"^ ^^...v^ Jj>' ). P. 3 Mammaiiaii Fauna on tin northern Tip of Sabah, Bornei .^zihiyy Md. Nor SHED BY FIFXD M FIELDIANA Zoology NEW SERIES, NO. 83 The Mammalian Fauna on the Islands at the Northern Tip of Sabah, Borneo Shukor Md. Nor Department of Zoology Field Museum of Natural History Roosevelt Road at Lake Shore Drive Chicago, Illinois 60605 U.S.A. Accepted October 30, 1995 Published April 30, 1996 Publication 1475 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY © 1996 Field Museum of Natural History ISSN 0015-0754 PRINTED IN THE UNITED STATES OF AMERICA Table of Contents Abstract 1 Introduction 1 Geology and Climate 2 Banggi Island 2 Balambangan Island 3 Malawali Island 4 MoUeangen Island 4 General Ecological Background 6 Banggi Island 6 Balambangan Island 7 Malawali Island 8 MoUeangen Island 8 Methods 9 Study Sites 12 Banggi Island 12 Balambangan Island 13 Malawali Island 14 MoUeangen Island 14 Accounts of Species 14 Order Insectivora 14 Family Soricidae— Shrews 14 Order Scandentia 15 Family Tupaiidae— Tree shrews 15 Order Dermoptera 17 Family Cynocephahdae— Flying lemur ... 17 Order Chiroptera 17 Family Pteropodidae— Fruit bats 17 Family Megadermatidae— False vampire bats 20 Family Nycteridae— Hollow-faced bats ..21 Family Rhinolophidae— Horseshoe bats 21 Family Vespertilionidae— Common bats 24 Family Molossidae— Free-tailed bats ... 28 Order Primates 28 Family Lorisidae— Lorises 28 Family Tarsiidae— Tarsiers 28 Family Cercopithecidae— Old World monkeys 29 Order Pholidota 29 Family Manidae— Pangolins 29 Order Rodentia 29 Family Sciuridae— Squirrels 29 Family Muridae— Rats and Mice 32 Order Camivora 37 Family Mustelidae— Weasels and Otters 37 Family Viverridae— Civets 37 Order Artiodactyla 38 Family Suidae— Pigs 38 Family Cervidae— Deer 38 Family Tragulidae— Mouse deer 39 Results and Discussion 39 Inventory of Mammals 39 Trapping, Netting, and Visual Surveys ... 40 Island Biogeography 45 Conclusion 47 Acknowledgments 48 Literature Cited 48 List of Illustrations 1 . Map of Southeast Asia and the northern part of Borneo 3 2. Map of Banggi, Balambangan, Malawa- li, and MoUeangen islands 4 3. View of Banggi Peak (Bukit Senambung) from the west of Banggi Island 5 4. View from top of Banggi Peak at 572 m 6 5. View of trapping Site B2 (Kuak Simpol) from the southeast of Balambangan Island 7 6. Mangrove forest at trapping Site C2 (Paramuan), on Malawali Island 8 7. View of MoUeangen Island from the south 9 8. View of flat coastal area near Karakit, Banggi Island 10 9. View of MoUeangen Island from the southeast 11 10. Cumulative number of species and trap- nights on Banggi, Balambangan, Mala- wali, and MoUeangen islands 44 List of Tables 1 . Total individuals, trap-nights, number of species, and percent trapping success of small mammals caught in the study 12 2. Total trap-nights and net-nights, and percent trapping success of fruit bats caught in the study 12 3. Study sites and dates of visits 13 4. Selected measurements of adult Sorici- dae, Tupaiidae, and Cynocephahdae ... 1 6 5. Selected measurements of adult Ptero- podidae 18 6. Selected measurements of adult Mega- dermatidae and Nycteridae 21 ui 7. Selected measurements of adult Rhino- lophidae 22 8. Selected measurements of adult Vesper- tilionidae 26 9. Selected measurements of adult Pri- mates 28 1 0. Selected measurements of adult Sciuri- dae 30 1 1 . Selected measurements of adult Muri- dae 34 12. Selected measurements of adult Viverri- dae 38 13. Selected measurements of adult Traguli- dae 39 14. Mammal species found on Banggi, Bal- ambangan, Malawali, and Molleangen islands 42 15. Physical characteristics and total num- ber of mammals found on Banggi, Bal- ambangan, Malawali, and Molleangen islands 45 IV The Mammalian Fauna on the Islands at the Northern Tip of Sabah, Borneo Shukor Md. Nor Abstract There are 39, 28, 15, and 1 1 species of mammals known from Banggi, Balambangan, Ma- lawali, and Molleangen islands, respectively. More than 35% of the species on each island are reported here for the first time: 20 from Banggi Island, 1 0 from Balambangan Island, 6 from Malawali Island, and all 1 1 from Molleangen Island. Most of the new records on these four islands are bats of 2 1 species, including a very poorly known insectivorous species {Pipistrellus vordermanni). Others include two primates {Tarsius bancanus and Nycticebus coucang) and three civets {Viverra tangalunga, Paradoxurus hermaphroditus, and Arctogalidia trivirgata). Four insectivorous bats and a Bomean endemic tree squirrel {Exilisciurus exilis) were reported earlier either on Banggi or on Balambangan Island but were not found in this survey, presumably because they occur at very low density. Two species of rats {Rattus tiomanicus and Sundamys muelleri), two fruit bats (Cynopterus brachyotis and Rousettus amplexicaudatus), one ungulate {Sus barbatus), and a primate (Macaca fascicularis) are the most abundant mammalian species on these four islands. There are no conspicuous morphological differences among island pop- ulations, or between them and the adjacent mainland population, except for Sundamys muelleri, from Malawali Island; mean body size in this population is substantially smaller than in other populations. No endemic species are present on these islands, but three species otherwise restricted to Borneo are present on Banggi Island: Tupaia gracilis, Exilisciurus exilis, and Hipposideros dyacorum. In general, the mammalian fauna is shared among the islands and mainland Borneo and exhibits a characteristic feature of land-bridge island faunas: it follows a nested subset pattern that was shaped through selective extinction following the rise in sea level that began about 16,000 years ago. The — 120 m bathymetric line is a boundary line that divides the Bomean fauna of these islands from the Palawan fauna of the Philippine Islands immediately to the north. Introduction The great tropical island of Borneo supports one of the richest mammal faunas on Earth; approx- imately 221 native species have been recorded there. Of these, 92 species are bats (Chiroptera) and 129 species are nonvolant. Nonvolant mam- mals are represented by 8 species of Insectivora, 10 species of Scandentia, 13 species of Primates, 56 species of Rodentia, 26 species of Camivora, 12 species of Artiodactyla, and 1 species each of Dermoptera, Pholidota, Proboscidea, and Peris- sodactyla (Payne et al., 1985). Between 28 and 31 species of mammals are considered to be endemic to Borneo (Davis & Payne, 1982; Payne et al., 1985; Heaney, 1985b, 1986). Of the 22 1 species of native mammals on Bor- neo, at least 160 have been found in Sabah. Of these, 52 species are bats. Among the nonvolant species, 19 are found mainly or only in upland regions and 89 are found mainly or only in the lowlands and low hills; 3 species have been found only on Mt. Kinabalu (Davis & Payne, 1982). Among 29 mammalian families in Sabah, the squirrels (Sciuridae) are the most diverse, with 1 5 genera and 27 species. Sabah's mammals include a number of exceptional species: the world's larg- est tree squirrel (Ratufa affinis), the smallest tree FIELDIANA: ZOOLOGY, N.S., NO. 83, APRIL 30, 1996, PP. 1-51 squirrel {Exilisciurids exilis), the world's largest bats {Pteropus vampyrus), and the largest member of the Insectivora (Echinosorex gymnurus). Although the checklist of mammals that occur on mainland Sabah is now considered to be vir- tually complete (Banks, 1949; Davis, 1962; Med- way, 1977; Davis & Payne, 1982; Payne et al., 1985; but see also Emmons, 1993), little infor- mation has been gathered on the ecology and dis- tribution of mammals from offshore islands. There are more than 20 islands off the north, west, and east coasts of Sabah, but only about 7 of them (Labuan, Tiga, and Gaya islands on the west coast and Banggi, Balambangan, Malawali. and Men- galum islands at the northern tip) have been sur- veyed, none intensively (Chasen & Kloss, 1931; Wells & Lowry, 1975; Medway, 1977; WeUs, 1977; Omar et al., 1984; Pa>Tie et al., 1985). Small nonvolant mammals previously known on these seven offshore islands represent six fam- ilies (Muridae, Sciuridae, Tupaiidae, Soricidae, Cynocephalidae, and Erinaceidae), and large mammals represent four families (Cercopitheci- dae, Suidae, Tragulidae, and Cervidae). Among small mammals, murid rodents are the most di- verse and occur on all islands; at the opposite ex- treme, the erinaceids are represented by a single species found only on Labuan. The two most wide- spread and abundant large mammal species found on most of the offshore islands are wild pig (Sus barbatus) and long-tailed macaque {Macaca fas- cicularis). Two other wild ungulates, deer {Cenus unicolor) and mouse deer {Tragulus napu), are known only from the largest of the offshore islands, Banggi and Balambangan. Out of eight families of bats found on Borneo (Pa>Tie et al., 1985), six have been recorded from offshore islands of Sabah. Prior to this study, com- mon bats (Vespertilionidae) were represented by seven species, followed by fruit bats (Pieropodi- dae) v^ith five species, horseshoe bats (Rhinolo- phidae) with four, sheath-tailed bats (Emballon- uridae) with two. and free-tailed bats (Molossidae) with one species (Chasen & Kloss, 1931; Medway, 1977; Omar et al., 1984; Payne et al., 1985). Bats are considered the most diverse mammals in Bor- neo, but they generally are poorly known. This is probably because many are small, agile, and dif- ficult to catch, requiring special trapping methods (Payne etal., 1985). Unfortunately, habitat destruction on the off- shore islands of Sabah is proceeding ver\ rapidly, due to both selective logging of primary forest and total clearing for agriculture. Because these islands have not been thoroughly sampled and little or no attention was given to them by previous collectors, little faunal information is currently available. Thus, the need to gather information while large areas of primary forest are still intact is of crucial importance. The purpose of my study was twofold: to doc- ument the number of mammals occurring on Banggi, Balambangan, Malawali, and Molleangen islands at the northern tip of Sabah, and to obtain information on their basic ecology. The first three of these islands were surveyed in 1927 by a party from the Raffles Museum of Singapore (Chasen & Kloss, 1931) and later by Wells (1977) and Payne et al. (1985), and the systematics of the mammals was summarized by Medway (1977) and Payne et al. (1985). However, it seemed likely that the sur- veys were incomplete, and ecological information from these three islands and adjacent islands was almost entirely lacking. This monograph reports the results of my survey of the mammals on four offshore islands of Sabah. All known previous records of mammals are in- cluded in this report (Chasen & Kloss, 1931; Wells, 1977; Payne etal., 1985). Because many mammals recorded in this survey had not been reported pre- viously and the general ecology of species had not been documented, I present data on reproduction, description of habitats where animals were taken, and external and cranial measurements whenever possible. Geolog>' and Climate Borneo is the fourth largest island of the world, covering an area of 743,244 km^. The state of Sabah, at the northern tip of Borneo, occupies 76, 1 1 5 km- and is flanked by many offshore is- lands, from the Brunei Bay on the east coast, across the Strait of Balabac at the north, and ending at Sibuko Bay on the west coast (Fig. 1 ). The four study islands, Banggi, Balambangan, Malawali, and Molleangen islands, at the northern tip of Sabah (Figs. 1 and 2), are geologically similar in their formation, consisting of relatively young sediment. Their strata have been dated up to Up- per Cretaceous/Eocene (Wilson, 1 96 1 ). Banggi Island Banggi Island is the largest island along the coast of Sabah, with an area of 450 km*. It is located about 20 km north of mainland Sabah, between HELDIANA: ZOOLOGY 115° 116° 117° 118° 119° Balabac Strait Figure 2 SCALE 0 30 60 90 120 Sulu Sea or 06^ INDONESIA 05^ Celebes Sea Fig. 1 . Map of Southeast Asia and the northern part of Borneo. longitude 1 17°3' and 1 17°25'E and latitude 7°07' and 7°23'N. The island is roughly oval in shape, about 29 km long and 20 km wide. The highest peak, Bukit Senambung, at 572 m, is near the northwest coast. Topographically, areas extending northeastward and southward from Banggi Peak (Bukit Senambung) are slightly hilly, decrease in elevation toward the center of the island, and are still lower farther south and west (Figs. 3 and 4). The south and east coasts of the island are fringed with mangrove forest for most of their length. However, on the north and west coasts there are many sandy beaches, with only a few patches of mangrove forest developed at the mouths of riv- ers. There are few freshwater streams on the island; most are in the north and east, are short, run rap- idly from their source over coarse boulder beds to the sea, and are potentially dry within a few weeks of cessation of rains, usually between May and June. On the east and south are saltwater streams, long and meandering across estuarine swamps. Several small islands surround Banggi, mostly to the east and south, namely Patananum, Paga- san, Balak, Panukaran, Bilangan, Sibogok, Latuan, and Kagayan (Fig. 2). These islands are very low in elevation, and most are covered by mangrove forest (unpublished vegetational map based on 1972 forest inventory by Sabah Forestry Depart- ment). Balambangan Island This island, with an area of 150 km^, lies be- tween longitude 1 16°45' and 1 17°2'E and latitude 6''I0' and 7°25'N, about 5 km west of Banggi Island and 30 km north of the mainland town of Kudat. MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 55* PAGASAN IS. ^^PATANUNAN IS. *^\\PM0(.IEANGEN IS. SCALE 5 KM ' MATI IS. C*r^ 6-> S -. 051 .MAIAWALI^ Fig. 2. Map of Banggi, Balambangan, Malawali, and MoUeangen islands, showing major localities, forest reserves, and other adjacent islands, as mentioned in the text. Localities are indicated by number: 1 , Karakit (Site A4); 2, Wak-wak (Site Al); 3, Lok Tohok (Site A5); 4, Kalangkaman (Site A2); 5, Banggi Peak; 6, Sabor (Site A3); 7, Tanjung Periok; 8, Selamat Darat (Site Bl); 9, Kuak Simpol (Site B2); 10, Paramuan (Site CI); 11, Site C2; 12, Site Dl; and 13, Site D2. It is elongated in a northeasterly direction, is 20 km long, and has an irregular, deeply embayed southeastern coastline. The island is topographi- cally homogeneous at its north and east, with the elevation increasing from its center toward the south. In the south, near Air Simpul (Kuak Sim- pul), the greatest elevation is reached on a 1 34-m peak (Figs. 2 and 5). This peak is flanked by prom- inent limestone cliffs, with a vertical cliff" facing southeast toward Tanjung Kalutan. Most fresh- water streams run from this hill, and most of them run to the south and the east of the island; they are very short and flow directly to the sea. Malawali Island Malawali Island has an area of about 45 km^. It is oval in shaj)e, about 8 km across from east to west, and about 5 km deep. Of the four islands in this study, it is the nearest to the mainland (15 km). It lies at latitude 7°04'N and longitude 1 17°10'E. The shore rises fairly rapidly from the sea, and the coastline is covered mostly by man- grove (Fig. 6). There are two beaches, at Paramuan on the west coast and at Malantak on the southeast coast. The interior is hilly; the highest peak, on the south coast, is 160 m (Fig. 2). MoUeangen Island MoUeangen Island (1 1 7°02'E and 7°05'N) lies at the southern tip of Banggi Island and covers an area of about 1.5 km^. It is about 3 km from Tan- jung Kammaung (on Banggi Island) and 15 km from the mainland. Three-quarters of this island is flat, and only a small portion at the southeast FIELDIANA: ZOOLOGY Fio. 3. View of Banggi Peak (Bukit Senambung) from the west of Banggi Island. At the base of the peak is the trapping Site A2 (Kalangkaman). is slightly elevated, with the highest peak at 120 m (Figs. 2 and 7). Like other islands on the Sunda Shelf, these four islands previously were joined to the mainland and became isolated by rising sea level during the late Pleistocene. Based on the present depth of the sea between the islands and the mainland, I estimate that they were separated from the mainland about 9,000 years ago. This estimation is based on data from Dunn and Dunn (1977) and Fairbanks (1989), who hypothesized that a rapid rise in sea level, from —120 m, occurred beginning about 18,000 BP, to a level within 1 0 to 15 m of present sea level by 6,000 BP; the current sea level was es- tablished in about 2,000 BP (Fairbanks, 1989, Fig. 2). Balambangan, Banggi, Malawali, and Mollean- gen