Mammalia 2016; 80(6): 579–592

Eric A. Rickart*, Danilo S. Balete, Phillip A. Alviola, Maria J. Veluz and Lawrence R. Heaney The of Mt. Amuyao: a richly endemic fauna in the Central Cordillera of northern Luzon Island,

DOI 10.1515/mammalia-2015-0132 Received August 3, 2015; accepted November 10, 2015; previously Introduction published online January 20, 2016 Oceanic islands are well known for their richly endemic Abstract: Faunas of old oceanic islands often have biotas, but mammals on such islands have been surpris- extremely high levels of and are considered ingly poorly documented. At 103,000 km2 (United Nations highly susceptible to anthropogenic disruption. We sur- Environmental Programme 2010), Luzon, in the northern veyed the richly endemic small fauna on Mt. Philippine archipelago, is the largest island that is entirely Amuyao in the Central Cordillera of northern Luzon oceanic. Recent studies on Luzon have documented at Island, Philippines. We tested hypotheses regarding least 47 native non-flying mammals, of which 42 (89%) are elevational patterns of richness and community endemic (Heaney et al. 2013a, 2014a,b, 2016, Balete et al. composition, community response to habitat disturbance, 2015), and it seems certain that other endemic species are and interactions of native and non-native mammals. Our yet to be discovered in poorly explored areas. study revealed greater species richness and faunal hetero- Luzon has a long and complex geological history (Hall geneity within the Central Cordillera than previously sus- 2012) which is closely associated with faunal diversifica- pected. We documented 15 native species (14 and tion, much of which resulted from autochthonous spe- 1 insectivore), and two species of non-native rodents. All ciation (Jansa et al. 2006, Heaney et al. 2011, 2013b, 2016, of the native species are endemic to the Philippines, eight Justiniano et al. 2014). Although progress has been made being restricted to the Cordillera. Twelve of the 14 native in documenting the mammal faunas in many portions of rodents belong to two ancient endemic , indicating Luzon, little has been published on mammals of the largest that most of the regional diversity is the product of in situ and most species-rich area, the Central Cordillera, and this speciation. Native mammal assemblages are ecologically has limited our perspective on the evolution, ecology, and diverse, and include species with varied trophic habits, conservation of this richly endemic fauna. activity patterns, and climbing ability. Some native species The Cordilleran mammal fauna was introduced are restricted to relatively pristine habitat, whereas others to science in the late 19th century through specimens are highly tolerant of disturbance. Non-native species are obtained from Mt. Data (2310 m) and elsewhere by British restricted to highly disturbed habitats and apparently are naturalist John Whitehead (Figure 1, Thomas 1898). displaced by natives where habitat has regenerated from During the 20th century, Mt. Data remained the principal past disturbance. focus of collecting efforts on Luzon (Sanborn 1952, Rabor 1955). Our 2000–2003 study in Balbalasang-Balbalan Keywords: biogeography; conservation; elevational National Park (Rickart et al. 2011b) was the first com- ­gradients; endemism; species richness. prehensive survey of mammals in the Cordillera region, involving standardized sampling along a local elevational habitat gradient to facilitate quantitative comparisons *Corresponding author: Eric A. Rickart, Natural History Museum of with gradient surveys conducted in other regions of the Utah, 301 Wakara Way, University of Utah, Salt Lake City, UT 84108, Philippines (Heaney et al. 1989, 2006, Rickart et al. 1991). USA, e-mail: [email protected] However, that study was conducted on Mt. Bali-it, a peak Danilo S. Balete and Lawrence R. Heaney: Field Museum of Natural that reached only 2238 m, well short of the maximum ele- History, 1400 S Lake Shore Drive, Chicago, IL 60605, USA vation in the Cordillera (2930 m). Phillip A. Alviola: Museum of Natural History, University of the Philippines at Los Baños, College, Laguna 4031, Philippines Here, we report results of surveys undertaken in 2007 Maria J. Veluz: National Museum of the Philippines, Rizal Park, and 2011 on Mt. Amuyao (2702 m), the fourth highest Manila, Philippines mountain on Luzon. To determine the nature and extent of 580 E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines

