable is the increase in rainfall by a factor of five), and a great deal of the mammalian diversity on the mountain is associated with this climatic and habitat diversity. Bats and the nonflying small mammals show opposite trends in diversity and abundance along this elevational gradient, as we have seen elsewhere in the Philippines. Other, less pleasant patterns on Mount Isarog also are representative of the Philippines as a whole (Heaney and Regalado, 1998). The lowland dipterocarp rain forest has been all but entirely destroyed; Mount Isarog retains one of the few patches in southern Luzon, and that exists only as a thin band at the upper edge of its former ele- vational range. We heard chain saws virtually ev- ery day in the park, and the roar of the last of the lowland forest trees as they crashed to the ground. Species that formerly were widespread and abun- dant in the lowland forest are now either uncom- mon or absent from the park; those that lived in caves in the lowlands have been most severely affected. Species in the park that are large enough to be of interest to hunters have been severely overhunted and currently are given no protection. The human hand lies heavily on Mount Isarog. Fortunately, there is some good news as well. Exotic commensal species of small mammals are not successfully invading the park and displacing the native species; where the forest remains, the native species are holding their own. Only three species are believed to be locally extinct; the oth- ers that are locally (or nationally) endangered could probably recover if given an opportunity. Best of all, current community development pro- grams at the border of the park, led by the Hari- bon Foundation, offer the hope of a more stable and perhaps sustainable style of life for the local people (Heaney & Regalado, 1998). In 1996, it was evident that some grasslands were gradually being reforested and that poaching had declined. Moreover, the improving national economy may help to draw people into activities that place less pressure on the land. From the fertile plains of southern Luzon, Mount Isarog rises as a giant green mass, home to most of what remains of the natural heritage of the people of Bicol. Let us hope that it remains green, as a source of clean, clear water, as a site for recreation and learning about nature, and as the last refuge of the native flora and fauna that, like the people, call this their home. Acknowledgments We thank W Asido, A. Batal, R. Buenviaje, D. Destajo, R. Fernandez, S. M. Goodman, F Ju- malon, M. Laranjo, M. Lepiten, A. Manamtam, G. Osea, R. Penas, J. Ramos, D. A. Samson, D. Schmidt, L. Tagat, and E. Tamayo for energetic assistance with the field work and N. Aguilar and B. Hernandez of the University of the Philippines at Los Banos for identification of plant specimens. The Protected Areas and Wildlife Bureau and De- partment of Environment and Natural Resources provided permits, logistical assistance, and en- couragement. We are grateful to Carl Buehler, Jodi Sedlock, and Clara Simpson for preparing the graphs and maps that have added much to the util- ity of this paper. 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