islands lie on a bank less than 35 m deep. Balambangan Island is separated from Tanjung Sempang Mengayau, on the mainland, by a narrow channel 35 m deep. However, the channel is very shallow between this island and Banggi Island, be- ing less than 10 m deep at the northern part. Be- tween Banggi Island and the mainland is a short, narrow basin, running east and west, with a min- imum depth of 35 m, varying between 80 m in the west and 50 m in the east. Malawali Island is nearest to the mainland, separated by a shallow watercourse 18 m deep. Much deeper water (ca. 145 m) separates these islands from the Balabac Islands to the north (U.S. Defense Mapping Agen- cy, scale 1:200,000) (Fig. 2). The climate of the four islands is considered equable. It is controlled by the monsoons; the wet- ter period occurs during the northeast monsoon, from October to February, and the drier season during the southwest monsoon, from March to September. Between monsoons there are periods of variable winds lasting about 6 weeks. During the dry season the islands receive an average rain- fall of 100 to 150 mm. During this period, the northern part of the islands may not receive rain for several weeks, and many of smaller streams dry up. However, during the wettest season, rain- fall may exceed 400 mm per month. The mean annual rainfall over 9 years ( 1 982-1 990) for Kudat District was 2,105 mm (unpublished data from Malaysian Meteorological Service, 1 990). The dai- MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO Fig. 4. View from the top of Banggi Peak at 572 m. On the background, facing to north of the Banggi Island, is the forest, which was selectively logged probably as early as the 1 960s. ly maximum and minimum temperatures rarely exceed 32°C and 20°C, respectively. The atmo- sphere is always damp, with the relative humidity typically above 80%. General Ecological Background Reports on the flora of Banggi, Balambangan, and Malawali islands are those of Omar et al. (1984), Wells (1977), and Merrill (1924, 1926). Omar et al. (1984) also briefly described the hab- itats and the fauna of a few offshore islands of Sabah. Wells (1977) described habitats on Balam- bangan Island in a proposal to declare Balamban- gan Island a national park. Complete vegetational accounts of Banggi and Balambangan islands were compiled by Merrill (1924, 1926). My description of the habitats on these four islands was based on these references, plus records from the Sabah For- estry Department at Kudat, a vegetational map based on a forest inventory made in 1972, and general observations and botanical sampling dur- ing my survey. Banggi Island Most of the southeast coast is covered with man- grove forest, with Rhizophora mucronata as a dominant species. Areas further inland, toward the north and east, are covered with primary to low- land forest comprised of Eugenia sp., Gluta sp., Calophyllum sp., Mangifera caesaria, Dimocarpus lingan, Adinandra sp., Durio grandiflorus, and Shorea spp. (Omar et al., 1984). Most of the pri- mary lowland forest is found within two forest reserves that were gazetted by the Sabah State Government in the early 1960s. The first forest reserve is the Banggi Forest Reserve (Commercial Forest Reserve Class II), located in the northeast portion of the island; it covers an area of about 1 1 ,206 ha. The smaller reserve is the Karakit For- est Reserve (Protected Forest Reserve Class VI) at the southern tip of the island, covering an area of about 24 ha. One mangrove forest reserve (For- est Reserve Class V) also was set aside at the south- east comer of the island, covering an area of about 11,504 ha (unpublished vegetational map based on 1972 forest inventory by Sabah Forestry De- HELDIANA: ZOOLOGY Fig. 5. View of trapping Site B2 (Kuak Simpol) from the southeast of Balambangan Island. On the background is the highest p>eak on Balambangan Island, at 1 34 m, flanked by prominent limestone chffs with large vertical faces. partment; for forest classification see Davis & Payne, 1982). Rapid destruction of forest communities on this island is due primarily to selective logging, clear- cutting for plantation, and shifting cultivation. Logging operations began as early as the 1 960s but stopped after a few years. In 1989 logging opera- tions (selective logging) began in the northwestern region near Banggi Peak and in the southeastern region near Sabor. From this operation at least six species of commercial trees have been extracted from this island, namely Intasia palembanica, Shorea spp., Hopea sangal, Meiogne viregata, Pantacae spp., and Dialium spp. (Sabah Forestry Department, Kudat). At the time of my field sur- vey, the logging operation near Banggi Peak had been terminated. However, the logging operation near Sabor, and cutting of the mangrove forest throughout the island, was still active. Mangrove wood is extracted primarily for wood pilings and woodchips and is one of the major sources of in- come for people on this island other than fishing. Most flat coastal areas have been cleared of pri- mary vegetation for coconut plantations except two or three places north and west of Banggi Peak. Behind the coconut plantations there is a zone of shifting cultivation; this consists of cleared patches planted with tapioca or banana, or patches of sec- ondary forest (belukar) in various stages of re- growth, or areas covered with grass {Imperata cy- lindrica) that have suffered excessive use, leading to soil degradation (Fig. 8). Most of the grasslands are large and liable to bum when there has been no rain for some weeks. Balambangan Island More than 40% of the coastal area is covered by mangrove forest, with Rhizophora mucronata as the dominant species (Sabah Forestry Depart- ment, Vegetational Map, 1972). Mangrove covers coastal areas in the north and southeast. Unlike Banggi, flat coastal areas on this island are not planted with coconut, except for two areas at the most southern tips near Sinai and east near Se- lamat, but rather are cleared for tapioca and ba- nana. Further inland, especially in the east, west, and north, there is evidence of shifting cultivation and human habitation in the past. The worst areas MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO Fig. 6. Mangrove forest at trapping Site C2 (Paramuan) on Malawali Island. As on most of the other islands, cutting of mangrove forest for pilings and woodchips was still active on this island. The mangrove forest at this site had recently been selectively logged, forming a large canopy opening. are near Tanjung Periok in the northeast and Pa- dang in the north, where nothing is visible except open grassland {Imperata cylindrica) with patches of Casuarina nobolis toward the shore. These areas have been major human habitation sites since the 1 770s, when the East India Company Post was set up in 1773. Later, during World War II, it was used as a Japanese Army post (Teo & Sullivan, 1988). Primary lowland forest in the south and center of this island is still intact and dominated by Sho- rea sp., Knema sp., Gluta sp.. Calamus sp., and Gnetum laurifoHum (Omar et al., 1984). Several timber species were removed during a roughly 1-year logging operation in 1989 on the east coast of the island. The commercial timber species have been reported to be the same as on Banggi Island. Only in the southern portion of this island, where disturbance is least, has a forest reserve been cre- ated, the Balambangan Forest Reserve (Forest Re- serve Class III), near Kuak Simpol. This reserve covers an area of about 37 1 ha and includes a small portion of mangrove forest along its eastern edge. Malawali Island On Malawali there is clear zonation of vegeta- tion extending from the shore inland. The majority of Malawali's coastal areas are covered by man- grove, except for two sandy beaches, at Paramuan on the southwest coast and at Matalantak on the east coast. Behind the mangrove forest is a narrow band of native shore flora dominated by Casua- rina nobolis. Inland, there is primary vegetation comprised of Artocarpus sp., Knema sp., and Ar- idisia sp., except near the south coast, where there is open grassland {Imperata cylindrica). There are also patches of rattan {Calamus sp.) shrub in the north and patches of small crawling bamboo (Schi- zostachyum sp.) in the west. Only two species of commercially important trees are found on this island, Dipterocarpus verrutosus and Ceriops tagal. M olleangen Island About 75% of this island is covered by coconut plantation that was begun in the early 1950s. The HELDIANA: ZOOLOGY F Fig. 7. View of Molleangen Island from the south. Note that three-quarters of this island is flat, and only a small portion of the island at the southeast is slightly elevated, with the highest peak at 1 20 m. only forest remaining occupies an elevated area in the southeastern part of the island (Fig. 9). There are no mangrove or commercial timber species found on this island. Tree species are represented by typical secondary forest trees such as Ptero- spermum diversifolium, Mollotus paniculatus, and Polyathia microtus. Methods Banggi, Balambangan, Malawali, and Mollean- gen islands were each visited at least twice within a 5-month period between January and June 1991. Two intensive trapping and netting sessions, at two different sites, and day and night visual sur- veys were made on foot on each island. Trapping and netting were carried out in primary and sec- ondary lowland forest on each island. Day and night visual surveys included most island habitats: primary lowland forest, secondary lowland forest, primary mangrove forest and secondary mangrove forest (except on Molleangen), plantation (e.g., co- conut and tapioca plantation), and grassland (e.g., Imperata cylindrica, except on Molleangen Island, and St aria sp., only on Banggi Island). Trapping, netting, and visual surveying efforts for both vo- lant and nonvolant mammals were similar on each island; on each island, trapping was about 1,000 trap-nights, bat netting was about 45 net-nights, bat trapping with a harp trap was about 7 trap- nights, and day and night surveys were 20-30 hours (Tables 1 and 2). Records of nonvolant small mammals on these four islands were established from trapping with Victor snap traps (ca. 45%), local cage traps (30 X 1 5 X 1 5 cm, ca. 40%). Sherman live traps (ca. 10%), Museum Special snap traps (ca. 4%), and pitfall traps (ca. 1%). Traps (except pitfall traps) were set 25 to 50 traps in a line at 10- to 15-m intervals; about 85% were placed on the ground and 1 5% above ground on fallen logs or large vines. Traps were rebaited every day after dawn and in late afternoon, either with banana or with fresh fried coconut coated with peanut butter (except for a few Museum Special traps, which were baited with either earthworms or grasshoppers). Traps MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO Fig. 8. View of the flat coastal area near Karakit, Banggi Island. Most flat coastal areas on Banggi Island have been cleared for coconut plantations or as a result of shifting cultivation. An area of shifting cultivation is either planted with tapioca or banana, or left unmanaged for several years and replaced by patches of secondary forest (belukar) or grass (Imperata cylindrica). were checked each tnoming soon after dawn and in early evening, and they were run for three to four consecutive nights. Bats were caught in either mist nets or double- bank harp traps (Tuttle, 1974; Tiedmann & Woodside, 1978; Payne etal., 1985; Francis, 1989). Mist nets were set on ridgetops and across trails and streams in primary and secondary lowland forest and in plantations next to forest. They were tended continuously for three to four hours fol- lowing early dusk, then left open until dawn. Nets were run for three to five successive nights at each netting spot. Netting success was calculated based on three consecutive netting nights. Harp traps were used during the second field session and set across small trails or adjacent to small streams in primary and secondary lowland forest. The trap was moved to a different spot each night, and bats were removed only at dawn. In this survey, I caught no fruit bats in the harp trap. One specimen {Ker- ivoula hardwickii) was caught by hand in primary forest on Banggi Island. Diurnal and nocturnal surveys were made on foot over roads, trails, and forest transects of most of the island habitats. The mammal species that are difficult to catch in traps or to identify by sight- ing in the wild, mostly the sciurids (i.e., Ratuffa affinis and Petaurista petauristd), lorises, tarsiers, and deer, were sampled by shooting. About 45% of the specimens of nonvolant mam- mals and 98% of the bat specimens were prepared in fluid and the rest either as skeleton, skull only, or skin with skull. Prepared specimens have been housed at the Zoology Museum, Universiti Ke- bangsaan Malaysia Sabah Campus (ukms), and the Field Museum of Natural History in Chicago (fmnh). External measurements, weights, and reproduc- tive information were gathered in the field on fresh animals. On autopsied animals, testes length and width and embryo length, measured as crown-to- rump length (CRL), were taken. The reproductive status of each specimen was estimated. "Adults" were defined as mature, fully grown, and currently 10 FIELDIANA: ZOOLOGY Fig. 9. View of Molleangen Island from the southeast. This is the only forest remaining on this island. Trapping was done at two sites on this island, Site Dl at the north and Site D2 at the south. or previously breeding individuals with well-de- veloped reproductive organs (nipples or testes). "Subadults" were large young, not fully grown, but in adult pelage. Female subadults were either in estrus or breeding for the first time. The testes of subadult males were smaller than in adult males. "Juveniles" were young, not fully grown, conspic- uously smaller than adult and subadults, dull in pelage coloration, and not showing evidence of breeding (DeBlase & Martin, 1974). Cranial measurements were made on mature/ adult specimens with digital calipers graduated to 0.0 1 mm. Mature/adult specimens were those with fully erupted teeth and well-fused cranial sutures (DeBlase & Martin, 1974). The measurements are defined as follows: condylobasal length, posterior edge of condyle to anterior edge of premaxilla; zygomatic breadth, greatest distance between zy- gomatic arches; interorbital breadth, least distance dorsally between orbits; mastoid breadth, greatest width of skull between mastoid processes; post- orbital width, least distance across top of skull posterior to postorbital process; nasal length, an- teriormost to posteriormost point of nasal bone at midline; nasal breadth, greatest width across nasal bones; rostral length, anterior tip of premaxilla to anteriormost portion of orbit, in the infraorbital foramen; palatal length, posterior base of first in- cisor to posterior edge of palate at midline; palatal breadth at M^, alveolar distance between third up- pcT molars; postorbital length, posteriormost point of orbit or temporal fossa to posteriormost point of occipital bone; rostral depth, least dorso ventral distance from the point where the maxillary-pre- maxillary suture crosses the midline on the ventral surface of the rostrum; molariform toothrow, greatest length of molar toothrow; labial palatal breadth at M', distance between labial edges of first molar; and diastema length, alveolar distance between last incisor present and first cheek tooth present. Identification of each species captured by trap, mist net, or firearm was based on Payne et al. (1985) and Medway (1965, 1977). Comparisons of individual specimens were made at the Field Museum of Natural History, Chicago, and at the Zoology Department, National University of Sin- gapore. MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 11 Table 1 . Total individuals, trap-nights, number of sp)ecies, and percent trapping success of small mammals caught in primary and disturbed forest on Banggi, Bal- ambangan, Malawali, and Molleangen islands from Jan- uary to June 1991. Table 2. Total trap-nights and net-nights, and per- cent netting success of fruit bats on Banggi, Balamban- gan, Malawali, and Molleangen islands from January to June 1991. Netting success was calculated based on three consecutive netting nights. Dis- Balam- Molle- Island Primary turbed Totol Session Bat trap-nights Banggi bangan Malawali angen Total individuals Banggi Island 199 66 265 Session 1 0 0 0 0 Balambangan Island 127 71 198 Session 2 8 7 6 6 Malawali Island 190 39 229 Total 47 45 44 44 Molleangen Island 49 28 77 Net-nights Trap-nights Session 1 10 15 10 19 Banggi Island 765 200 965 Session 2 37 30 34 21 Balambangan Island 778 280 1058 