both of which are located within the same contiguous area of highland habitat above 1500 m (Figure 1). The Central Cordillera, extending nearly 300 km from the northern tip of Luzon south to the Central Valley, is an uplifted mag- matic arc associated with subduction in both the East Luzon Trench and the Manila Trench. The core of the Cordillera consists of Eocene–Oligocene plutonic rocks with associated marine sedimentary rocks. Uplift and vol- canic activity occurred during the Late Oligocene–Middle Miocene (33–12 Ma) in conjunction with westward subduc- tion of the Philippine Sea Plate along the Manila Trench, followed by Pliocene–Quaternary (5–0 Ma) uplift and extensive magmatism (Ringenbach et al. 1990, Hall 2002, 2012, Hollings et al. 2011). Much of the Cordillera west of Mt. Amuyao has exposed extrusive and intrusive igneous Figure 1: Map of northern Luzon Island showing areas of highland rocks (andesite and granite), whereas to the east under- habitat and location of Mt. Amuyao in relation to other peaks in the lying sedimentary rocks include sandy shale and sand- Central Cordillera. stone, of which the latter predominates on the surface of Mt. Amuyao (Smith 1915: 192). possible faunal variation within the Central Cordillera, we We surveyed mammals from 17 February to 26 March sought to survey a new site geographically distinct from 2007 and from 5 to 27 April 2011 at 15 localities along an Balbalasang. We were particularly interested in access- elevational gradient on the northern aspect of Mt. Amuyao ing areas at elevations higher than those available at Bal- from the nearby town of Barlig (ca. 1500 m) to the moun- balasang. In order to gain greater insight into the effects tain summit (2702 m). These localities encompassed the of anthropogenic disturbance on native and non-native range of natural forest habitats and included areas with mammals, we surveyed habitats ranging from agricultural varied levels of natural and anthropogenic disturbance lands and early second growth to relatively undisturbed from agricultural land to nearly pristine forest (Figure 2). mature forest. Detailed information on the of Mt. Amuyao, includ- Some of the data from the Mt. Amuyao survey have ing an assessment of diversity across elevation, can appeared in previous publications describing newly dis- be found elsewhere (Salcedo 2001). The following descrip- covered taxa (Balete et al. 2012, Heaney et al. 2014a), new tions of our survey localities are based on our field notes. distributional records of bats (Heaney et al. 2012), and the Where our localities and those of Salcedo (2001) coin- impact of habitat disturbance on small mammals (Rickart cided, we list the dominant plants from her study. et al. 2011a). Here, we present the comprehensive results –– Locality 1. 1.0 km S, 0.6 km E Barlig Municipal Hall, from our elevational transect survey of the non-flying 1510 m elev., 17.04030°N, 121.10583°E. 21–22 February small mammals, placing them within the broader context 2007. At this locality southeast of Barlig we trapped of our earlier gradient studies. Much of the data presented in early second-growth habitat on abandoned rice ter- here constitutes the first information on several species races overgrown with saplings, ferns (Cyathea), endemic to the Central Cordillera. shrubs, and cane grass (Saccharum). –– Locality 2. 1.1 km S, 0.6 km E Barlig Municipal Hall, 1530 m elev., 17.03797°N, 121.10424°E. 18–20 February 2007. At this locality we trapped in areas of active agri- Materials and methods culture that included terraced vegetable gardens and along grassy margins of rice fields (Figure 2A). Study area –– Locality 3. 0.5 km S, 0.2 km E Barlig Municipal Hall, 1535 m elev., 17.04109°N, 121.10291°E. 18–20 February Mt. Amuyao is located in the east-central portion of the 2007. This locality was on a steep slope with grasses, Central Cordillera, approximately 60 km south of Mt. shrubs, scattered (Pinus kesiya), cultivated Bali-it from which is it separated by intervening land banana (Musa), and sweet potato (Ipomoea). below 1500 m elevation, and approximately 30 km north- –– Locality 4. 2.15 km N, 1.25 km W Mt. Amuyao summit, east of Mt Data and 50 km north of Mt. Pulag (2922 m), 1650 m elev., 17.03270°N, 121.11604°E. 19–27 April 2011. E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines 581

A B 2007. Habitat at this locality was secondary forest with undergrowth of cane grass, forbs, and bracken fern (Pteridium). Undergrowth was periodically burned to promote herbaceous vegetation for live- stock forage. –– Locality 6. 0.3 km N Barlig Municipal Hall, 1760 m elev., 17.04694°N, 121.09801°E. 18–23 February 2007. This locality (Figure 2B) was along a ridge in open pine forest with between 12 and 20 meters in height, the largest of which had dbh of ca. 60 cm. The under- story, which was regularly burned, included cane grass and bracken fern with scattered shrubs (Rubus, C D Melastoma, and Vaccinium). Ground cover included pine needles and dead grass over moderately rocky volcanic soil. –– Locality 7. 0.6 km N Barlig Municipal Hall, 1800 m elev., 17.04820°N, 121.09977°E. 21–25 February 2007. This locality was in remnant montane forest near sec- ondary pine forest (locality 6). Height of the forest can- opy was 10–15 m, and emergent trees reaching 20 m. Canopy and emergent trees had dbh of 30–60 cm. Dominant trees included oaks and figs that supported epiphytic mosses, ferns, and orchids. In addition to figs, fruiting plants included vines (Piper) and small