Total 47 45 44 44 Malawali Island Molleangen Island 516 739 424 219 940 954 % Netting success Session 1 12.83 3.17 22.67 6.5 % Trapping success Session 2 3.12 1.44 1.62 4.8 Banggi Island 24.6 31.6 25.9 Total 3.93 5.30 2.13 4.62 Balambangan Island 17.7 22.9 19.0 Malawali Island 25.6 27.8 26.7 Molleangen Island 8.4 15.4 9.7 Number of species Banggi Island 9 9 9 Balambangan Island 9 6 9 done at 10 to 60 m elevation in primary lowland Malawali Island 6 5 6 forest; netting was conducted along the interface Molleangen Island 2 2 2 between prim ary lowland forest and rr langrove Study Sites Two sites were chosen for small mammal trap- ping and bat netting and trapping on each island. The sites were chosen based on the availability of primary forest habitats and the areas most acces- sible either from the sea or by land. The primary focus was to select the area near the highest peak on each island and to include as many habitats as possible. This was crucial, because my primary objective was to obtain the maximum number of mammal species on these islands. The first trap- ping session was carried out during the dry season, between February and mid-April, and was fol- lowed immediately by the second session, which terminated in June 1991. Study sites and the date of visit for each island are summarized in Table 3. Banggi Island Wak-wak (Site A 1 ), an area at the southern lip of Banggi Island (Fig. 2) and part of the Karakit Forest Reserve (24 ha), was visited for 6 days from 8 February to 13 February 1991. Trapping was forest at 10 m elevation. Primary dipterocarp for- est consisted of tall canopy trees ranging from 20 to 25 m in height, with diameter at breast height (DBH) from 0.5 to 0.75 m and moderate buttress development. The forest had a broken canopy at 10-15 m, with the lowest canopy at 10 m. Under- growth was very dense, including saplings, rattans {Calamus spp.), and palms. Moss and canopy ep- iphytes were very uncommon, but woody vines, usually thin and short, were moderately common. The ground was completely covered by leaf litter and several centimeters of humus, thickest at low- er elevations. Large and small carbonate outcrops, and old and new fallen logs of 10-30 cm DBH, were extensively distributed throughout the area, especially at the upper elevations. Abundant large fallen logs implied that occasional heavy wind- storms occurred, possibly during the southeast monsoon. Kalangkaman (Site A2), located southeast of Banggi Peak (Fig. 2), is part of the Banggi Forest Reserve ( 1 1 ,206 ha). It was visited for 7 days, from 26 April to 2 May 1991. Trapping and netting were done in primary forest (ca. 50%), secondary forest that had been logged in the early 1960s (ca. 30%), and coconut plantation (ca. 20%). About 30% of trapping effort in primary forest was concentrated in areas along a shallow river. The primary forest 12 HELDIANA: ZOOLOGY Table 3. Selected study sites and dates of visits on Banggi, Balambangan, Malawali, and Molleangen islands. Island/Site Elevation Date of visit Banggi Wak-wak (Site Al) Kalangkaman (Site A2) Balambangan Selamat Darat (Site Bl) Kuak Simpol (Site B2) Malawali Paramuan (Site C 1 ) Tanjung (Site C2) Molleangen South (Site D2) North (Site Dl) 10-60 m 100-350 m 10-50 m 20-90 m 30-40 m 30-40 m 30 m 30 m 8 to 13 February 1991 26 April to 2 May 1991 8 to 13 March 1991 10 to 16 May 1991 22 to 29 March 1991 24 to 30 May 1991 22 to 28 February 1991 7 to 14 April 1991 trapping and netting were done only between 1 00 and 350 m elevation because the area above 400 m elevation was inaccessible (very steep and cov- ered with huge boulders). Above 350 m, trees were rarely greater than 1 5 m in height, and they were mostly covered by mosses and epiphytes. At the summit, trees were widely spaced, with dense un- derstory vegetation, including grasses, ferns {Dip- teria spp. and Gleichenia spp.), pitcher plants (A^^- penthes spp.), and orchids. Canopy trees in pri- mary dipterocarp forest between 100 and 400 m elevation ranged from 20 to 25 m in height, with DBH from 0.30 m to more than 0.60 m. Most trees were not buttressed, and the canopy was closed. Understory plants and woody vines were uncommon, but mosses and canopy epiphytes were present and extensively distributed on dead wood and live trees. Although selective logging had taken place and forest fires had occurred, the area below 100 m still harbored many large dipterocarps more than 28 m in height and 0.6 m DBH. However, the open canopy allowed extensive growth of un- derstory plants such as figs {Ficus spp.) and ferns. Visual surveys and some hunting were con- ducted at three additional specimen localities on this island. Sabor (Site A3), in the eastern part of the island, included logged forest, with scattered open grassland due to shifting cultivation, and mangrove forest on the coast. Lok Tohok (Site A5), in the southern part of the island and about 3 km north of Wak-wak, was covered with mixed grass and old unmanaged coconut plantations, with scattered remnants of forest trees. Karakit (Site A4) is a small town at the southernmost tip of Banggi Island, about 3 km south of Site A 1 . Sev- eral specimens were collected from nearby man- grove forest. Balambangan Island Selamat Darat (Site Bl), located at the southern end of the island (Fig. 2), was visited from 8 March to 13 March 1991. Small mammals were sampled between 10 and 50 m elevation, with about 65% from secondary forest that had burned in a forest fire during the drought year of 1981 and about 35% from primary forest with little disturbance. Most bat netting was done in the disturbed forest adjacent to primary forest. There were few dip- terocarp trees in this forest. Canopy trees were not more than 20 m in height, with DBH not more than 0.40 m, and most trees were not buttressed. In the understory, saplings 10-30 mm in diameter were abundant, implying that the area may have been disturbed in the past by forest fire. Leaf litter did not completely cover the ground, which was dry, with little humus. In the secondary forest, most trees were figs (Ficus spp.) ranging from 0.2 to 0.3 m DBH, suggesting recent regeneration, with dense ground-level vegetation dominated by grass and ferns. Kuak Simpol (Site B2), located east of Balam- bangan Peak and adjacent to Balambangan Forest Reserve (371 ha) in the southwest (Fig. 2), was visited from 10 May to 16 May 1991. Collecting was conducted between 20 and 90 m elevation in primary forest with little disturbance. The canopy was very dense, with the lower canopy level at 1 0- MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 13 15m. Canopy trees had diameters up to 1 m DBH and ranged from 20 to 25 m in height. Woody vines, some very long and large, and canopy epi- phytes were very common, but mosses were not present. Ground-level vegetation was very sparse. Leaf litter was very thick and covered most of the small carbonate outcrops on the ground. Large carbonate outcrops were distributed sporadically, especially on the hilltops, making it difficult to set traps and nets on a regular transect. Malawali Island A site in the northeast near Tanjung (Site CI) and one in the southwest near Paramuan (Site CI ; Fig. 2) were sampled from 22 March to 29 March 1991 and from 24 May to 30 May 1991, respec- tively. At the southeast site, trapping and mist- netting were done in disturbed forest and old un- managed coconut plantation. However, at the northeast site, small mammals were sampled in primary forest. Two types of habitats can be dis- tinguished in the primary forest: the habitat dom- inated by Casuarina nobolis, with mixed under- story saplings 10-20 mm in diameter, pandan, rattans {Calamus spp.), and climbing bamboo (Schizostachyum spp.), and the habitat in which tall tree species ranged from 1 5 to 20 m in height with DBH from 0.2 to 0.4 m. In the latter habitat, canopy cover was moderately open. There was moderate ground cover of tree saplings, ranging from 15 to 25 cm in diameter, with moderate leaf litter cover and humus layer. Although no one now lives on this island, there is evidence of past hu- man habitation. Present human disturbance on the island was associated with occasional collec- tion of rattan palms and felling of mangrove trees near the trapping sites. Molleangen Island Habitat on this island was fairly homogeneous, consisting of either coconut plantation or primary forest. Small mammals were sampled at a south site (Site D2) from 22 to 28 February 1991 and at a north site (Site Dl) from 7 to 14 April 1991 (Fig. 2). Primary habitat consisted of tall canopy trees, ranging from 15 to 20 m in height and 0.2 to 0.3 m DBH, with moderate buttress development and with a broken canopy at 20-30 m. The understory consisted of small saplings and shrubs, with a thin leaf litter and humus layer. In contrast, the coconut plantation habitat was extensively covered by short grasses and herbaceous dicots. Accounts of Species Order Insectivora Family Soricidae— Shrews Crocidura fuliginosa —The Southeast Asian white-toothed shrew is a poorly known and rarely seen species that has not been previously reported on any offshore island near Borneo (Medway, 1 965, 1977; Payne et al., 1985; Reudi et al., 1 990). How- ever, this species has been taken from five offshore islands near Peninsular Malaysia: Dayang Bun- ting, Tioman, Aur, Redang (Chasen, 1 940; Med- way, 1977), and Singapore (Yang et al., 1990). It is widespread in Southeast Asia and found in a variety of habitats: lightly wooded areas, open grass and scrub, tall coconut plantation, tall secondary and primary forest in lowland and low hill areas, and rocky and mossy forest in montane areas (Thomas, 1889; Banks, 1931; Allen & Coolidge, 1940; Davis, 1962; Lekagul & McNeely, 1977; Medway, 1977; Payne et al., 1985). On 6 March at about 5 p.m. on Balambangan Island, I saw one individual in a small burrow under an old fallen log, in disturbed forest. The log was about 0.35 m in diameter and 2.5 m long, and was lying on the ground about 5 m from and parallel to a small stream. The ground was very damp and sandy, with thick leaf litter and thick humus. Only two specimens were taken on Balamban- gan Island, both at site B 1 : a female was taken in a Victor snap trap set near a dry stream in primary forest, and a male was taken by a domestic cat from a nearby house. The fact that another single specimen was taken by a domestic cat in a house on Tioman Island (Medway, 1966) suggests that the species may at times be associated with human habitation. Although this species was obtained only on Balambangan Island, I suspect that it also ex- isted on the other islands, because little special trapping effort was made to catch insectivores in this survey, with only about 40 to 50 trap-nights (including pitfall traps and Museum Special snap traps) on each island. Three subspecies of C. fuliginosa have been rec- ognized in recent years on mainland Borneo: C. f. foetida in the lowlands, C. / kelabit at the upper elevation in Kelabit upland, and C / baluensis at the higher elevation of Mount Kinabalu (Thomas, 14 HELDIANA: ZOOLOGY 1898a; Medway, 1977; Reudi et al., 1990). Re- cently, C. f. kelabit and C. f. baluensis were sep- arated as a distinct species, C. baluensis (Corbet & Hill, 1992). The present specimens have characteristics of the subspecies C. f. foetida: short gray pelage about 7>-A mm at the middle of the back, and tail 60- 90% of head and body length (Jenkins, 1982; Med- way, 1 977). The other two subspecies, now known as C. baluensis, can be distinguished at once from C.f. foetida by having longer and fluffier back hairs (>8 mm in C. f. baluensis) and having a long tail (equal to or greater than length of head and body) in C / kelabit (Thomas, 1889, 1898a; Lim & Heyneman, 1968; Medway, 1977). External and cranial measurements (Table 4) of single male and female sp)ecimens from Balambangan Island fall at the lower range of a series of C. / foetida and C. / baluensis from mainland Borneo (Payne et al., 1985). Specimens examined— Total 2. Balambangan: Site Bl (2 fmnh). Order Scandentia Family Tupaiidae- -Tree Shrews Tupaia gracilis— The slender tree shrew is an endemic Bomean species, found throughout Bor- neo from lowland forest up to submontane forest and on two offshore islands, Banggi and Karimata (Medway, 1977; Payne et al., 1985; Corbet & Hill, 1 992). Only one adult female was caught on Banggi Island by Chasen and Kloss (193 1). This specimen has characteristics similar to those of the mainland Borneo subspecies, T. g. gracilis, but it differs from T. g. edarata, the subspecies from Karimata Island (Medway, 1965, 1977; Payne et al., 1985; Corbet & Hill, 1992). T. g. gracilis is larger than T. g. edarata, with a hind foot over 40 mm and a slightly larger skull, and it differs in skin coloration, with less russet color present posteriorly on T. g. gracilis (Lyon, 1913). In this survey, two adult males and five females were trapped in primary forest at Site Al on Banggi Island. All specimens were obtained in Victor snap traps baited with fried coconut smeared with peanut butter, set mostly on the ground in primary forest. One adult female cap- tured on 1 1 February had large nipples and one embryo (CRL = 15 mm). External and cranial measurements (Table 4) are similar to those of the specimen collected by Chasen and Kloss (1931) on the same island, and similar to those reported in other series of specimens collected from main- land Borneo (Lyon, 1913; Chasen & Kloss, 1931; Davis, 1958, 1962; Payne et al., 1985; Corbet & Hill, 1992). Specimens examined— Total 7. Banggi: Site Al (7 fmnh). Tupaia minor— The lesser tree shrew inhabits Peninsular Malaysia, Thailand, Borneo, and Su- matra. It is also found on three offshore islands of Borneo: Banggi, Balambangan, and Laut (Med- way, 1977; Payne etal., 1985; Corbet & Hill, 1992). Four specimens from Banggi Island and seven specimens from Balambangan Island were col- lected by Chasen and Kloss (1931). These speci- mens have characteristics of the subspecies T. m. caedis, a race that is confined to the northeastern part of Borneo. These specimens, however, differ from the other mainland subspecies, T. m. minor, by having the upper parts browner and the shoul- der stripe wider and whiter (Chasen & Kloss, 1931; Davis, 1958, 1962; Payne et al., 1985). I took seven specimens at Site A2 on Banggi Island; four were caught in snap traps baited with fried coconut coated with peanut butter and set in primary for- est, and three in cage traps baited with banana and set in disturbed forest and plantations. Another specimen was shot in primary forest near the shore at Site Al on the same island. On Balambangan Island, all nine specimens were taken in cage traps baited with banana and set in disturbed forest at Site B 1 . Two pregnant females and one adult male taken on 1 2 and 1 3 March on Balambangan Island were examined: each female carried two embryos, one in each horn of the uterus. The two sets of embryos had CRL of 26 and 33 mm. A male had testes measuring 10x5 mm. External and cranial measurements of Balambangan and Banggi spec- imens (Table 4) are similar to those of specimens collected from mainland Borneo and from the same islands by Chasen and Kloss (1931), as well as a specimen from Banggi Island reported by Lyon (1913). Specimens examined— Total 17. Banggi: Site A 1 (1 fmnh). Site A2 (3 fmnh, 4 ukms). Balambangan: Site Bl (9 FMNH). Tupaia tana— This large tree shrew is known only from Sumatra, Borneo, and adjacent offshore islands (Medway, 1977; Payne etal., 1985; Corbet & Hill, 1992). Chasen and Kloss (1931) had sam- pled 1 0 individuals from Banggi Island and named them as a new subspecies, T. t. banguei, which is one of 8 subspecies known from Borneo and ad- jacent small islands. Earlier, however, Lyon (1913) referred a single specimen from the same island to T. t. paitana. I took 6 females and 1 3 males on MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 15 a U a 3 c e •o c cd D C/5 C +1 E 4> C 3 « m H) s E H "O M ^ J3 M 4> ^ ♦i* s JS B 4> X lA m t. H e ^ 1^1 o B H ^ z ■2 •A ,2 c« s Cu^ et p ha l( £ 2 h ■fi CS o ^ s es ■fi 6 13) 1 B ■o o ^ 5 » u ct JS s ■o 01 * >> N ^^ A w JB o ^ >> B e o U Z X c^ "O B e« t« I 00 I I I I I I I I I I r^ I v2 c •5 -I E -v ^ •» ^ ^" : ^ ^ O <^ r^ ^ q fo r-; 00 J 00 O i^ o ^ vo vi »«1 Ov f*^ O l~ o OS 00 NO p~' CTn r-! 0\ 1 VO I r-' ■*[--■ f- ~ VO 1^ NO P l~ N f^ Nfi r^ fn (^ m so *'^ NO ''^ •^ O •* ON «s o Tj- o rsi NO o\ w^ On '^^ CO '^ "^ 00 ■^' vO f^ r<^ f^ c^ f«1 ro m w^ — tt .^ ro — NO .^ NO +1 ' - A +1 Jn '^ Jn «*) NO <*> wS bo' 5"P — Tf ''^ +1 T !5 7 +1 7 -j 7 00 C- w ■* C- w r-' — O On 00 — O o O pn 00 o +1 I ;::; I +1 ' ;;; f«1 00 JN - 00 r-^ ^ 00 oo ^ ■*. '^"*'^-: r-" r-~" ''^ NO od O — fN r~~ «^ — •* — ' Tj- t — — -< (SOnoOnOOw^O OO r> Tt — > rr)«/^(^>/^O*0o*<' r~. ri^ (vj f»% 1^ - — !? o r^O'*^^Of^'^NO r^ f^ >n rn r<^ , . . ,- ^. - — >0 f^ •* +1 J^ +1 i 00 ^^ O NO NO NO OO oo 00 c- 3" fN S" ON f? ^ oo 00 c- r- /^ NO "^ o • — u^ "■• NO — 00 ^^ ON ^^ (N "^ NO 00 m). Eonycteris spelaea—The cave nectar bat is a MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 19 widespread species ranging from India east to the Philippines, Sulawesi, and the Lesser Sundas (Koopman, 1989; Corbet & Hill, 1992). This spe- cies has not been reported on any offshore islands of Borneo. I caught most specimens on Banggi and Molleangen islands in disturbed habitat. Three in- dividuals at Site D2 on Molleangen and one in- dividual at Site A3 on Banggi were caught in mist nets set adjacent to clumps of banana (Musa sp.). Another individual was netted in logged forest at Site A2 on Banggi Island. External measurements of Banggi and Molleangen specimens (Table 5) fall within the size range of series from mainland Bor- neo (Chasen, 1931; Hill, 1959; Payne etal., 1985). Condylobasal length and zygomatic breadth are identical to those for a series from Tapadong, Sa- rawak (Chasen, 1931). Specimens examined— Total 7. Banggi: Site Al (1 fmnh). Site A2 (1 fmnh). Molleangen: Site Dl (1 fmnh). Site D2 (3 fmnh, 1 ukms). Macroglossus minimus — The dagger-toothed flower bat is a common, widespread species in Southeast Asia, ranging from Thailand and Viet- nam through Malaysia and Sumatra to the Phil- ippines, the Solomon Islands, and Australia (Koopman, 1989; Corbet & Hill, 1992). M. m. lagochilus is recorded in most areas on mainland Borneo, but it has not been reported on any off"- shore islands. I netted 1 8 individuals on Malawali Island, 5 on Banggi Island, and 2 adult males on Molleangen Island. This species was most com- mon in primary forest at Site A 1 and Site A2 on Banggi Island, and at Site D2 on Molleangen Is- land, but it was common in disturbed forest and banana plantation at Site CI on Malawali Island. External measurements (Table 5) fall within the size range reported by Payne et al. (1985). Specimens examined— Total 17. Banggi: Site A 1 (1 FMNH); Site A2 (4 fmnh). Malawali: Site CI (2 FMNH), Site C2 (8 FMNH). Molleangen: Site D2 (2 fmnh). Pteropus vampynis—T\vt large flying fox is the largest Bomean bat. It is a common, widespread SF)ecies that extends from Tenasserim and Viet- nam to the Lesser Sundas and the Philippines (Koopman, 1989; Corbet & Hill, 1992). P. v. na- tunae is the only subspecies found throughout low- land coastal areas of Borneo, including two off"- shore islands at the north, Banggi and Balamban- gan (Chasen & Kloss, 1931; Payne et al., 1985). Chasen and Kloss (1931) collected one female from Balambangan Island and six juveniles from Banggi Island. I was unable to capture specimens of this species, but I saw a group flying south during a night survey on Balambangan Island near Site B2. According to a local fisherman, there are at least two roosts on Sibogok Island at the east of Banggi Island. Flying foxes on these islands are known to local people as "Kabug" or "Kubong." Rousettus amplexicaudatus —Geof[Toy''s rou- sette has an extensive range from Thailand to the Solomon Islands (Koopman, 1989; Corbet & Hill, 1992). R. a. amplexicaudatus is the only subspe- cies on or near Borneo; it was previously known to roost in caves on the main island of Borneo and Balambangan (Payne et al., 1985). I netted 8 in- dividuals in primary forest on Banggi and Bal- ambangan Island: 5 at Site B2 and 3 at Site A2; and 2 1 individuals were caught in disturbed hab- itats on aU four islands: 2 at Site Al, 6 at Site Bl, 1 at Site CI, 11 at Site Dl, and 1 at Site D2. External measurements (Table 5) are similar to those for a series from mainland Borneo (Chasen, 1931; Medway, 1965, 1977; Payne et al., 1985). Cranial measurements (Table 5) are similar to those for a series from Peninsular Malaysia (Rook- maaker & Bergmans, 1981). Specimens examined— Total 29. Banggi: Site Al (2 fmnh), Site A2 (3 fmnh). Balambangan: Site Bl (1 fmnh, 5 ukms). Site B2 (4 fmnh, 1 ukms). Malawah: Site CI (1 fmnh). Molleangen: Site Dl (10 FMNH, 1 ukms). Site D2 (1 fmnh). Family Megadermatidae— False Vampire Bats Megaderma spas ma— The false vampire bat is a widely distributed species extending from India and Indochina through Sumatra to Java, Sulawesi, and the Philippines (Koopman, 1989; Corbet & Hill, 1 992). In Borneo it has been reported to roost in caves and hollow trees. Two subspecies, M. s. kinabalu and M. s. trifolium, are known on the mainland and on several offshore islands near Bor- neo, and M. s. carimatae has been found only on Karimata Island, off" the east coast of Borneo (Chasen, 1940; Medway, 1965, 1977; Payne et al., 1 985; Corbet &. Hill, 1 992). Two adult males were netted in primary forest at Site B2 on Balamban- gan Island, and four specimens were netted in the understory of primary forest dominated by Ca- suarina nobolis at Site C2 on Malawali Island. External measurements (Table 6) fall within the size range of sp)ecimens from Peninsular Malaysia and Borneo (Payne et al., 1985). There was a total of six specimens examined, from Balambangan, Site B2 (2 fmnh) and Mala- wali, Site C2 (4 fmnh). 20 HELDIANA: ZOOLOGY Family Nycteridae— Hollow-faced Bats Nycteris tragata— The hollow-faced bat is a spe- cies distributed from Burma south to Sumatra and Borneo (Corbet & Hill, 1992). This species pre- viously was recognized as A^. javanica tragata (Chasen, 1940;Medway, 1977; Payne etal., 1985; Corbet & Hill, 1992). This species had not pre- viously been taken from any small offshore island near Borneo (Medway, 1977; Payne et al., 1985; Corbet & Hill, 1 992). A single female was captured in a mist net at Site D 1 on MoUeangen Island. The mist net was set on a small peak in primary forest at about 60 m elevation. External measurements (Table 6) of this specimen fall within the size range of A^. tragata from Peninsular Malaysia (Payne et al., 1985). Cranial measurements (Table 6) of the same specimen are similar to those of a single adult specimen from mainland Borneo (Davis, 1962). Specimens examined— Total 1. MoUeangen: Site Dl (1 FM^fH). Family Rhinolophidae— Horseshoe Bats Hipposideros cervinus—The fawn roundleaf bat is a common, widespread species from Southeast Asia to Australia (Payne et al., 1985; Corbet & Hill, 1992). H. c. labuanensis is the only known subspecies in Borneo. It is a common cave-roost- ing bat in Sabah and Sarawak, and it was known from three offshore islands, Balambangan, La- buan, and Matanani (Medway, 1965, 1977; Payne et al., 1 985). This species has had a confusing tax- onomic history and recently has been split from H. galeritus by Jenkins and Hill (1 98 1). Two spec- imens were captured in a harp trap set in primary forest next to a clump of bamboo at Site A2 on Banggi Island. Nineteen specimens were taken on Balambangan Island: 1 in a mist net set across a shallow stream at Site B 1 and 1 8 in a harp trap in the understory of tall primary forest at Site B2. External measurements (Table 7) of my series from Balambangan Island are similar to those for spec- imens from mainland Borneo (Payne et al., 1985) and from various localities in Peninsular Malay- sia, Borneo, Sumatra, and the Philippines (Jenkins & Hill, 1981). However, two individuals from Banggi Island (Table 7) are slightly larger than the size range given by Payne et al. (1985), but fall within the range of a series reported by Jenkins and Hill (1981). Cranial measurements (Table 7) of bats on both islands are within the range for specimens diagnosed by Jenkins and Hill (1981) as H. cervinus cervinus, except that the average c t =5| Is 'S5 SI >. e I m .1 lo r« *" rri «-) ^ q I ro J, vo >n J^ m o I o I o I r- « vo — ri 00 I o r- I 00 I 00 I ■* o m CTv Ox O _ (^ 00 "0 T "^ 00 ^ O Tt ' o 6 — /S 00 o O 0\ I I I I I I I I I I I I o o f-. I ^ I i:^ I I I I I -: I 09 Family Molossidae— Free-tailed Bats Cheiromeles torquatus— The naked bat is a spe- cies inhabiting Malaysia, Thailand, Sumatra, Bor- neo, Palawan, and smaller nearby islands. It was reported on Banggi Island by Payne et al. (1985). No specimens were caught in this survey. Order Primates Family Lorisidae— Lorises Nycticebus coucang— The distribution of the slow loris extends from eastern India southward to Java and the eastern Philippines (Fooden, 1 99 1 a; Timm & Bimey, 1992). Fooden (1991a) reported that this species is found on small Philippine is- lands off the east coast of Borneo: Tawi-tawi, Si- munul, Bangao, and Sanga-sanga islands. The slow loris in Borneo has been described as TV. c. bor- neanus (Medway, 1965, 1977). My specimen is the first record of this species on smaller islands north of Borneo; a single adult female was shot at Site A3 on Banggi Island, and several other in- dividuals were sighted on the same island. One individual was observed climbing on a small tree at about 8:00 p.m. at Karakit Forest Reserve, and another individual was sighted at 9:00 p.m. on a tree near the main road to Site A4, about 3 km north of Site A 1 . Local people reported that this species can be found throughout the island. Ex- ternal measurements were not taken, but condy- lobasal length and zygomatic width of the adult female specimen (Table 9) are far larger than in a young adult male specimen obtained by Davis (1962) from mainland Borneo. Specimens examined— Total 1. Banggi: Site A3 (1 fmnh). Family Tarsiidae— Tarsiers Tarsius bancanus— The western tarsier previ- ously was known only from Borneo, southern Su- matra, and the nearby islands of Bangka, Kari- mata, Billiton, and Sirhassan (Payne et al., 1985). One adult female, tentatively referred to T. b. ban- canus, is the first record from the offshore islands of Borneo; it was shot during a night survey on 19 June at Site A3 on Banggi Island in old logged forest. During that survey, in the same habitat, three other individuals were sighted. Based on field surveys and reports from natives, the species is found only in the northeastern part of Banggi Is- 28 HELDIANA: ZOOLOGY land, especially in selectively logged habitat and old secondary growth habitat. External measure- ments (Table 9) of a single specimen fall within the size range of those specimens from mainland Borneo reported by Payne et al. (1985), Musser and Dagosto (1987), and Davis (1962). No cranial measurements are available due to the badly dam- aged skull. Specimens examined— Total 1. Banggi: Site A3 (1 fmnh). Family Cercopithecidae— Old World Monkeys Macaca fascicularis— The long- tailed macaque is a widespread species in Southeast Asia, and it is common on offshore islands. This is one of the most abundant large mammal species on offshore islands near Borneo, and it occupies most coastal habitats (Medway, 1965, 1977; Payne etal., 1985). During my field survey, a group of macaques was observed in mangrove forest at Site C2 on Ma- lawali Island. A young adult male macaque was found dead on top of a small ridge at Site Dl near the southeast coast of Molleangen Island, and a group was observed feeding on coconuts at the same site. I saw only one macaque during my sur- vey on Balambangan Island, in mangrove forest at Site B 1 . However, on Banggi Island macaques were very common, not only in mangrove forest, but also in secondary forest and plantations. Chas- en and Kloss (1931) obtained specimens only from Banggi Island. In my recent survey I sampled two specimens from Banggi Island: an adult female was shot about 3—4 km further inland from Site A3 on 1 9 June, and an adult male was shot in mangrove forest at Site A4 on 22 June. External and cranial measurements of these two specimens (Table 9) are almost identical to those of an adult male spec- imen collected by Chasen and Kloss (1931) from Banggi Island and fall within the size range re- ported by Fooden (1991b), Payne et al. (1985), and Davis (1962). Specimens examined— Total 2. Banggi: Site A5 (1 fmnh). Site A3 (1 fmnh). Order Pholidota Family Manidae— Pangolins Manisjavanica— The pangolin or scaly anteater is a species inhabiting Southeast Asia, including some adjacent islands, but not reported on any offshore islands near Borneo (Payne et al., 1985). An individual was observed roaming in selectively logged forest during the field survey on 1 9 June at Site A3 on Banggi Island. Another individual was also reported shot by a hunter at the same area a month before. No specimens are available. Order Rodentia Family Sciuridae— Squirrels Callosciurus prevo5///— Prevost's squirrel is a widespread species from southern Thailand, Pen- insular Malaysia, Sumatra, Singapore, Borneo, and many adjacent small islands (Medway, 1969; Hea- ney, 1978; Yang et al., 1990). Chasen and Kloss (1931) took five specimens each from Banggi Is- land and Balambangan Island. On the basis of skull size, which is slightly smaller than among subspecies from the mainland, Chasen and Kloss (1931) described Banggi and Balambangan spec- imens as separate subspecies, C. prevostii caedis. In this survey, two specimens (one adult male and female) were shot in a coconut plantation near Site Al on Banggi Island. On Balambangan Island, 14 specimens were obtained in live traps at Site B 1 : 6 were caught adjacent to tapioca plantations and 8 in disturbed forest. Based on my field observa- tions, on Banggi Island the species was common in coconut plantations and fringing forest, and on Balambangan Island it was most common in tap- ioca plantations and disturbed habitats. Cranial and external measurements of Banggi and Bal- ambangan specimens (Table 10) are almost iden- tical to those of specimens collected by Chasen and Kloss (1931) from the same islands but slight- ly smaller than those of specimens from mainland Borneo (Chasen & Kloss, 1931; Davis, 1 96 1 ; Hea- ney, 1978; Payne et al., 1985). Specimens examined— Total 16. Banggi: Site Al (2 fmnh). Balambangan: Site B 1 ( 1 0 fmnh, 4 ukms). Callosciurus notatus— Like C. prevostii, the plantain squirrel is also a widespread species on the Sunda Shelf, including small islands such as Singapore, Penang, Tioman, and Perhentian. On small islands near Borneo it is known only on Malawali Island. Chasen and Kloss (1931) col- lected nine specimens from this island and rec- ognized them as a distinct subspecies, C. n. ma- lawali. Nine of my specimens were caught in cage traps set about 1 m above the ground, either on trees or on fallen logs, one in a snap trap set on a tree vine, and three in cage traps set on the ground. MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 29 Table 10. Means (± SD) and ranges of selected measurements of adult Sciuridae. Sample sizes (N) are given separately for cranial and external measurements. Island Sex N Condylobasal length Zygomatic width Mastoid width Rostral length Orbital length Callosciurus prevostii Banggi m 1 — 32.84 — 10.82 15.38 f 1 47.63 32.62 22.77 11.29 16.12 Balambangan m f 3 3 47.49 (47.00-^7.91) 47.77 (46.77-48.57) 31.18 (30.46-31.54) 31.17 (30.39-31.70) 21.40 (20.90-22.05) 21.56 (21.14-21.88) 22.25 (21.91-22.59) 22.35 (21.44-22.90) 15.88 (15.61-16.10) 15.91 (15.34-16.37) Callosciurus notatus Malawali m f 2 1 44.86 (44.49^5.22) 43.82 28.72 (28.33-29.11) 27.96 20.77 (20.41-21.13) 20.24 10.42 (10.40-10.44) 10.36 19.72 (19.48-19.96) 15.04 Petaurista petaurista Banggi m 1 61.77 45.69 31.70 20.09 25.69 f 1 61.88 44.20 32.36 19.96 24.81 Sundasciurus lowii Banggi m Balambangan 1 34.72 22.22 16.43 15.74 12.18 3 34.39 21.64 16.07 15.41 11.58 (32.45-36.25) (20.41-22.72) (15.28-16.98) (14.49-16.63) (11.31-11.93) 2 34.78 22.02 16.44 15.91 12.50 (34.67-34.88) (21.92-22.11) (16.35-16.52) (15.86-15.95) (12.04-12.56) Note: Measurements other than weight are in millimeters. Of these, four were trapped in primary forest, four in an old coconut plantation, and five in disturbed forest. Cranial and external measurements (Table 1 0) are similar to those for specimens from main- land Borneo (Davis, 1962; Payne et al., 1985). However, the condylobasal length is slightly small- er than that of a series of specimens collected by Chasen and Kloss (1931) from the same island. Specimens examined— Total 13. Malawali: Site CI (4 FMNH, 5 UKMs), Site C2 (1 fmnh, 3 ukms). Exilisciurus exilis— The plain pygmy squirrel is known only from mainland Borneo and Banggi Island (Chasen & Kloss, 1931; Heaney, 1985a; Payne et al., 1 985). On mainland Borneo, this spe- cies occurs most often in tall and logged diptero- carp forest; it is recognized as E. e. exilis, differing slightly in coloration from the subspecies E. e. retectus, from Banggi Island (Chasen & Kloss, 1931; Payne et al., 1985). Although Chasen and Kloss (1931) took four specimens, I did not catch or sight any individuals on this island, perhaps because