Figure 2: Habitats represented along the Mt. Amuyao survey gradi- trees and shrubs (Melastoma, Helicia, and Vaccin- ent. (A) Rice terraces near Barlig, ca. 1550 m elevation, illustrating ium). Other understory plants included herbaceous the disturbed agricultural and early second growth habitats at ferns, tree ferns, and palms. Ground cover included localities 1–3. (B) Secondary pine (Pinus keysia) forest and under- moss, ferns, small palms, and cane grass. There was a story grasses at locality 6, ca. 1760 m elevation. (C) Lower montane thin cover of litter over a 3–10 cm layer of humus. forest near locality 4, ca. 1650 m elevation. (D) Mossy forest near –– Locality 8. 1.75 km N, 0.4 km W Mt. Amuyao summit,­ locality 14, ca. 2550 m elevation. 1885 m elev., 17.02929°N, 121.12466°E. 23–26 March 2007. This locality was situated on the northern This locality was in lightly disturbed lower montane aspect of Mt. Amuyao, on steep terrain in mature forest southeast of Barlig (Figure 2C). The terrain was montane forest. Dominant woody plants noted by relatively steep (ca. 40° average slope). Height of for- Salcedo (2001) near this locality and locality 11 est canopy was 15–20 m, with emergent trees 25–30 m. included Decaspermum fruticosum (Myrtaceae), Canopy and emergent trees had diameters at breast Horsfieldia megacarpa (Myristicaceae), Lithocarpus height (dbh) of 20–60 cm. Dominant trees included jordanae and L. solerianus (Fagaceae), Phyllocladus oaks (Lithocarpus), myrtles (Syzygium), and laurels in hypophyllus (Podocarpaceae), Piper sp. (Piperaceae), areas with deep soils, with pines and figs (Ficus) pre- Schefflera sp. (Araliaceae), and Vernonia bengueten- dominant in rocky areas. Canopy ephiphytes included sis (Asteraceae). mosses, ferns, and orchids. Canopy vines included –– Locality 9. 1.75 km N, 1.5 km W Mt. Amuyao summit, Schefflera and Tetrastigma. Understory plants 1950 m elev., 17.02595°N, 121.11301°E. 24–26 March included tree ferns, palms (Pinanga), wild banana 2007. This locality was on a steep slope in mature mon- (Musa) and various flowering trees and shrubs (Astro- tane forest. Dominant trees included oaks, ­laurels, nia, Calophyllum, Ficus, Helicia, Psychotria). Ground and myrtles up to 20 m high with dbh of 25–50 cm, cover plants included ferns, orchids, taro (Alocasia) with ephiphytic mosses, ferns, and orchids. and gingers (Zingiber). There was 3–5 cm of leaf litter –– Locality 10. 1.25 km N, 0.5 km W Mt. Amuyao summit, over a humus layer of 5–7 cm. 1990 m elev., 17.02602°N, 121.12276°E. 22 March 2007. –– Locality 5. 0.2 km N, 0.3 km E Barlig Municipal Hall, This locality was on steep terrain in mature montane 1675 m elev., 17.04444°N, 121.10260°E. 21–22 February forest. 582 E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines

–– Locality 11. 1.0 km N, 1.0 km W Mt. Amuyao summit, herbaceous ferns, a dwarf, grass-like bamboo, tree 2100 m elev., 17.02213°N, 121.11791°E. 16–26 March ferns, Melastoma, Rhododendron, Vaccinium, and 2007; 5–10 April 2011. 3040 trap-nights. This locality laurels. Leaf litter was 4–10 cm thick and continuous was in mature montane forest along a ridge northwest over humus 10–100 cm deep. Between 26 February of Mt. Amuyao summit. Average slope was ca. 25°, and 12 March, mean daily maximum temperature ranging between 10° and 60°. The forest canopy was was 14.6°C (13.5–16°) and mean daily minimum was at 15–20 m with about 80% cover. Emergent trees were 9.2°C (7.5–11°). 25–30 m in height. Dominant trees included oaks, –– Locality 15. Mt. Amuyao summit, 2690 m elev., laurels, myrtles, and eleaocarps, with some scat- 17.01330°N, 121.12807°E. 2–11 March 2007. Habitat at tered pines along ridgelines. Abundant canopy epi- the summit of Mt. Amuyao was dwarfed mossy forest. phytes included mosses, ferns, orchids, and pitcher Height of woody vegetation on the summit was 2 m or plants (Nepenthes). Vines included climbing bam- less and up to 5 m on slopes immediately below the boo (Schizostachyum), pandans (Freycinetia), Piper, summit. Vegetation was dense and continuous except Tetrastigma, and other woody species. Understory for disturbed areas along trails and in clearings. Dom- plants included tree ferns, saplings, and shrubs, with inant plants forming the “canopy” included myrtles, a ground cover of ferns, herbaceous plants, and club laurels, oaks, and Rhododendron, with understory mosses. Grass was present under pines. Leaf litter was vegetation including ginger, ferns, orchids, and dwarf 3–10 cm thick and continuous over a layer of humus bamboo. Moss covered the ground and most under- 10–30 cm thick. Moss-covered logs were abundant. story surfaces. Small fallen branches were common, Disturbance included numerous trails and pit-traps and there was sparse leaf litter over a thin ( < 5 cm) for wild pigs. layer of humus covering rocky soil. Dominant woody –– Locality 12. 0.75 km W Mt. Amuyao summit, 2300 m plants listed by Salcedo (2001) included Lithocarpus elev., 17.01467°N, 121.12196°E. 9–14 March 2007. This jordanae and Lithocarpus luzoniensis (Fagaceae), locality was in a ravine with a shallow stream. Habi- Eurya spp. (Theaceae), Schefflera simplicifolia (Arali- tat was mossy forest with oaks, myrtles, laurels, and aceae), Rhododendron subsessile (Ericaceae), Tas- podocarps 15 m or less in height and dbh of ­20–40 cm. mania piperita (Winteraceae), Rubus pectinellus The terrain was steep and rocky with shallow soil (Rosaceae), Discocalyx montana (Myrsinaceae), and and humus. Dominant woody plants recorded by Melastoma sp. (Melastomataceae). Salcedo (2001) near this locality included Cyrtandra sp. (Gesneriaceae), Dacrycarpus steupii (Podocar- paceae), Diplycosia luzonica (Ericaceae), Eurya nitida Survey procedures (Theaceae), Perrottetia alpestris (Celastraceae), Psy- chotria sp. (Rubiaceae), Rubus pectinellus (Rosaceae), Surveys involved trapping of small ( < 500 g body mass) Vernonia benguetensis (Asteraceae), and Viburnum mammals including (Soricidae) and rodents luzonicum (Caprifoliaceae). (). Methods followed those used in previous –– Locality 13. 0.4 km N, 0.4 km W Mt. Amuyao summit, surveys conducted elsewhere on Luzon (Heaney et al. 2480 m elev., 17.01727°N, 121.12393°E. 27 February–13 1999, 2013a,c, Rickart et al. 1991, 2011b, 2013, Balete March 2007. This locality was in a moist ravine within et al. 2009, 2011, 2013a,b, Alviola et al. 2011, Duya et al. mossy forest similar to that at locality 12. 2011). Survey effort was expressed as trap-nights (i.e. 1 –– Locality 14. 0.5 km N, 0.5 km W Mt. Amuyao summit, trap set for 24 h). Nearly two-thirds of the total trapping 2530 m elev., 17.01717°N, 121.12188°E. 27 February–14 effort consisted of ground trapping, principally under March 2007; 12–17 April 2011. This locality was in root tangles, at burrow entrances, along runways, and mossy forest along a ridge northwest of Mt Amuyao beside or on top of fallen logs. At localities in mature summit (Figure 2D). Slope varied from nearly level forest, some traps were set 1–5 m above the ground on the ridge top to ca. 80° on the sides of the ridge. surface on inclined tree trunks, horizontal branches, Tree canopy varied from 5 m along the ridge top to within tree cavities, and at intersecting vines (hereaf- 20 m on the sides, and was discontinuous due to tree ter, “arboreal trapping”). Traps were baited either with falls and landslides. Dominant trees included podo- pieces of sliced coconut lightly fried in cooking oil and carps, myrtles, laurels, and oaks, with dbh of 50– coated with peanut butter (“coconut bait”), or with live 80 cm. Epiphytic mosses, ferns, and orchids were annelid earthworms obtained locally. Earthworm-baited abundant. Understory plants included saplings, traps were set exclusively on the ground and constituted E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines 583 nearly one-third of the total trapping effort. Although Results our trapping methods did not target larger species ( > 500 g), we gathered information on their occurrence Small mammals from local residents and obtained a few specimens from hunters. Voucher specimens for all documented species Trapping at 15 localities for a total of 13,019 trap-nights, were deposited at the Field Museum of Natural History, we captured 665 small mammals representing 15 species of which half will be returned to the National Museum of including 1 native , 12 native murid rodents, and two the Philippines. non-native murid rodents (Table 1). Three of the native rodents ( maximus Balete et al., 2012, Musse- Data analysis romys inopinatus Heaney et al., 2014a, and mon- tanus Balete et al., 2012) were newly discovered during our In assessing the distribution of native species across surveys of Mt. Amuyao. Subsequently, we discovered that the elevational gradient, we used the “range-through” S. montanus also occurs on Mt. Data and Mt. Pulag (Rickart assumption of occurrence (Rowe 2009), where the number et al. 2011a); at present, the other two species are known of species considered present at a given sampling locality only from Mt. Amuyao. The remaining native species are included those directly recorded plus those assumed to ­Philippine endemics with geographic distributions ranging be present because of their occurrence at both lower and from the greater Cordillera region to the oceanic Philip- higher elevations. Secondary localities with limited sam- pines, and the two non-native species occur throughout the pling were excluded from our assessment of elevational Philippines and beyond (Table 1, Heaney et al. 2010). patterns. However, data from secondary localities were At three of the nine principal localities (2100 m, 2530 included in assessments of overall capture frequencies of m, and 2690 m) the number of native species trapped species based on bait type, diel period, and trap position. reached terminal plateaus that extended for more than To measure the adequacy of sampling, we plotted species 500 trap-nights of sampling. However, at 2530 m we accumulation curves for each of the principal sampling inferred the presence of two additional native species that localities as well as a cumulative curve for all localities were documented at higher and lower elevations (Table 1). combined, beginning with the lowest elevation locality At the other principal trapping localities, species accumu- and proceeding upward. lation curves did not achieve plateaus. The curve for the Relative abundance of species was measured through combined localities (Figure 3) shows a rapid increase to 11 trapping success expressed as capture rate (i.e. the number species after fewer than 2000 cumulative trap nights with of captures per 100 trap-nights). The number of relevant the sequential addition of localities up to 1650 m. Two trap-nights varied for different species based on their more species were added after 4500 trap nights follow- climbing habits (i.e. strictly ground-dwelling, scansorial, ing the addition of localities in montane forest between or strictly arboreal) and body size (i.e. < 100 g vs. > 100 g), 1800 and 2000 m. An additional 8000 trap-nights at the because these characteristics determined likelihood of five localities above 2100 m in upper montane and mossy capture in traps set above ground and in traps of different forest did not add any new species. sizes. Most native species were broadly distributed across the We used χ2-tests to assess patterns of bait attractive- survey gradient (Table 1; Figure 4), and all but one (Musse- ness, ground vs. arboreal capture frequencies, and diel romys inopinatus) were captured ten or more times. Seven activity where total samples included 20 or more individ- of the 13 native species [Crocidura grayi Dobson, 1890, uals and there were at least five individuals per category. datae (Meyer, 1899), Apomys musculus Miller, 1911, For smaller samples we used a binomial test. Expected Archboldomys maximus, Bullimus luzonicus Thomas, 1895, frequencies for bait type and trap position were based silaceus (Thomas, 1895), and Chrotomys white- on the number of trap-nights at localities where species headi Thomas, 1895] were trapped or inferred to occur at all were either documented or inferred to occur. For diel of the principal localities in forest habitat from 1650 m to activity, expected frequencies for diurnal and nocturnal/ the summit of Mt. Amuyao (2690 m). Documented ranges crepuscular captures were 0.42 and 0.58 representing of three other species ( granti Thomas, 1895, the approximate length of the two periods (10 h and 14 everetti GÜnther, 1897, and ­Soricomys montanus) were h, respectively). The relationship of capture parameters nearly as broad, and even Musseromys inopinatus, with with elevation was assessed using Spearman’s rank cor- only five captures, was recorded at four localities between relation (rs). 1650 and 2300 m elevation. Rhynchomys soricoides was not 584 E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines 2 5 13 42 57 51 21 32 46 15 14 26 13 10 16 23 294 665 Total 13,019