their density is now very low. It is possible that the species is extinct on Banggi Island, but this is unlikely since a large area of primary habitat is still intact on the island. No specimens are available. Petaurista petaurista— The red giant flying squirrel is one of the largest flying squirrels in Bor- neo. It is widespread in Asia, including two small offshore islands near Peninsular Malaysia, Tio- man and Penang (Medway, 1 969), but it has not been reported on any offshore islands near Borneo. Two specimens, one adult male and one adult fe- male, were shot at Site A3 on 19 June, the first records from Banggi Island. This species is very abundant in the northwestern and northeastern portions of Banggi Island. During a night survey on 28 April, I saw nine individuals feeding on wild fig fruit (Ficus microcarpa) at Site A2, and on 19 June I saw two individuals at Site A3. Only cranial measurements (Table 1 0) are available; these mea- surements fall within the size range of two sub- species from mainland Borneo (Payne et al., 1 985), but condylobasal length is smaller than that of two 30 FIELDIANA: ZOOLOGY Table 10. Extended. Molariform toothrow Palatal breadth atM' Diastema length N Total length Tail length Forearm length Weight (g) 7.30 11.74 12.44 _ _ ^ 7.46 12.69 11.96 1 432.0 193.0 53.0 350.0 6.92 (6.88-6.95) 6.99 (6.88-7.30) 12.03 (11.67-12.34) 12.20 (11.88-12.44) 12.22 (12.15-12.32) 12.45 (12.11-12.96) 4 4 413.8 ± 4.8 (408-419) 410.3 ± 9.5 (403-423) 200.8 ± 4.8 (196-206) 196.5 ± 8.6 (191-208) 50.8 ± 1.3 (49-52) 48.8 ± 3.6 (44-52) 275.8 ± 34.0 (260-320) 238.8 ± 18.9 (260-305) 6.05 (6.03-6.06) 6.07 10.79 (10.72-10.85) 10.40 11.89 (11.70-12.08) 11.21 6 4 364.2 ± 6.6 (354-371) 352.0 ± 11.4 (341-365) 174.0 ± 7.9 (161-182) 154.5 ± 15.2 (133-168) 47.7 ± 2.9 (42-50) 44.6 ± 2.9 (41-47) 197.5 ± 17.9 (165-220) 192.5 ± 9.6 (180-200) 10.10 16.27 13.06 - - - — — 9.97 16.94 14.89 __ 5.00 5.20 (5.11-5.35) 4.76 (4.72-4.79) 8.64 8.66 (8.45-9.06) 8.53 (8.51-8.54) 9.74 9.29 (8.95-9.51) 9.65 (9.60-9.70) 1 229.0 4 224.5 ± 17.5 (206-248) 1 208.0 94.0 85.5 ± 10.0 (76-96) 63.0 37.0 34.8 ± 0.5 (34-35) 33.0 80.0 82.0 ± 12.9 (63-91) 80.0 P. p. rajah specimens from Kalabakan, Sabah (Da- vis, 1962). Specimens examined— Total 2. Banggi: Site A4 (2 fmnh). Ratufa affinis— This is the world's largest tree squirrel. It is widely distributed throughout South- east Asia, including several Bomean offshore is- lands: Laut, Penebangan, Sebuku, and Banggi (Medway, 1 977; Payne et al., 1 985). A single adult male was collected by Chasen and Kloss (1931). My survey revealed that they were very abundant in the northwestern and the northeastern parts of Banggi Island; one adult male was shot at Site A3, and several were seen in selectively logged areas at Site A2 feeding on twigs and wild fruits at about 10-15 m from the ground. However, none were observed in the south near the Karakit Forest Re- serve. Only three cranial measurements were taken: rostral length, 25.4 mm; orbital length, 23.7 mm; and diastema length, 14.9 mm; these measure- ments fall within the size range for specimens from mainland Borneo reported by Payne et al. (1985). Because of incomplete cranial and external mea- surements, no comparisons were made to speci- mens collected by Chasen and Kloss (1931) from the same island or from mainland Borneo. How- ever, Chasen and Kloss (1931) suggested that the subspecies R. a. banguei, from Banggi Island, is smaller and has much darker upperparts than the subspecies R. a. sandakanensis, from adjacent mainland Borneo. Specimens examined— Total 1. Banggi: Site A3 (1 fmnh). Sundasciurus lowii— Low's squirrel is known only from Peninsular Malaysia, Sumatra, Borneo, and smaller adjacent islands. This species has been found in tall and secondary lowland forest throughout mainland Borneo, and also in hills up to 1400 m in the Kelabit upland (Lyon, 1911; Gyldenstolpe, 1920; Davis, 1958, 1962; Payne et al., 1985). Two subspecies were distinguished ear- lier from Borneo: S. I. lowii, on mainland Borneo (Thomas, 1 892), and S. I. bangueyae, from Banggi Island (Thomas, 1910). Based on five specimens MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 31 collected from Banggi Island, Chasen and Kloss (1931) concluded that specimens from Banggi Is- land are indistinguishable from the mainland form. I captured two specimens of this species in cage traps set on the ground in disturbed forest at Site Bl on Balambangan Island. Five were obtained on Banggi Island: two in cage traps set on the ground at Site A2 in primary forest and coconut plantation, two in snap traps, and one in a cage trap set on the ground in primary forest at Site B2. Cranial and external measurements of Banggi and Balambangan (Table 10) specimens are similar to those of specimens from mainland Borneo (Tho- mas, 1892; Lyon, 1911; Gyldenstolpe, 1920; Chasen & Kloss, 1931; Davis, 1958, 1962; Payne et al., 1985), but they are slightly larger than those of the series of five specimens from Banggi Island collected by Chasen and KJoss (1931). Specimens examined— Total 7. Banggi: Site Al (2 FMNH, 1 UKMS), Site A2 (2 FMhfH). Balambangan: Site Bl (2 FMhfH). Family Muridae— Rats and Mice Maxomys surifer— The red spiny rat is a com- mon species on both large and small islands in Southeast Asia, including small islands off the north, south, and west coasts of Borneo. Speci- mens of this rat from Banggi, Balambangan, and Malawali islands were originally referred to the name Rattus {Maxomys) panglima by Chasen and Kloss (1931). Medway (1977) pointed out that they are members of the species Maxomys surifer, this was confirmed by Musser et al. (1979). The use of the name Maxomys surifer panglima by Payne et al. (1985) is in error. Rats from Banggi, Balam- bangan, and Malawali islands have slightly darker coloration and a shorter tail than the subspecies from mainland Borneo, M. s. bendahara. On mainland Borneo, this species is found in forest, grassland, and rice fields (Musser et al., 1981; Payne et al., 1985). I found this species most often in primary forest; three out of six specimens were taken in primary forest on Malawali Island, 34 specimens in primary forest and six in disturbed forest on Banggi Island, and 30 in primary forest and 1 2 in disturbed forest on Balambangan Island. On Banggi and Balambangan islands, they were most often caught in snap traps, whereas all six individuals from Malawali were caught in cage traps. At Site A2 on Banggi Island, they were most abundant on high ground above 100 m elevation. On Banggi Peak above 350 m, 20 trap-nights with Victor snap traps caught six individuals. On Bal- ambangan Island at Site Bl between 8 and 13 March, one subadult male had testes measuring 15x6 mm, and four adult males had testes mea- suring 19 X 9, 21 X 9, 19 X 7, and 23 x H mm. At Site B2 between 10 and 16 May, three adult males had testes measuring 28 x 16, 24 x 10, and 18x12 mm, two subadult males had testes mea- suring 18x9 and 22 x 15 mm, and one female carried three embryos measuring 6, 4, and 4 mm CRL. On Banggi, one adult male taken on 29 April at Site A2 had testes measuring 26 x 13 mm. External and cranial measurements of Banggi, Bal- ambangan, and Malawali specimens (Table 1 1 ) are similar to those of specimens from mainland Bor- neo (Davis, 1962; Medway, 1977; Payne et al., 1985) and identical to those of a series from the same islands collected by Chasen and Kloss (1931). Specimens examined— Total 79. Banggi: Site Al (5 FMNH, 5 UKMs), Site A2 (17 fmnh, 3 ukms). Balambangan: Site Bl (32 fmnh, 10 ukms). Site B2 (I fmnh). Malawali: Site CI (1 fmnh, 2 ukms), Site C2 (2 FMNH, 1 ukms). Maxomys w/z//e/zea^/— Whitehead's rat is a spe- cies confined to Thailand, Peninsular Malaysia, Sumatra, Borneo, and adjacent islands, including Banggi, Balambangan, Malawali, and Miang Besar (Medway, 1977; Payne et al., 1985). Two subspe- cies are known in Borneo: M. w. whiteheadi, found throughout the area on mainland Borneo, includ- ing Mt. Kinabalu up to 2 1 00 m, and M. w. piratae, found only on Banggi, Balambangan. and Mala- wali islands (Payne et al., 1985). External and cra- nial variation among island populations {M. w. piratae) is discussed by Corbet and Hill (1992). Previous collectors obtained seven M. w. piratae specimens from Banggi Island, nine from Bal- ambangan Island, and four from Malawali Island (Chasen & Kloss, 1931; Medway, 1 965, 1 977). My survey indicated that this is the most abundant small, nonvolant mammal on the three islands; 146 individuals were taken on Malawali Island (out of a total of 229 individuals of all species), 51 on Balambangan Island (out of 198 total), and 60 on Banggi Island (out of 265 total) (Table 1). However, none were taken on Molleangen Island. On Malawali Island, between 24 March and 1 April at Site CI, one adult female had one embryo mea- suring 25 mm CRL, and two adult males had testes measuring 23 x 12 and 20 x 10 mm; between 25 and 29 May at Site C2, three adult males had testes measuring 18 x 12, 17 x 10, and 20 x 10 mm. Five adult males taken between 8 and 1 3 March at Site B 1 on Balambangan Island had testes rang- 32 RELDIANA: ZOOLOGY ing between 14 x 9 and 22 x 13 mm, and one subadult male had testes measuring 15x7 mm. On the same island between 10 and 16 May at Site B2, two males had testes measuring 20 x 10 and 16x11 mm. External and cranial measure- ments (Table 1 1 ) are within the range of several series from mainland Borneo (Lyon, 1911; Gyld- enstolpe, 1 920; Chasen & Kloss, 1931; Davis, 1 962; Payne et al., 1985) and identical to those of spec- imens collected by Chasen and Kloss (1931) from the same islands. However, the external measure- ments of these specimens (Table 11) are slightly larger than those of a pair collected from Mt. Kin- abalu (Thomas, 1894). Specimens examined— Total 255. Banggi: Site Al (13FMNH, 11 UKMS), Site A2 ( 1 5 FMNH, 8 UKMS). Balambangan: Site Bl (19 fmnh, 14 ukms). Site B2 (16 FMNH, 7 ukms). Malawali: Site CI (49 fmnh, 28 ukms). Site C2 (59 fmnh, 16 ukms). Niviventer cremoriventer— The dark-tailed tree rat is a widespread species, inhabiting areas from Burma south to Java and Borneo (Musser, 1973; Payne et al., 1985). It is also found on offshore islands near Peninsular Malaysia (Penang, Lang- kawi, and Tioman) and Borneo (Banggi, Balam- bangan, and Malawali) (Medway, 1965, 1977; Musser, 1981). Chasen and Kloss (1931) caught four specimens on Banggi Island, two on Balam- bangan Island, and three on Malawali Island and designated them as N. c. malawali, distinct from the mainland race, A^. c. kina. Medway (1965, 1977) and Payne et al. (1985) also considered these two subspecies to be distinguishable, with the island race duller in color than the mainland race. How- ever, on the basis of external and cranial mea- surements, Musser (1973) concluded that speci- mens from mainland Sabah are indistinguishable from the island race. On mainland Borneo, this species has been reported from a variety of hab- itats, but I found most individuals in primary for- est at my sites on Banggi, Balambangan, and Ma- lawali islands. On Malawali Island at Site CI be- tween 24 March and 1 April, one subadult and one adult female each had one fetus measuring 25 and 23 mm CRL, and four adult males had testes measuring 12 x 9, 13 x 8, 14 x 8, and 14 x 8 mm. One adult male from Site Bl on Balamban- gan Island on 9 March and one adult male from Site A2 on Banggi Island on 28 April had testes measuring 17x7 and 15x7 mm, respectively. External and cranial measurements of Banggi, Bal- ambangan, and Malawali specimens (Table 1 1 ) are slightly larger than those of specimens from main- land Borneo (Chasen & Kloss, 1931; Musser, 1973; Payne et al., 1985), but they are slightly smaller than those of a series from the same islands col- lected by Chasen and Kloss (1931). Further, ex- ternal and cranial measurements of the specimens from Banggi Island are slightly larger than those of series from Balambangan and Malawali islands. Specimens examined— Total 60. Banggi: Site A I (6 fmnh, 6 ukms). Site A2 (4 fmnh, 1 ukms). Bal- ambangan: Site Bl (5 FMNH, 3 ukms). Site B2 (6 FMNH). Malawali: Site CI (6 fmnh, 7 ukms). Site C2 ( 1 1 FMNH, 5 ukms). Rattus tanezumi diardii— The house rat is a common and worldwide commensal species. Medway and Yong (1976) and Musser and Califia (1 982) considered this rat to have been introduced to the Sunda Shelf from an unknown area outside this region. In using the name Rattus tanezumi, I follow Musser and Carleton ( 1 993), who have split this species from Rattus rattus. I caught two spec- imens at Site A2 on Banggi Island in live traps baited with banana set in a coconut plantation about 1 00-200 m from houses. I found field iden- tification of this species to be difficult; individuals had light brown upperparts with milky white un- derparts, characteristic of/?, tiomanicus jalorensis as described by Medway ( 1 969), Payne et al. (1985), and Musser and Califia (1982). However, external measurements (Table 1 1 ) are larger than those of R. tiomanicus from the same island, but they fall within the range of R. tanezumi from mainland Borneo (Payne et al., 1 985). Cranial measurements of both male and female specimens fall within the range of those of six adult R. tanezumi specimens from various localities on mainland Borneo that are available in the fmnh collection, but they differ from those of/?, tiomanicus from Borneo. Cranial measurements of these specimens are identical to those reported for R. tanezumi diardii (Medway, 1966; Musser & Califia, 1982). Specimens examined— Total 2. Banggi: Site A2 (2 fmnh). Rattus tiomanicus— The Malaysian field rat is widely distributed in the area of Peninsular Ma- laysia, Sumatra, Java, and Borneo, including off- shore islands at the north, east, south, and west (Medway, 1977; Musser &. Califia, 1982; Payne et al., 1985). Four subspecies can be distinguished, based on underpart coloration and skull measure- ments: R. t. sabae, widespread throughout Sabah, northern Sarawak, and part of East Kalimantan; R. t. jalorensis, recorded from Sarawak as far north as the Baram and part of east and west Kaliman- tan; R. t. banguei, known only on Banggi and Ma- lawali islands; and R. t. mara, known only from MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 33 Table 1 1. Means (± SD) and ranges of selected measurements of adult Muridae. Sample sizes (N) are given separately for cranial and external measurements. Condylobasal Zygomatic Island Sex N length width Mastoid width Rostral length Orbital length Maxomys surifer Banggi m 3 40.55 19.71 15.26 18.01 13.49 (36.96^2.94) (17.71-20.88) (14.30-16.12) (15.58-19.61) (12.57-13.97) f 3 39.07 18.60 14.72 17.18 13.03 (38.08-40.42) (18.18-19.03) (14.67-14.79) (16.98-17.35) (12.76-13.31) Balambangan m 4 41.47 ± 2.13 19.72 ± 1.16 14.96 ± 0.37 17.95 ± 1.17 13.57 ± 0.86 (38.80-43.98) (18.10-20.68) (14.83-15.44) (16.39-19.02) (12.30-14.20) f 2 39.70 19.00 14.37 17.92 13.08 (36.85-42.54) (18.19-19.88) (14.22-14.51) (16.80-19.04) (12.42-13.74) Malawali m 2 35.51 18.64 14.59 16.45 12.12 (33.00-38.01) (18.46-18.82) (14.55-14.63) (16.16-16.73) (11.94-12.31) f 1 37.55 18.92 13.95 16.66 12.55 Maxomys whiteheadi Banggi m 5 30.44 ± 1.73 14.97 ± 0.38 12.51 ± 0.28 12.80 ± 1.07 10.77 ± 0.54 (28.75-33.14) (14.54-15.43) (12.24-12.86) (11.76-14.54) (10.34-11.58) f I 30.06 15.22 12.43 12.54 10.10 Balambangan m 2 30.64 15.60 12.68 12.49 1045 (29.20-32.07) (14.92-16.28) (12.33-13.03) (11.93-13.05) (10.37-10.52) f 3 30.46 15.10 12.58 13.09 10.46 (29.88-31.08) (14.80-15.64) (12.36-12.70) (12.81-13.46) (10.16-10.90) Malawali m 4 31.21 ± 0.23 15.23 ± 0.25 12.45 ± 0.26 12.69 ± 0.26 10.55 ± 0.37 (30.90-31.40) (14.89-15.44) (12.21-12.82) (12.32-12.95) (10.24-11.09) f 5 30.35 ± 0.62 15.31 ± 0.44 12.32 ± 0.39 12.44 ± 0.37 10.52 ± 0.33 (29.68-31.36) (14.79-15.97) (11.71-12.64) (12.09-13.08) (10.20-10.84) Niviventer cremoriventer Banggi m 5 31.24 ± 0.59 15.49 ± 0.18 12.85 ± 0.31 12.55 ± 0.53 11.34 ± 0.23 (30.34-31.83) (15.33-15.69) (12.52-13.30) (11.81-12.80) (11.06-11.66) f 2 29.36 15.10 12.80 12.01 10.85 (28.83-29.88) (15.04-15.15) (12.62-12.97) (11.91-12.10) (10.71-10.99) Balambangan m 5 33.41 ± 1.30 17.01 ± 0.89 13.64 ± 0.36 13.72 ± 045 11.83 ± 0.45 (31.26-34.53) (15.58-17.92) (13.01-13.91) (12.92-13.96) (11.22-12.33) f 4 32.53 ± 1.41 16.52 ± 0.79 13.15 ± 0.31 13.59 ± 1.02 11.71 ± 0.24 (30.75-34.17) (15.60-17.51) (13.02-13.61) (12.53-14.98) (11.50-11.98) Malawali m 5 33.73 ± 0.90 16.95 ± 0.13 13.31 ± 0.26 13.44 ± 1.86 11.49 ± 0.19 (32.28-34.40) (16.79-17.14) (12.96-13.61) (13.38-14.78) (11.24-11.72) f 5 32.43 ± 1.19 16.54 ± 0.40 12.95 ± 0.25 1341 ± 0.64 11.22 ±0.35 (30.45-33.39) (15.92-16.93) (12.74-13.36) (12.41-14.01) (10.64-11.53) Rattus tanezumi diardii Banggi m 1 