0 9 0 0 0 1 3 1 0 0 0 4 1 1 3 62 17 93 1130 2690

c c 0 0 0 0 4 2 3 0 1 6 1 3 0 0 45 15 80 2470 2530 9 ( + 2)

c c c 0 0 8 0 0 1 3 0 1 1 1 0 0 0 19 47 13 625 Locality elevation (m) elevation Locality 2480 8 ( + 3)

c c c c 0 0 2 0 0 1 3 2 1 1 0 0 0 0 32 52 10 1222 2300 8 ( + 4)

0 0 6 4 3 0 0 2 7 3 3 1 3 72 12 12 13 129 3040 2100

0 4 4 0 1 0 0 7 0 0 0 0 1 0 1 0 0 0 129 1990

0 5 5 0 0 0 0 9 0 0 1 0 0 0 0 1 1 1 106 1950

c c c 0 0 0 5 2 0 0 0 2 2 4 1 0 0 0 24 40 569 1885 7 ( + 3)

c c c c c c 1 3 0 1 4 2 1 1 0 0 0 0 0 0 0 21 33 457 1800 6 ( + 6)

0 2 0 4 5 0 1 0 1 0 2 0 0 0 0 2 44 33 472 1760

0 2 0 1 0 0 0 0 4 0 0 0 0 0 0 6 3 13 157 1675

0 0 4 1 1 2 6 5 0 3 2 0 0 12 28 11 16 80 2270 1650

0 2 0 3 0 0 0 0 2 0 4 1 0 0 0 8 7 22 247 1535

0 2 0 0 0 0 0 0 0 0 0 0 0 7 0 0 1 6 75 1530

0 2 0 1 0 0 0 0 4 0 0 0 0 9 0 0 2 3 50 1510

SD (n) ± SD X Adult mass 21.2 ± 1.8 (8) 9.9 ± 0.5 (30) 24.7 ± 2.7 (7) 17.3 ± 2.0 (3) 77.2 ± 6.5 (30) 62.1 ± 6.1 (15) 42.4 ± 6.0 (13) 66.8 ± 6.6 (20) 159.9 ± 17.4 (8) 178.2 ± 11.5 (5) 311.0 ± 35.1 (9) 463.8 ± 28.7 (4) 183.5 ± 14.5 (8) 126.8 ± 22.2 (14) 131.8 ± 17.8 (17)

a P C C C P C C L P L C C Distribution C W W

b b Non-native species. Non-native C, Endemic to Central Cordillera; L, endemic to Luzon faunal region; P, endemic to oceanic Philippines; W, widespread beyond the Philippines. beyond widespread W, Philippines; oceanic to endemic P, region; faunal Luzon to L, endemic Cordillera; Central to C, Endemic Presence inferred from occurrence at both higher and lower elevations (principal localities only). localities (principal elevations lower both higher and at occurrence from inferred Presence Principal localities in mature forest are shown in italic. shown are forest in mature localities Principal Apomys musculus Apomys No. non-native species non-native No. Apomys datae Apomys No. native species ( + inferred) species native No. Apomys abrae Apomys Total trap nights trap Total Rattus tanezumi Rattus Rhynchomys soricoides Rhynchomys Crocidura grayi Crocidura Archboldomys maximus Archboldomys whiteheadi Chrotomys Batomys granti Batomys Rattus everetti Rattus Bullimus luzonicus Bullimus exulans Rattus montanus Soricomys Total captures Total Chrotomys silaceus Chrotomys inopinatus Musseromys Distribution of small mammal species along the elevational gradient of Mt. Amuyao. Mt. Amuyao. of gradient the elevational along species mammal small of 1: Distribution Table Species a b c E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines 585

14 1990 m 1 to 13 (Table 1). At the eight principal sampling localities 12 1800 m in relatively undisturbed mature forest (1650 m to 2690 m), 2100 m 2300 m 2530 m 2690 m 1885 m 1950 m 2480 m species richness ranged between nine and 13 and was not 10 1760 m correlated with elevation (rs = -0.217; p > 0.2). 1675 m 8 Habitat disturbance had a major impact on the occur- rence patterns of individual species. The two non-native 6 species (Rattus exulans and Rattus tanezumi) were common

Number of species or abundant below 1600 m at localities with the most dis- 4 1650 m 1535 m turbed habitat (cropland and early second growth), and 2 1530 m also at two localities in secondary pine forest (1675 and 1510 m 1760 m) where undergrowth was periodically burned to 1000 3000 5000 7000 9000 11,000 13,000 Cumulative trap-nights maintain herbaceous vegetation. Aside from one individual of R. exulans trapped at 1800 m in remnant montane forest Figure 3: Combined species accumulation curve for native small near secondary pine forest, the non-native species were not mammals at all survey localities on the Mt. Amuyao gradient. Locali- documented in mature forest (Table 1, Figure 4). Among ties added sequentially from lowest to highest elevation, with initial sampling at each locality indicated by an arrow. Principal localities the 13 native species, five were found at disturbed locali- in mature forest are underlined. ties outside of forest. Chrotomys whiteheadi had the great- est association with disturbed habitat; it was documented at four of the five disturbed localities accounting for 11 of Summit 23 total captures (48%) for this species. Rattus everetti was 2700 recorded at two disturbed localities where six out of 26 cap- 2600 tures (23%) occurred. Apomys abrae was common in pine 2500 2400 secondary forest, accounting for five out of 42 captures 2300 (12%). Two other native species, Bullimus bagobus and Cro- 2200 cidura grayi, had singleton captures in disturbed habitat. ation (m)

v 2100 Captures for the remaining eight native species were

Ele 2000 restricted to localities in mature forest (Table 1, Figure 4). 1900 Trap success across the sampling gradient differed 1800 for the two types of bait (Table 2). At three of the eight 1700 principal localities in mature forest (1650 m, 2480 m, and 1600 2530 m) and for all localities combined, capture rates were 1500 significantly greater for ground traps baited with earth- worms compared to those with coconut. Trap success with . i i sp ay either bait was not significantly correlated with eleva- eretti ulans ys onicus icoides ys grant ys datae ys abrae tion, nor were measures of overall trap success, either ys silaceus ys maximus ys musculus ys montanus ys sor ys whiteheadi Apom Rattus ev

Apom weighted by bait type (percent success for all trap nights) Rattus ex Batom Crocidura gr Musserom Rattus tanezumi icom Apom Bullimus luz or unweighted (mean success for the two baits; Table 2). Chrotom ynchom Sor Chrotom Rh Archboldom Species differed in their responses to the two types of bait (Table 3). Earthworms were significantly more effec- Figure 4: Distributions of small mammals along the Mt. Amuyao tive than coconut in capturing four species (Apomys datae, survey gradient. Black squares denote localities in mature forest, gray squares localities in secondary pine forest, and open squares Crocidura grayi, Chrotomys silaceus, and Soricomys monta- localities in deforested second-growth habitat. nus), with two others (Archboldomys maximus and Rhyn- chomys soricoides) approaching significance. For three species (Apomys musculus, Bullimus luzonicus, and Rattus recorded below ca. 2000 m, whereas Apomys abrae, which tanezumi), coconut bait was significantly more effective, had the narrowest documented range, was not recorded and approached significance for two others (Batomys above 1800 m. The two non-native species [Rattus exulans granti and Rattus everetti). The remaining species showed (Peale, 1848) and Rattus tanezumi (Temminck, 1845)] were no significant differences in bait preference reflecting recorded only at 1800 m or lower (Figure 4). Across all local- more omnivorous food habits (e.g. Apomys abrae and ities, native species richness (the number of species docu- Rattus exulans), frequent captures in traps placed in con- mented or inferred to occur at a given locality) ranged from fined runways or at burrow openings that were unrelated 586 E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines a (p) s r -0.07 ( > 0.2) -0.43 ( > 0.2) 0.524 ( > 0.1) 0.286 ( > 0.2) 0.405 ( > 0.2) 0.928 ( < 0.01)