37.80 17.67 15.31 14.15 13.92 f 1 37.03 17.59 14.57 13.71 13.28 Rattus tiomanicm Banggi m 1 — 18.51 — 14.05 13.92 Balambangan f — Malawali m 1 f 2 39.11 42.90 (42.60-43.19) 19.53 20.69 (20.28-21.10) 16.15 16.16 (16.01-17.19) 14.78 16.12 (15.60-16.64) 14.40 15.28 (15.20-15.35) 34 HELDIANA: ZOOLOGY Table 1 1 . Extended. Molariform Palatal breadth toothrow atM' Diastema length N Total length Tail length Forearm length Weight (g) 6.59 7.72 12.52 17 353.5 ± 29.5 173.1 ± 14.5 39.1 ± 2.5 138.7 ± 36.6 (6.41-6.82) (7.09-8.07) (10.73-13.43) (309-399) (154-200) (32-t3) (97-205) 6.52 7.67 12.01 5 347.2 ± 36.7 172.0 ± 15.0 39.2 ± 1.6 125.8 ± 26.1 (6.35-6.61) (7.35-7.84) (11.77-12.31) (305-391) (149-188) (37-il) (85-155) 6.65 ± 0.12 7.86 ± 0.25 12.54 ± 0.97 11 345.4 ± 17.0 168.1 ± 7.2 40.2 ± 1.4 165.0 ± 27.3 (6.48-6.76) (7.64-8.10) (11.18-13.48) (324-374) (160-182) (38^3) (130-210) 6.31 7.79 12.35 4 347.5 ± 18.5 164.8 ± 6.8 37.5 ± 3.0 143.8 ± 33.3 (6.22-6.40) (7.50-8.08) (11.42-13.28) (330-372) (158-174) (33-39) (115-190) 6.31 7.74 11.17 4 322.8 ± 12.9 158.8 ± 6.3 38.8 ± 1.3 120.8 ± 22.0 (6.21-6.41) (7.72-7.75) (10.74-11.59) (309-339) (154-168) (37^0) (100-149) 5.86 7.53 11.46 1 351.0 163.0 37.0 140.0 5.54 ± 0.26 5.89 ± 0.22 8.67 ± 0.49 10 230.4 ± 14.2 100.8 ± 5.8 28.1 ± 1.7 52.3 ± 9.2 (5.33-5.96) (5.54-6.15) (8.20-9.45) (214-251) (91-111) (26-31) (42-65) 5.74 5.97 8.19 10 227.2 ± 14.4 101.0 ± 14.2 27.6 ± 0.7 51.9 ± 8.1 — — — (203-239) (96-124) (27-29) (41-63) 5.42 6.27 8.86 10 241.5 ± 13.9 106.3 ± 9.2 28.2 ± 1.5 74.3 ± 9.7 (5.36-5.47) (6.01-6.52) (8.18-9.53) (220-259) (92-123) (26-31) (62-90) 5.54 6.07 8.40 8 239.9 ± 17.7 108.9 ± 9.0 27.4 ± 1.7 62.4 ± 8.8 (5.45-5.66) (5.96-6.27) (7.60-8.95) (209-257) (98-123) (26-31) (50-74) 5.76 ± 0.17 5.97 ± 0.13 8.82 ± 0.14 10 244.4 ± 12.6 107.0 ± 6.9 28.4 ± 1.4 67.7 ± 9.3 (5.53-5.92) (5.81-6.08) (8.68-8.95) (227-254) (101-118) (27-31) (49-80) 5.67 ± 0.22 6.02 ± 0.10 8.66 ± 0.35 10 215.3 ± 12.4 88.2 ± 30.5 26.7 ± 10.6 47.6 ± 8.4 (5.49-6.03) (5.92-6.15) (8.40-9.25) (198-232) (87-105) (25-28) (33-59) 6.01 ± 0.08 6.17 ± 0.12 8.84 ± 0.38 6 323 ± 9.4 184.7 ± 11.1 27.7 ± 1.0 70.2 ± 5.4 (5.90-6.10) (5.99-6.31) (8.30-9.24) (312-339) (173-201) (26-29) (60-75) 6.04 6.17 8.46 4 294.5 ± 10.5 166.8 ± 6.6 27.0 ± 1.4 50.5 ± 6.6 (5.99-6.08) (6.13-6.21) (8.43-8.48) (283-308) (161-175) (26-29) (42-75) 6.27 ± 0.20 6.66 ±0.13 9.76 ± 0.74 4 368.0 ± 20.2 211.8 ± 8.8 29.8 ± 1.9 83.8 ± 11.6 (5.96-6.46) (6.55-6.83) (8.50-10.41) (344-394) (204-224) (27-31) (69-94) 6.10 ± 0.13 6.67 ± 0.20 9.37 ± 0.74 4 351.3 ± 21.2 203.3 ± 12.0 29.8 ± 1.5 73.3 ± 8.2 (5.90-6.20) (6.48-6.91) (8.50-10.31) (328-373) (191-214) (28-31) (63-83) 6.40 ±0.13 6.46 ±0.12 9.61 ± 0.47 8 348.5 ± 21.5 197.9 ± 19.8 29.8 ± 1.0 81.6 ± 15.9 (6.19-6.55) (6.34-6.63) (8.91-10.03) (312-368) (157-216) (29-32) (50-91) 6.27 ± 0.14 6.43 ±0.15 9.07 ± 0.57 10 335.2 ± 27.7 193.1 ± 17.2 29.0 ± 3.1 71.8 ± 13.7 (6.13-6.50) (6.20-6.61) (8.39-9.77) (303-348) (171-229) (26-37) (54-95) 6.79 7.11 11.32 1 322.0 168.0 32.0 92.0 6.53 6.90 10.89 1 321.0 155.0 33.0 82.0 6.92 7.02 10.97 1 374.0 196.0 35.0 150.0 - - - 1 389.0 194.0 37.0 160.0 6.65 7.66 11.49 1 371.0 198.0 39.0 110.0 7.32 7.91 12.32 4 361.5 ± 45.2 186.3 ± 32.9 37.5 ± 2.5 142.5 ± 35.9 (7.20-7.44) (7.69-8.13) (11.94-12.70) (299-391) (140-215) (34-^0) (110-190) (cont.) MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 35 Table 1 1 . Continued. Condylobasal Zygomatic IsUnd Sex N length width Mastoid width Rostral length Orbital length Molleangen m 5 38.94 ± 2.97 18.51 ± 1.12 15.64 ± 0.67 14.72 ± 1.47 14.09 ± 1.27 (34.99^2.24) (16.91-19.95) (14.88-16.61) (13.12-16.36) (12.30-15.47) f 2 37.36 19.06 15.46 14.38 13.76 (33.53-41.18) (16.90-21.22) (14.51-16.41) (12.95-15.81) (12.10-15.42) Sundamys muelleri Banggi m 4 48.65 ± 1.80 25.06 ± 0.65 19.18 ± 0.69 20.28 ±1.10 17.84 ± 1.05 (47.09-50.44) (24.29-25.83) (18.31-19.87) (19.11-21.28) (16.84-19.31) f 5 48.80 ± 1.59 25.33 ± 0.82 18.93 ± 0.49 20.41 ± 1.02 17.76 ± 0.93 (46.73-49.71) (24.89-25.69) (18.17-19.11) (19.20-22.14) (17.12-18.63) Balambangan m 4 44.49 ± 1.48 23.72 ± 1.17 17.58 ± 0.69 18.05 ± 0.71 17.00 ± 0.50 (42.37^5.14) (22.48-25.24) (16.96-18.43) (16.99-18.48) (16.42-17.64) f 5 45.38 ± 2.78 24.02 ± 1.36 17.80 ± 1.00 17.56 ± 1.88 17.20 ± 1.15 (42.16-48.98) (22.55-25.57) (16.35-18.73) (14.88-18.88) (16.07-18.80) Mala wall m 2 38.50 21.16 15.49 14.98 14.42 (37.55-39.45) (20.83-21.48) (15.27-15.71) (14.10-15.86) (14.16-14.68) f 5 39.38 ± 1.48 21.48 ± 0.85 15.89 ± 0.40 15.97 ± 0.66 14.98 ± 0.63 (37.32^0.98) (20.35-22.26) (15.29-16.34) (15.31-16.60) (14.13-15.58) Molleangen m 2 47.44 25.35 18.74 19.51 17.98 (43.74-51.13) (24.00-26.69) (18.09-19.39) (17.68-21.33) (17.03-18.93) f 6 47.00 ± 1.59 24.75 ± 0.56 18.50 ± 0.64 18.87 ± 1.01 17.93 ± 0.51 (43.91-48.41) (24.21-25.45) (17.60-19.12) (17.12-20.10) (17.07-18.47) Note: Measurements other than weight are in millimeters. Maratua Archipelago off eastern Borneo (Medway, 1977; Musser & Califia, 1982; Payne et al., 1985). Chasen and KJoss (1931) obtained five specimens firom Banggi Island and one adult male on Ma- lawali Island. These sp)ecimens were initially iden- tified as Rattus rattus banguei by Chasen and Kloss (1931), but they were assigned to Rattus tioman- icus when that SF>ecies was recognized as distinct firom Rattus rattus (Davis, 1962; Medway, 1977). R. tiomanicus can be distinguished fi^om Rattus tanezumi (formerly part of R. rattus) based on pelage, which is more sleek over the upperparts, and by relatively short incisive foramina, short maxillary toothrows, and weakly developed su- praorbital ridges compared to R. tanezumi (Med- way & Lim, 1966; Musser &. Cahfia, 1982). Ma- la wali specimens, taken between 24 and 28 March at Site C 1 , included a female with one fetus mea- suring 25 mm CRL and an adult male with testes measuring 13x10 mm, and from Site C2 between 25 and 29 May, an adult male with testes mea- suring 18x10 mm. Three adult males taken be- tween 8 and 1 3 April at Site D2 on Molleangen Island had testes measuring 17 x 15, 25 x 16, and 25x16 mm, and one juvenile male from Site Dl had testes measuring 8x5 mm. External and cranial measurements of single specimens from Banggi and Balambangan islands and the means of specimens from Molleangen and Mala wali (Ta- ble 1 1) are slightly greater than those of specimens from mainland Borneo (Medway, 1 977; Musser & Cahfia, 1982; Payne et al., 1985). Specimens examined— Total 57. Banggi: Site A2 (1 fmnh). Balambangan: Site B2 (1 fmnh). Ma- lawali: Site C 1 ( 1 2 fmnh, 3 ukms). Site C2 (4 FMhfH, 1 ukms). Molleangen: Site Dl (22 fmnh, 4 ukms). Site D2 (6 fmnh, 3 ukms). Sundamys muelleri— 'MuWefs rat is one of the largest rat species in Borneo. It is distributed throughout Southeast Asia, and near Borneo it is present on many offshore islands off the west and southeast coasts, including Lamukotan and Se- buku (Medway, 1977; Musser & Newcomb, 1983; Payne et al., 1985). Chasen and Kloss (1931) col- lected 1 1 specimens on Banggi Island and five on Balambangan Island. I caught this species on Banggi, Balambangan, and Malawali islands, mostly in primary forest on low ground and near streams. On Molleangen Island, four specimens were taken between 8 and 1 3 April from Site D2; two adult males and one subadult male had testes measuring 23 x 22, 25 x 14, and 14x6 mm, respectively, and one adult female had five em- bryos of 43, 40, 43, 44, and 52 mm CRL. On Balambangan Island, one adult male taken on 1 1 March at Site Bl had testes measuring 19 x 7 36 FIELDIANA: ZOOLOGY Table 1 1 . Extended. Continued. Molariform Palatal breadth toothrow atM^ Diastema length N Total length Tail length Forearm length Weight (g) 6.87 ± 0.26 7.23 ± 0.32 11.43 ± 1.08 9 352.9 ± 28.5 176.9 ± 28.2 36.8 ± 1.9 150.6 ± 21.3 (6.67-7.32) (6.89-7.63) (9.86-12.48) (319-391) (118-215) (35^1) (120-195) 6.95 7.28 10.41 2 357.5 199.5 35.5 172.0 (6.34-7.55) (6.75-7.80) (9.52-11.30) (308^07) (171-228) (34-37) (154-190) 9.64 ± 0.47 9.44 ± 0.32 14.35 ± 0.57 10 478.2 ± 21.7 270.0 ± 37.5 46.9 ± 2.1 244.0 ± 54.0 (9.09-10.18) (9.06-9.81) (13.73-14.85) (456-524) (249-275) (45-^9) (150-300) 9.81 ± 0.55 9.45 ± 0.27 14.37 ± 0.49 10 460.0 ± 26.1 244.1 ± 18.6 46.0 ± 3.1 232.5 ± 21.3 (9.47-9.93) (9.24-9.73) (12.96-14.83) (427^98) (215-267) (38^9) (200-260) 9.09 ± 0.26 8.95 ± 0.22 13.02 ± 0.59 10 448.8 ± 26.8 229.5 ± 17.3 42.7 ± 1.4 219.0 ± 59.7 (8.83-9.39) (8.75-9.25) (12.32-13.75) (408^98) (205-264) (40-45) (120-310) 9.04 ± 0.36 9.08 ± 0.64 13.37 ± 0.96 10 430.6 ± 23.5 219.8 ± 11.2 42.1 ± 20.1 208.5 ± 36.3 (8.49-9.44) (8.02-9.76) (11.89-14.24) (387^61) (201-231) (38^4) (125-250) 8.56 8.28 10.97 2 345.0 175.5 39.0 113.0 (8.39-8.73) (8.22-8.33) (10.84-11.09) (342-348) (155-196) (37^1) (96-130) 8.37 ± 0.12 8.24 ± 0.18 11.24 ± 0.67 6 378.2 ± 34.1 207.7 ± 12.1 39.3 ± 1.9 165.8 ± 23.3 (8.18-8.51) (8.05-8.43) (10.06-11.68) (318^18) (191-228) (37^2) (140-190) 9.63 9.92 13.28 11 475.8 ± 21.1 249.4 ± 14.0 47.1 ± 2.2 274.1 ± 41.5 (9.51-9.74) (9.61-10.23 (12.13-14.42) (429-506) (228-271) (43-51) (200-320) 9.11 ± 0.15 9.37 ± 0.22 13.51 ± 0.67 10 453.7 ± 15.6 239.0 ± 16.0 44.8 ± 1.6 251.5 ± 35.0 (8.88-9.33) (9.07-9.68) (12.37-14.11) (436^86) (217-269) (43^8) (200-335) mm; at Site B2 between 10 and 15 May, three adult males had testes measuring 15 x 8, 14 x 9, and 14x8 mm, and one subadult male had testes measuring 6x4 mm. Three adult males taken between 26 April and 2 May at Site A2, Banggi Island, had testes measuring 15 x 7, 13 x 6, and 17x10 mm. External and cranial measurements of specimens from Banggi, Balambangan, and Molleangen (Table 11) fall within the range of specimens from mainland Borneo (Davis, 1962; Medway, 1977; Payne et al., 1985). However, ex- ternal and cranial measurements of specimens from Malawali Island (Table 1 1) are smaller than those from Banggi, Balambangan, and Molleangen, and from mainland Borneo. Chasen (1935) identified Banggi and Balambangan specimens as 5. m. otio- sus on the basis of a shorter tail length than the subspecies from mainland Borneo, S. m. bor- neanus. However, Musser and Newcomb (1983) further analyzed the same specimens examined by Chasen (1935) and concluded that these two sub- species are morphologically the same. Specimens examined— Total 146. Banggi: Site A 1 ( 1 9 FMNH, 3 UKMS), Site A2 ( 1 2 fmnh, 3 ukms). Balambangan: Site Bl (12 fmnh, 10 ukms). Site B2 ( 1 8 FMNH, 1 4 ukms). Malawali: Site C 1 (6 fmnh, 6 ukms). Site C2 (2 fmnh, 1 ukms). Molleangen: Site Dl (9 FMNH, 1 1 ukms). Site D2 (10 fmnh, 10 ukms). Order Carnivora Family Mustelidae Weasels and Otters Lutra perspicillata— This species is distributed throughout island and mainland Southeast Asia (Payne et al., 1985). On Banggi, otter tracks were seen on a beach at Wak-wak (Site Al) on 9 Feb- ruary. On 23 February I observed three individ- uals swimming in the open sea near the south- eastern part of Molleangen. Wells ( 1 977) collected Lutra perspicillata on Balambangan, and it is likely that the otters on Banggi and Molleangen belong to this species. The adult collected by Wells ( 1 977) was from a reed marsh. No specimens were examined. Family Viverridae— Civets Arctogalidia trivirgata— The small-toothed palm civet is an arboreal species known from islands offshore of Peninsular Malaysia and Singapore, but it has not been reported from offshore islands near Borneo (Medway, 1969; Payne et al., 1985). One adult female was caught on Banggi Island in a locally made live trap set in a tree in disturbed forest near a small stream, at about 2 m above the ground. External measurements (Table 12) fall within the size range of specimens from mainland MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 37 Table 12. Means (± SD) and ranges of selected measurements of adult Viverridae. Sample sizes are given separately for cranial and external measurements. Molar- Coady- Zygo- Mas- iform Palatal Fore- lobasal matic toid Orbital C tooth- breadth Palatal Total Tail arm Weight Island Sex N length width width length to M^ row at W length N length length length (g) Arctogalidia trivirgata Banggi f 1 92.83 54.67 35.85 38.57 35.04 13.70 25.25 49.60 1 1,011.0 557.0 84.0 1,550.0 Paradoxurus hermaphroditus Banggi m 1 93.74 54.32 33.19 38.04 33.86 13.87 23.13 47.80 - - _ _ _ Viverra tangalunga Banggi m 1 105.81 51.76 35.58 35.85 41.39 17.18 19.98 50.29 ----- Note: Measurements other than weight are in millimeters. Borneo; however, condylobasal length and zygo- matic length are slightly smaller (Davis, 1962; Pa>-neetal., 1985). Specimens examined— Banggi: Site A3 (1 fmnh). Paradoxurus hermaphroditus— Tht palm civet is a widespread species in Southeast Asia, reported on many islands offshore of Peninsular Malaysia, such as Tioman, Langkawi, Penang. and Singa- pore. The first report for the offshore islands of Borneo is an adult female I shot in selectively logged forest on 15 June at Site A3 on Banggi Island. According to local people, it is common in disturbed and primary forest throughout the island. Condylobasal length and zygomatic width (Table 1 2) fall within the range of a series of seven specimens from eastern Sabah (Davis, 1962). Specimens examined— Banggi: Site A3 (1 fmnh). llverra tangalunga— The Malay civet (or tan- galung) is a species inhabiting Peninsular Malay- sia. Borneo, Sumatra, and the Philippines (Payne etal.. 1985). r. /. ra/i^a/u/j^a is the only subspecies known on mainland Borneo, and it has also been reported on two adjacent islands. Karimata and Laut (Medway. 1965, 1977). On Banggi Island, a single adult male was shot by a hunter in logged forest at Site A3 on 1 April. This is the most com- mon civet on this island; I saw one individual in a logged area at Kalangkaman at about 7:30 p.m. on 29 .April, and several were reported by islanders in disturbed areas adjacent to primary forest at Site Al. Only cranial measurements are available (Table 12). Condylobasal length and zygomatic width of a single specimen are smaller than those of a series of seven specimens from eastern Sabah (Davis. 1962). Specimens examined— Banggi: Site A4 ( 1 fmnh). Order Artiodacty la Family Suidae— Pigs Si4s barbatus— The bearded pig is a common ungulate that occupies primary and secondary habitats in peninsular Malaysia, Palawan Island in the Philippines, and Borneo, including islands offshore of Sabah. On all four of these islands, I saw pig tracks near the shore and also far inland. Several were seen in a tapioca plantation at Site Bl on Balambangan Island. Because pig hunting is uncommon in this area, the pig population is high, and pigs are considered by the islanders to be a pest of cultivation. No specimens are available. Family Cervidae— Deer Ceni4s unicolor— The sambar deer is a wide- spread species in Asia, including larger islands such as Penang and Singapore, off the coast of Penin- sular Malaysia, and Laut, Balambangan, and Banggi, off the coast of Borneo. Chasen and Kloss (1931) obtained several pairs of antlers and skulls from Banggi Island, but not from Balambangan Island. Although deer himting was very active on Banggi and Balambangan islands during my study, the population is large on both islands. One major factor is habitat, especially the secondary habitat that was lef^ by several years of shifting cultiva- tion, providing a large volume of tender young twigs and grasses. A second factor may be the absence of competition for food with other brows- ing ungulates, and a third may be the absence of large carnivores. Hunting was concentrated at Sites 38 HELDIANA: ZOOLOGY Table 13. Means (± SD) and ranges of selected measurements of adult Tragulidae. Sample sizes are given separately for cranial and external measurements. Island Sex N Condylo- Zygo- basal matic Mastoid Rostral Orbital length width width length length Molari- Palatal form breadth toothrow at M^ Tragulus napu Banggi m 1 1 95.71 47.34 28.68 48.38 - 19.15 16.67 Balambangan f ; 1 87.10 43.33 20.14 42.34 31.47 17.23 15.41 — — — — — — — Note: Measurements other than weight are in millimeters. A2 and A3 on Banggi Island and at Sites Bl, B2, and B3 on Balambangan Island during my study. No specimens were examined. Family Tragulidae— Mouse Deer Tragulus napu — The greater mouse deer is a tiny ungulate species widespread in Southeast Asia, in- cluding small islands. Chasen and Kloss (1931) collected one adult male, one adult female, and one immature female from Banggi Island on 2 September 1 926 and described them as T. n. ban- guei. I saw one individual during a night survey at Site A2 in disturbed forest on Banggi Island. Two individuals were shot by hunters; one adult male was taken in selectively logged forest near Site B 1 on Balambangan Island and one subadult female in mixed grass and low tree vegetation near Site A3 on Banggi Island. Only skulls were given to me; cranial measurements (Table 1 3) of an adult male from Banggi Island are slightly smaller than those of an adult male collected by Chasen and Kloss ( 1 9 3 1 ) from the same island, and far smaller than a series from mainland Borneo (Chasen & Kloss, 1931; Davis, 1962). Specimens examined— Total 2. Banggi: Site Al (1 fmnh). Balambangan: Site Bl (1 fmnh). Results and Discussion Inventory of Mammals As far as can be determined, mammals on Bang- gi, Balambangan, and Malawali islands were first collected by a party from the Raffles Museum of Singapore (Chasen & Kloss, 1931). They spent 9 days (31 August to 8 September 1927) on Banggi Island, 2 days (8 and 9 September 1927) on Ma- lawali Island, and 5 days (9 to 14 September 1927) on Balambangan Island. Later, Wells (1977) spent only 1 day at Tanjung Periok on Balambangan Island, followed by Payne et al. (1985) on Bal- ambangan, Banggi, and Malawali islands. Based on published reports, I am unable to as- certain prior trapping effort and trapping methods. I believe that during the first visit by the Raffles Museum party, bats were sampled by shooting or caught by hand at roost sites, since mist nets were not available at that time. Thus, only a few bat species were reported from this visit, with many common species missed, including the abundant Cynopterus brachyotis and Rousettus amplexicau- datus. No serious attempt was made by Wells (1977) to investigate the bat fauna on Balamban- gan Island, from which he documented only two species, Cynopterus brachyotis and Kerivoula hardwickii. Payne et al. (1985) may have spent some time netting bats and possibly trapping bats with a harp trap on Banggi and Balambangan is- lands, from which they documented at least eight species of bats, but sites and times spent on these islands are not available to me. Among nonvolant mammals, previous collec- tors have recorded 1 6 species of small and large mammals on Banggi Island (one primate, one der- mopteran, three tree shrews, nine murid rodents, two ungulates), 1 1 species on Balambangan Island (one primate, one tree shrew, six murid rodents, three ungulates), and seven species on Malawali Island (one primate and six murid rodents). My recent survey increased by nine species the num- ber known on Banggi Island (two primates, one murid rodent, four civets, one ungulate, and one pholidotan, excluding a commensal species of rat, Rattus tanezumi); by four species the number known on Balambangan Island (one insectivore, one dermopteran, and two murid rodents); and by one species of ungulate the number known on Ma- lawali Island. The fauna of MoUeangen Island, un- known prior to this study, includes four sf)ecies MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 39 (two muhd rodents, one ungulate, and one pri- mate). Among bats, a few species were recorded by earlier collectors: only four on Banggi Island and eight on Balambangan Island, with none from Ma- lawali or Molleangen Island. Mist netting and trap- ping with a harp trap produced nine new records of bats on Banggi Island. 1 1 new species on Bal- ambangan Island, and six species each on Mala- wali and Molleangen islands. Collectively, only five species of fruit bats are now known on these four islands, compared to 1 6 species of insectiv- orous bats (one megadermatid. one nycterid. five rhinolophids, and nine vespertilionids). All 52 species of mammals known from these four islands are species mainly or exclusively found in the lowland and low hill areas on mainland Borneo. Out of a total of 25 bat species. 18 are known on Borneo only in the lowland areas below 9(X) m elevation, and the remaining seven are in both the low lands and in hill areas up to 1 800 m elevation (Pa>Tie et al.. 1 985). .All nonvolant mam- mal species known from these four islands have been reported on the mainland in both the low land and hill areas below 2000 m elevation, except the two species of large ungulates (Sus barbatus and Cervus unicolor) and one carnivore {Paradoxourus hermaphroditus). which are restricted to lowland areas, and Crocidurafuliginosa, which ranges from sea level up to 3700 m elevation on Mt. Kinabalu (Pa\Tie et al., 1985). Trapping, Netting, and Visual Surreys Small Mammals— Murid rodents were the most diverse group, representing about 24% of the spe- cies in eight mammalian families on Banggi Island. 38% of the species in sLx families on Balambangan Island, 62% of the species in four families on Ma- law ali Island, and 50% of the species in three fam- ilies on Molleangen Island (Table 14). Sundamys muelleri and Raitus tiomanicus were two murid species found on all four islands; the former was most common on Molleangen and Bal- ambangan and the latter species on Molleangen and Malawali. Three additional species, Staxomys whiteheadi. Siviventer cremohventer, and Maxo- mys surifer. were found on the three largest islands: the first two were common and abundant on Ma- lawali and Banggi islands. The last species was found at high density on Banggi and Balambangan islands, but it was rare on Malawali Island. The order Scandentia is represented by three species. Tupaia gracilis, Tupaia minor, and Tu- paia tana. All occur on Banggi Island, and one species, Tupaia minor, was found on Balamban- gan Island. The latter two species were ver\ com- mon in primar> and secondary forest, but the first species was confined to primar>' forest on the larg- est island. Of the six sciurids known from the four islands, all were found on Banggi Island, except one (Cal- losciurus notatus), which was found only on Ma- lawali Island. Only three species of this family were on Balambangan Island: Callosciurus pre- Yostii, Sundasciurus lowii, and Exilisciurus exilis. Some species of this family, Callosciurus notatus and Callosciurus prevostii, were strikingly abun- dant in disturbed forest and in plantations, where they feed largely on crop plants such as coconuts. Petaurista petaurista was often seen in selectively logged forest, and was seen to feed on figs on Bang- gi Island. Ratuffa affinis was very common in tall primary forest on Banggi Island, but it was very difficult to sample. Sundasciurus lowii was mod- erately common and was frequently caught and seen in secondary forest on both Banggi and Bal- ambangan islands. From the field trapping, I recorded 265 captures in 965 trap-nights on Banggi Island. 198 captures in 1.058 trap-nights on Balambangan Island. 229 captures in 940 trap-nights on Malawali Island, and 77 captures in 954 trap- nights on Molleangen Island (Table 1 ). The cumulative number of spe- cies captured reached an asymptote at 60 trap- nights on Molleangen Island and 142 traps-nights on Malaw ali Island (Fig. 1 0). On Banggi and Bal- ambangan islands there was no increase in the total number of species after 798 and 875 trap-nights, respectively (Fig. 10). Based on the cumulative number of species caught after about 1 ,000 trap- nights. I am convinced that my trapping effort on these islands was at least minimally adequate. It is parallel to the studies in the Philippines that indicate that 900 trap-nights are adequate to doc- ument species richness (Heaney et al.. 1989: Rick- art et al.. 1991). However, rare species such as Crocidurafuliginosa and Exilisciurus exilis can still be missed, especially on large islands. Crocidura fuliginosa was trapped only on Balambangan. but Exilisciurus exilis was not collected from any is- lands, although it was previously reported on Banggi Island. The percent of successful capture on all four islands varied from 8.4/ 1 00 trap-nights in primary forest on Molleangen Island to 3 1 .6 1 00 trai>-nights in secondary forest on Banggi Island. Trapping 40 HELDIANA: ZOOLOGY success in both primary and secondary habitats was highest on Banggi and Malawah islands: 24.6 and 25.6 in primary forest and 31.6 and 27.8 in disturbed forest, respectively. Trap success was moderately low on Balambangan Island (1 7.7 and 22.9 in primary and disturbed habitats) and lowest on MoUeangen Island (8.4 and 15.4 in primary and disturbed habitat) (Table 1). These results also show that the percent of successful capture on each island was higher in disturbed forest than in pri- mary forest; on Banggi, Balambangan, and Ma- lawali islands, success was slightly higher in sec- ondary forest but was double on MoUeangen Is- land. The same pattern was reported on Tioman Island near Peninsular Malaysia by Medway ( 1 966) and on Catanduanes Island in the Philippines (Heaney et al., 1991). Although the percent of suc- cessful capture was higher in disturbed forest, the species richness was higher in primary forest on two of the islands, Banggi and Malawali, and at the same number of species on Banggi and Mol- leangen (Table 1). Medway (1966) made a rough comparison be- tween trap success in primary forest on the main- land near Kuala Lumpur, Peninsular Malaysia and that in primary forest on Tioman Island, and he found Tioman Island to exhibit trap success five times higher than the mainland (5.0 and 28.6 per 100 trap-nights, respectively; Medway, 1966). Al- though no comparable data are available from the mainland of Sabah, results show the same pattern; trap success in this study was two to five times higher than trap success in primary forest near Kuala Lumpur reported by Medway (1966), two to eight times higher than in primary habitat be- tween 150 m and 1000 m on Kedah Peak (3.4- 6.6 per 100 trap-nights; Langham, 1975), and more than seven times higher than in mixed habitats at Pasoh, Peninsular Malaysia (1.2 per 100 trap- nights; Table 2; Kemper & Bell, 1985). Further, there is variation in percent of trapping success in primary forest on these islands com- pared to several other islands in the Philippines and Peninsular Malaysia; it is 4 to 12 times higher than on Leyte Island (1.8 to 4.4 per trap-nights; Heaney et al., 1989), 2 to 5 times higher than on Negros Island (4.5 to 13.7 per 100 trap-nights; Heaney et al., 1989), and 2 times higher than on Catanduanes Island (5.2 per 100 trap-nights; Hea- ney et al., 1991). However, trapping success in all habitats on Banggi (25.9 per 100 trap-nights), Bal- ambangan (19.00 per 100 trap-nights), Malawali (26.7 per 100 trap-nights), and MoUeangen (9.7 per 100 trap-nights) was slightly lower than on Tioman Island (36.2 per 100 trap-nights; Medway, 1966), near Peninsular Malaysia. There are two additional species of small mam- mals that were very difficult to sample or observe, and apparently low in density and very limited in distribution: Tarsius bancanus and Manis Javan- icus. Both species were seen only in old logged forest in the northeastern portion of Banggi Island. Three species of civets {Arctogalidia trivirgata, Paradoxurus hermaphroditus, and Viverra tan- galunga), one species of primate {Nycticebus cou- cang), and one species of dermopteran (Cynoce- phalus variegatus), although difficult to trap, were fairly common and well distributed in primary and disturbed forest on the largest island. Civets and N. coucang were found only on Banggi Island, but the dermopteran was found on Banggi and Bal- ambangan islands. Large Mammals— No large mammal trapping was done, and all specimens were obtained by shooting. Because there are not many large mam- mals on these islands, I have strong confidence that I have documented all large mammals. There are only three ungulate species, common and abundant in both primary and secondary forest on these islands: Cervus unicolor, Tragulus napu, and Sus barbatus. The first two species were found only on Banggi and Balambangan islands, but the latter occurs on all four islands. Fruit Bats— From this survey, five species of fruit bats were recorded on Banggi Island, four on MoUeangen Island, and three each on Malawali and Balambangan islands (Table 1 5). The number of fruit bats sampled from primary forest and dis- turbed forest was near the minimum acceptable sampling size, and it may be subject to sampling artifacts. Netting samples of about 100 individual fruit bats from each island were suggested to be likely to approximate both species richness and proportional abundance (Heideman & Heaney, 1989). Small pteropodids recorded in this survey in- clude Cynopterus brachyotis and Rousettus am- plexicaudatus. which were very common in pri- mary and secondary forest on all four islands, Eonycteris spelaea, which was found on Banggi and MoUeangen, and Macroglossus minimus, found on all islands except Balambangan. There is only one large pteropodid bat, Pteropus vam- pyrus, that was not sampled, but I or others have sighted it on Banggi and Balambangan islands. I netted 226 individuals of four species on Bang- gi Island (94 at Site Al and 132 at Site A2), 86 individuals of three species on Balambangan Is- MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 41 Table 14. List of mammal species found on Banggi, Balambangan. Malawali, and Molleangen islands. Taxon Banggi Balambangan Malawali Molleangen Order Insectivora— Insectivores Family Soricidae— Shrews Crocidura fuliginosa Order Scandentia— Tree shrews Family Tupaiidae— Tree shrews Tupaia minor Tupaia gracilis Tupaia tana Order Dermoptera— Colugo Family Cynocephalidae— Colugo Cynocephalus variegalus Order Chiroptera — Bats Family Pteropodidae— Fruit Bats Cynopierus brachyotis Eonycieris spelaea Macrogiosstds minimus Pteropus vampyrus Rousettus amplexicaudatus Family Megadermatidae— False Vampires Megaderma spasma Family Nycteridae— Hollow-faced Bats Nyvteris javanica Family Rhinolophidae— Horseshoe Bats Hipposideros cervinus Hipposideros diadema Hipposideros dyacorum Rhinolophus acuminatus Rhinolophus borneensis Rhinolophus trifoliatus Family Vespertilionidae— Common Bats Kerivoula hardwicki Kerixoula minuta Miniopterus australis Miniopterus magnater Miniopterus schreibersii Murina cyclotis Murina suilla Myotis macrotarsus Phoniscus atrox Pipistrellus javanicus Pipistrellus stenopterus Pipistrellus vordermanni Family Molossidae— Free-tailed Bats Cheiromeles torquatus Order Primates— Prosimians, Monkeys, Apes Family Lorisidae— Lx>ris Sycticebus coucang Family Tarsiidae— Tarsiers Tarsius bancanus Family Cercopithecidae— Monkeys Sfacaca fascicidaris *• +• (com.) 42 HELDIANA: ZOOLOGY Table 14. Continued. Taxon Banggi Balambangan Malawali Molleangen Order Pholidota— Pangolins Family Manidae— Pangolins Manis javanica Order Rodentia— Squirrels, Rats, and Mice Family Sciuridae— Squirrels Callosciurus prevostii Callosciurus notatus Exilisciurus exilis Petaurista petaurista Ratuffa affinis Sundasciunis lowii Family Muridae— Rats and Mice Maxomys surifer Maxomys whiteheadi Niviventer cremoriventer Rattus tanezumi diardii Rattus tiomanicus Sundamys muelleh Order Carnivora Family Mustelidae— Weasels and Otters Lutra perspicillata Family Viverridae— Civets Viverra tangalunga Paradoxurus hermaphroditus Arctogalidia trivirgata Order Arctiodactyla— Ungulate Family Suidae— Pigs Sus barbatus Family Cervidae— Deer and Mouse deer Cervus unicolor Tragulus napu +♦ - +• + -t-* +• + • +* +• +• ^ Documented during this survey. * Reported previously. » Sighted. ~ Not found. land (62 at Site Bl and 24 at Site B2), 205 indi- viduals of three species on Malawali Island (154 at Site CI and 50 at Site C2), and 155 individuals of four species on Molleangen Island ( 1 1 2 at Site Dl and 43 at Site D2). I caught no fruit bats in the harp trap. The total number of fruit bat species on these islands is similar to the total number of fruit bats known on Singapore Island (five species; Yang et al., 1990) and Tioman Island (three spe- cies; Medway, 1966, 1969), but it is much smaller than on small islands in the Philippines (Heaney, 1991a). The total netting success in primary and dis- turbed habitats was highest on Malawali and Banggi islands, with 5.30 and 4.62 bats per net-night, but it was lower on Molleangen and Balambangan is- lands, with 3.93 and 2.13 bats per net-night. Net- ting success in primary forest was lower than in disturbed forest, and it was highest in plantations. Two areas of primary forest with minimal distur- bance. Site B2 on Balambangan Island and Site D2 on Malawali Island, had netting success of 1 .44 (18 net-nights) and 1.73 (30 net-nights) bats per net-night, respectively, compared to a disturbed forest on Balambangan Island, with 3. 