57 67 300 556 225 8.05 10.3 5.15 6.60 6.48 1.36 Total 3726 4922 4371 0.001 26.246

1 59 93 16 33 504 282 344 14.7 9.59 0.35 2690 11.71 10.65 10.85 0.319 0.993

40 66 12 27 13 505 631 7.92 15.4 4.28 6.10 5.90 0.97 1334 2530 0.010 6.677 Locality elevation (m) elevation Locality

4 7 1 39 47 78 7.8 325 222 3.15 7.58 8.41 1.28 2480 12.00 0.001 12.718

4 5 28 48 18 7.7 458 417 347 6.11 5.19 5.65 7.71 1.20 2300 0.592 0.287

55 10 25 49 7.7 120 610 767 9.02 6.39 7.70 7.55 1.50 1663 2100 0.069 3.302

3 7 0 0 4 8 39 82 1990

5 9 1 2 2 50 31 25 1950

9 3 1 37 30 38 7.5 187 344 4.81 8.72 6.77 7.34 2.63 1885 0.122 2.389

1 0 0 18 31 14 3.1 185 129 143 9.73 9.79 9.76 9.76 1800 0.972 0.001

3 9 0 0 6 4 115 353 1760

4 4 0 0 0 93 64 1675

6 35 74 19 26 7.5 595 938 737 5.88 3.53 4.71 4.58 2.03 1650 0.050 3.827

2 7 0 5 0 48 199 1535

0 0 0 0 0 12 63 1530

4 0 0 4 0 50 1510

2 Spearman’s coefficient, capture variables vs. elevation. vs. variables capture coefficient, Spearman’s X 0.05) are shown in bold. shown are (p < 0.05) expected than greater frequencies Capture only. localities principal for calculated rates Capture in italic. shown are forest in mature localities trapping Principal Captures/100 trap-nights Captures/100 Percent diurnal Percent Captures Nocturnal/crepuscular Trap-nights Diurnal Ground traps (earthworm) traps Ground Diel period Diel Captures/100 trap-nights Captures/100 Unweighted Captures Captures Trap-nights Weighted Trap-nights Arboreal traps (coconut) traps Arboreal Overall trap success Ground traps (coconut) traps Ground p Captures/100 trap-nights Captures/100 a Captures of native small mammals along the elevation gradient on Mt. Amuyao by bait type, trap position, and diel period. diel and position, trap type, bait by on Mt. Amuyao gradient the elevation along mammals small native of 2: Captures Table E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines 587 0.007 0.008 0.036 0.138 0.007 < 0.01 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 p-Value < 0.001 < 0.001

2 Trap postion Trap X 21.827

0 5 0 0 5 1 2 2 0 2 0 0 0 18 31 Above ground Above

0 9 1 21 51 52 24 13 40 15 12 16 46 23 276 Ground surface

0.238 0.018 0.015 0.011 0.002 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 < 0.001 p-Value < 0.001 < 0.001 < 0.001 Diel period Diel

2 X 5.967 30.302 30.295 29.895 13.494 196.062

1 4 2 0 0 0 5 1 0 1 1 1 33 10 11 Diurnal 4 0 4 17 49 24 26 13 42 31 14 15 45 22 289 Nocturnal-crepuscular

a 0.004 0.547 0.032 0.057 0.087 0.130 0.124 0.160 0.029 0.503 < 0.001 < 0.001 < 0.001 p-Value < 0.001 Bait type Bait

2 X 0.363 2.662 4.779 0.449 74.230 87.287

c 0 2 (0.23) 5 (0.16) 9 (0.37) 1 (0.03) 9 (0.25) 3 (0.09) 1 (0.03) 6 (0.21) 22 (2.10) 17 (1.72) 46 (1.25) 12 (0.32) 29 (0.79) 158 (4.31) Earthworm

4 (0.06) 4 (0.17) 6 (0.15) 5 (0.15) Coconut 29 (1.80) 11 (0.12) 21 (0.24) 25 (1.06) 11 (0.13) 19 (1.30) 17 (0.42) 11 (0.25) 31 (0.63) 15 (0.35) 136 (1.51)