1 7 bats per net-night, and an old coconut plantation adjacent to disturbed forest at Site Dl on Malawali Island, with the high netting success of 22.67 bats per net- night (10 net-nights) (Table 2). My finding of higher netting success in planta- MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 43 BANGGI ISLAND MALAWALI ISLAND 9t r9- 6- 3 3 E ■+■ ■+■ ■+■ 300 600 900 Cumulative Trap Nights 1200 9 T 6 - I ■+■ -t- 300 600 900 Cumulative Tr^ Nights 1200 BAL.AMB.ANGAN ISLAND MOLLEANGEN ISLAND 9 T S- 6- ■+■ ■♦■ -H 9 T .Q. 6 <• ■+■ ■+■ ■+■ 300 600 900 Cumulative Trap Nights 1200 300 600 900 Cumulative Trap Nights 1200 Fig. 10. Cumulative numbers of species and trap-nights on Banggi, Balambangan, Malawali, and Molleangen islands 44 HELDIANA: ZOOLOGY Table 1 5. Physical characteristics and total number of mammals found on Banggi, Balambangan, Malawali, and Molleangen islands, North Borneo. Parameter measured Banggi Balambangan Malawali Molleangen Area (km^) 450 113 38 1.5 Elevation (m) 572 134 160 120 Distance from mainland (km) 12 21 9 11 Depth to large island (m) 35 35 18 14 Nonvolant species 24 14 8 4 Fruit bat species 5* 3* 3 4 Non-fruit bat species 9 10 3 2 * Plus prior record of P. vampyrus. tions than in primary forest is parallel to findings on Negros and Leyte islands (10.9 to 3.9 per net- night in plantation vs. 4.4 to 0.45 per net-night in primary forest; Heaney et al., 1989). Although my forest sites on Banggi and Balambangan islands were within the range of Negros, Leyte, and Ca- tanduanes islands (1.08 per net-night; Heaney, 1 99 1 a), my plantation site on Malawali Island had higher net success than agricultural areas on Ne- gros and Leyte islands in the Philippines. As sug- gested by Heaney et al. (1989), it may be that higher netting success in plantation/agricultural areas is due to the abundance of fruit sources. Insectivorous Bats— Because many insectiv- orous bats are generally difficult to catch with mist nets and not easily sampled with a harp trap (see Tuttle, 1974; Francis, 1989), I thus consider my data to be incomplete. I sampled only nine species on Banggi Island, ten on Balambangan Island, three on Malawali Island, and two on Molleangen Is- land. Relatively few insectivorous bats were caught in mist nets; two individuals of two species were netted in 44 net-nights on Molleangen Island, five individuals of two species in 44 net-nights on Ma- lawali Island, 33 individuals of six species in 45 net-nights on Balambangan Island, and 13 indi- viduals of five species in 47 net-nights on Banggi Island. Only insectivorous bats were caught in a harp trap. In six to eight trap-nights on each island, I caught one individual of one species on Malawali Island, five individuals of two species on Banggi Island, 23 1 individuals of seven species on Bal- ambangan Island, and none on Molleangen Island. Among these four islands, based on both trap- ping (harp trap) and netting, Balambangan Island had the highest number of insectivorous bat spe- cies, with ten species, but the lowest number of fruit bats, with three species (Table 1 5). The spe- cies taken in largest numbers in the harp trap was Miniopterus australis, in primary forest at Site B2 on Balambangan Island. This species was also taken in mist nets at Site A2 on Banggi Island. Another common species on Balambangan Island was Hip- posideros cervinus, which was also taken on Banggi Island. There were six insectivorous bat species that I found only on Balambangan Island; among these, Myotis macrotarsus was the most common species in primary forest, and Pipistrellus stenopterus was the most abundant species caught in mist nets set in disturbed forest at Site Al on Balambangan Island. The other four insectivorous bat species were uncommonly captured. There are six bat species represented each by one individual. Nycterisjavanica and Murina suil- la were taken only on Molleangen Island, Rhin- olophus trifoliatus and Pipistrellus javanicus were taken only on Malawali Island, and Pipistrellus vordermanni and Murina cyclotis were taken only on Banggi and Balambangan islands, respectively. Island Biogeography Geological History— The growth and reces- sion of continental glaciers during the Pleistocene caused global changes of sea level and temperature (Heaney, 1986). Sea level was 80 m or more lower than present levels at least four times during the Pleistocene (Oilier, 1975; Verstappen, 1975; Fair- banks, 1989). This fluctuation in sea level is as- sociated with climatic cycles and variation in the orbit of the earth around the sun (Pielou, 1 99 1 ; Muller & MacDonald, 1995). The greatest drop in sea level apparently oc- curred during the middle Pleistocene, about 1 60,000 years ago, when sea level reached 1 60 m below present levels (Gascoyne et al., 1970; Hea- ney, 1986). The Sunda Shelf islands were con- nected to each other and to the mainland. This MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 45 resulted in a land-bridge connection between the Palawan chain, which includes Balabac, Culion, Palawan, and Busuanga islands, and northern Bor- neo, because they are now separated by a channel 145 m deep. However, there was no continuous land bridge to the main body of Philippines due to several channels over 200 m deep (Dunn &. Dunn, 1977; Heaney, 1984, 1985, 1986, 1991b). Lack of topographical barriers between the Sunda Shelf and the Palawan chain allowed free migra- tion of various types of forest-dwelling species, including mammals; a large number of Asian mainland species invaded the western part of the Sunda Shelf and spread eastward as far as Borneo and the Palawan islands (Dunn & Dunn, 1977; Groves, 1985; Heaney, 1985, 1986). During the period 35,000-25,000 BP, major re- cession of continental glaciers resulted in flooding of the Sunda Shelf, and the sea level increased until it reached approximately the present level. During the last glaciation, between about 25,000 and 22,000 BP, the sea level dropped to about - 120 m and remained there for about 4,000 years (Dunn & Dunn, 1977; Fairbanks, 1989). At this time no land-bridge connection existed between the Pa- lawan chain and the Sunda Shelf, which were sep- arated by a channel, the Balabac Strait, between Banggi Island (close to Kudat Peninsula) and Bal- abac Island (close to the southern tip of Palawan Island) (Fig. 1 ). The distance between the two sides of the strait is estimated to have been about 1 0- 12 km (Dunn & Dunn, 1977; Heaney, 1986). Be- cause of this isolation, the Palawan chain seen today was a single large island during the late Pleis- tocene, but it has been isolated from its faunal source, Borneo, since the middle Pleistocene (Hea- ney, 1985, 1986). Balambangan, Banggi, Malawali, and Mollean- gen islands lie at the eastern edge of the continental shelf north of Borneo. These islands are separated from mainland Borneo by several narrow channels 10-35 m in depth. Based on the present depth of the sea (U.S. Defense Mapping Agency; scale 1:200,000) (see Geology and Climate section, above), I estimate that these four islands (Fig. 2) were separated from mainland Borneo about 9,000 years ago. This estimation is based on data from Dunn and Dunn (1977) and Fairbanks ( 1 989), who hypothesized that a rapid rise in sea level occurred beginning about 18,000 BP, from -120 m to a level within 10-15 m of present sea level by 6,000 BP. The current sea level was established at about 2,000 BP (Fairbanks, 1989, Fig. 2). Patterns of Distribution— The patterns of (nonvolant) mammalian distribution on these four islands and the adjacent islands on the Sunda Shelf and the Philippines can be studied by examining the present depth of the sea separating the islands and the previous history of increasing and de- creasing sea level during the Pleistocene (Heaney, 1984, 1985, 1986, 1991b; Groves, 1985). On the Sunda Shelf, species of mammals are widely dis- tributed from island to island, especially across Peninsular Malaysia, Sumatra, and Borneo, dem- onstrating dispersal of mammals across the shelf during the late Pleistocene. Because these four is- lands are part of the Sunda Shelf and have been separated only recently from mainland Borneo, it is not surprising that all of the nonvolant mam- mals recorded here are purely associated with Bor- neo (Table 14). Most endemic species on the Sunda Shelf are restricted to montane habitats (Heaney, 1985, 1986). Because the highest peak on Banggi Island is only 572 m, well below the lower limit of mon- tane forest at 900 m on Borneo (Davis & Payne, 1982; Kitayama, 1992), it is again not surprising that no endemic species are present on these four islands, and that the fauna is composed entirely of lowland species found on Borneo. Borneo, the largest and highest island on the Sunda Shelf (with its peak at 4 1 0 1 m on Mt. Kinabalu), has the high- est percentage of endemic species, 21%, compared to Sumatra with 5%, and Java with 1 2% (Heaney, 1986; Eari of Cranbrook, 1988). No endemic species were previously known on islands of the Sunda Shelf smaller than Java, a pattern supported by this study; evidence indicates that the faunas on smaller islands are relicts of the faunas on the nearest large islands (Medway, 1 966; Heaney, 1984, 1986). These islands probably shared the same fauna with modem Borneo when both were part of mainland Asia, but later declined in species richness due to the extinction process that took place after isolation from mainland Bor- neo about 8.000-1 0,000 years ago (Heaney, 1 986). Extinction rates are typically high on smaller islands and lower on larger islands; thus faunas on a smaller island will be less rich than on the larger one (MacArthur & Wilson, 1963, 1967; Heaney, 1984, 1985, 1986). On these four islands, the num- ber of nonvolant mammal species increases with island size; Molleangen Island, the smallest island in this group, has only 4 sp>ecies of nonvolant mammals, composed to Malawali, the second smallest island, with 8, Balambangan, the second largest island, with 14, and Banggi, the largest is- land, with 24 species. Further, nonvolant mammal 46 HELDIANA: ZOOLOGY species found on these islands also show the pat- tern of nested subsets: the fauna on a given island is a successive subset of the fauna from the next larger island (Patterson & Atmar, 1 986; Patterson, 1990; Patterson & Brown, 1991). These aspects of this study will be described in more detail else- where (Md. Nor & Heaney, in prep.). The nearest large islands to the north of Banggi, Balambangan, Malawali, and Molleangen islands are the islands in the Palawan chain. Despite the history of land-bridge connections during the mid- dle Pleistocene, about 160,000 years ago, the mammals of the Palawan chain are less similar to those of these islands than are those of Borneo. Only eight species of non volant mammals on the islands I studied (Tragulus napu, Manisjavanicus, Rattus tiomanicus, Sundamys muelleri, Macaca fascicularis, Paradoxurus hermaphroditus, Viverra tangalunga, and Sus barbatus) are represented on the islands of the Palawan chain, other than introduced commensal species (Heaney, 1 986, Ta- ble 1; see also Table 14, this paper). However, endemism is high; Palawan Island has the largest number of endemic mammal species of any of the islands that were connected to the mainland dur- ing the middle Pleistocene (Groves, 1985). Nearly two-thirds of the mammals found on Palawan oc- cur nowhere else (Groves, 1985; Heaney, 1986). Clearly, the character of the fauna of these four islands was determined overwhelmingly by the es- tablishment of a land bridge to Borneo ca. 15,000 years ago, with scarcely a trace of the earlier con- nection to the islands to the north. Conclusion In the future, the large range of habitats on the two largest islands, Banggi and Balambangan, should be further investigated to ensure adequate mammal sampling. This includes all habitats that were not surveyed owing to time and logistical constraints during my study, especially primary habitat above 350 m on Banggi Peak, and selec- tively logged forest and primary lowland forest in the central portions of Banggi and Balambangan islands. Although morphological variation in these is- land populations has been investigated by several researchers in the past, more thorough and com- plete analysis is needed, especially on the newly reported species such as insectivorous bats, civets, and primates. The results presented above lead to several con- clusions and suggestions associated with the sys- tematics, general ecology, and evolution of mam- mals on these islands. First, the number of mammal species found on these four islands was much less than in any com- parable habitat on the mainland of Borneo. For example, the total number of nonvolant mammal species found on Malawali Island (Tables 4 and 5; eight species in 38 km^) was far less than that in similar habitat, the lowland forest of Sepilok For- est Reserve (Payne, 1989; 53 species in 44 km^). The total number of species found on Malawali Island represented only about 1 8% of the species found in lowland forest on mainland Borneo. Nev- ertheless, each small mammal fauna showed con- siderable diversity, especially with the new records of primates and civets on Banggi Island (Table 4). However, the large mammal taxa are generally depauperate, with only three medium- and large- size ungulates and no large carnivores. Second, the diversity and composition of the nonvolant mammal fauna on these four islands are directly related to island size. The species on smaller islands are a subset of the next larger fauna, which is in turn a subset of the next larger fauna. These patterns support the conclusion that these are land-bridge islands that were connected both to each other and to mainland Borneo during the late Pleistocene. The rise of sea level that began about 1 8,000 years ago isolated these four islands from the mainland. Selective extinction appears to have predominated subsequently, and it has shaped the faunas on these islands, with species richness on each island determined by island size. Third, the mammalian fauna on these islands is composed entirely of species found in lowland forest on Borneo. Among the four islands, Banggi is the largest and has the highest elevation, at 572 m (Banggi Peak), but it is below 900 m, the lower limit of montane forest in Borneo (Davis & Payne, 1982). Fourth, although no endemic species are present on these islands, there are two Bomean endemic species found on Banggi Island: Tupaia gracilis and Exilisciurus exilis. This is less than 7% of the total 29 endemic species known from Borneo (Medway, 1965, 1977; Payne et al., 1985). The absence of montane and higher elevation habitats probably was the main factor restricting the pres- ence of endemic species, because most of the en- demic species on Borneo are montane species (Payne etal., 1985; Heaney, 1986). This resuh also supports the observation of Heaney (1986) that MD. NOR: MAMMALIAN FAUNA ON ISLANDS NORTH OF BORNEO 47 no endemic species occur on Sunda Shelf islands smaller than Java (125,628 km^). Fifth, there was only one commensal species associated with plantations and human settle- ments: two individuals of Rattus tanezumi were sampled at Site A2 on Banggi Island, but no other commensal species such as Rattus exulans was found. An increase in commensal species is nor- mally associated with destruction of natural hab- itats through logging and clearing for agriculture and human settlements. In the early 1920s, Merrill (1926) estimated that about 58% of Banggi Island was covered by primary forest. Although logging activity was started as early as the 1960s, I found that areas of primary forest covered about 25% of Balambangan and 30% of Banggi Island, including forest that has been selectively logged. Increased human population may soon reduce the size of natural forest; however, thus far the population on these islands has not exceeded 5,000 people at any time. Presently there are fewer than 5,000 on Banggi Island, fewer than 500 on Balambangan Island, fewer than 300 on Malawali, and fewer than 100 on MoUeangen Island. Acknowledgments I thank Dr. Lawrence Heaney for his construc- tive comments throughout the preparation of this manuscript. I am indebted to many people, in- cluding Dr. Joel Brown, Dr. Thomas Poulson, the staff at the Field Museum of Natural History, Ms. Lucy Kimsui and Mr. Awang Latiff, the staff at the Zoological Museum at Universiti Kebangsaan Malaysia, Kota Kinablau, the staff at District Of- fice of Banggi Island, the staff at the Research Col- lection, Zoology Department, National University of Singapore, the Police and Field Force at Ka- rakit, and the biology students at Universiti Ke- bangsaan Malaysia, Kota Kinabalu, Sabah. Fi- nally, I thank Associate Professor Robert Butler Stuebing, Curator, Museum of Zoology, Universiti Kebangsaan Malaysia, Kota Kinabalu, who gave much advice and help when I was in the field; Mr. Mahedi Andau, the Director of Sabah Wildlife Department, who allowed me to use harp traps and facilities belonging to the department; and Mr. Johar Solehen, who help)ed to sample several sp)e- cies of ungulates, civets, and tree squirrels. 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