b b Non-native species. Non-native Number of individuals (percent trap success in parentheses). success trap (percent individuals of Number No arboreal traps baited with earthworms. with baited traps No arboreal a b c Species Crocidura grayi Crocidura Captures of small mammal species on Mt Amuyao by trap position, bait type, and diel period. diel and type, bait position, trap by Amuyao on Mt species mammal small of 3: Captures Table Soricomys montanus Soricomys Rattus everetti Rattus Rhynchomys soricoides Rhynchomys Rattus tanezumi Rattus Apomys abrae Apomys 0.05) are shown in bold. shown are (p < 0.05) expected than greater significantly frequencies Capture Rattus exulans Rattus Apomys datae Apomys Apomys musculus Apomys Archboldomys maximus Archboldomys Batomys granti Batomys Bullimus luzonicus Bullimus Chrotomys silaceus Chrotomys Chrotomys whiteheadi Chrotomys inopinatus Musseromys 588 E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines to bait attractiveness (Chrotomys whiteheadi), or insuffi- the slender-tailed giant cloud , pallidus cient number of captures to detect patterns. Nehring, 1890, were taken at undetermined locations on Eleven species (Apomys abrae, Apomys datae, Apomys the north-facing slope of Mt. Amuyao. One was shot in musculus, Batomys granti, Bullimus luzonicus, Chrotomys mid-January in an area of montane forest with oak, pine, silaceus, Chrotomys whiteheadi, Rattus everetti, Rattus bamboo, and climbing pandan at ca. 2200 m. Two others exulans, Rattus tanezumi, and Rhynchomys soricoides) were shot at night on 19 and 20 February in montane forest had significantly greater activity during the nocturnal/ on the north slope of Mt. Amuyao, one from ca. 12 m up in crepuscular period, whereas three species (Crocidura a large tree (ca. 60 cm dbh). On 24 February, one specimen grayi, Archboldomys maximus and Soricomys montanus) of the bushy-tailed , schadenbergi were significantly diurnal. All but one of the five speci- (Meyer, 1895), taken approximately 4 km W of Barlig, was mens of Musseromys inopinatus were captured at night, shot at night from a tree ca. 5 m above the ground. Both but the sample was too small to detect a significant diel species of cloud are endemic to Luzon. C. schaden- pattern (Table 3). For the eight principal survey localities bergi is restricted to the Central Cordillera where it occurs in mature forest, the percentage of diurnal captures for in pine forest and mossy forest from 2000 to 2740 m eleva- native species was positively correlated with elevation, tion; P. pallidus is more broadly distributed in central and principally due to a nearly two-fold increase at the two northern Luzon with an elevational range from sea level to uppermost localities (Table 2). ca. 2300 m (Heaney et al. 2010, 2016, unpublished FMNH Capture frequencies by trap position (ground surface specimen records). Both species were reported to be rela- vs. arboreal) revealed differences in the climbing ability tively common on Mt. Amuyao. and habitat use of species (Table 3). Eight species (Croci- According to local hunters, long-tailed macaques, dura grayi, Apomys abrae, Apomys datae, Archboldomys Macaca fascicularis (Raffles, 1821), were uncommon maximus, Bullimus luzonicus, Chrotomys silaceus, Chroto- in montane forest and absent from higher elevations. mys whiteheadi, and Soricomys montanus) were captured ­Philippine warty pigs, Sus philippensis Nehring, 1886, on the ground more frequently than expected, indicating and Philippine deer, Cervus mariannus Desmarest, 1822, primary activity on or beneath the ground surface and were said to be uncommon, generally in areas dominated infrequent climbing. In contrast, two species (Apomys by oaks. In 2011, we observed diggings made by pigs in musculus and Musseromys inopinatus) had significantly montane forest at 1650 and 2100 m elevation. There are more arboreal captures, indicating that they are adept no museum specimen records for these three species from climbers that are primarily (if not exclusively) arboreal. Mountain Province (Heaney et al. 2010). The common palm The remaining species did not show significant differ- civet, Paradoxurus hermaphroditus (Pallas, 1777), was the ences in capture frequency; Batomys granti and Rattus only carnivore reported by local residents and we found everetti were captured more frequently on the ground, signs of their presence in 2011; there is a specimen from but arboreal captures indicated climbing abilities in both Sagada, ca. 25 km west of Mt. Amuyao (Heaney et al. 2010). species. Rattus exulans and Rattus tanezumi were cap- tured only on the ground, but this is inconclusive because both of these non-native species occurred at localities in disturbed habitats where trees were scarce and we did Discussion little or no arboreal trapping. Arboreal trapping effort was uneven across the eight principal localities in mature Mt. Amuyao and the fauna of the Central forest, but there was an overall trend of decreased arbo- Cordillera real trap success with elevation; for the five localities with more than 250 arboreal trap-nights (Table 2) there was a Species accumulation curves and the range-through perfect inverse correlation of trap success with elevation, assumption of continuous distribution suggest that further indicating a highly significant decrease in arboreal cap- sampling likely would have added species at several of tures with increasing elevation (rs = -1; p < 0.01). our sampling localities. However, the accumulation curve for the combined localities (Figure 3) indicates that sam- pling was effective in documenting most, if not all, native Large mammals species of rodents and shrews on Mt. Amuyao. Trapping revealed a rich assemblage of 13 native small mammals In 2007 we obtained specimens of two large arboreal including three previously unknown, two of which (Arch- murid rodents from local hunters. Three specimens of boldomys maximus and Musseromys inopinatus) currently E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines 589 are known only from Mt. Amuyao. Although either or both Many previous studies of small mammals (e.g. Heaney may be locally endemic, additional surveys over suffi- 2001, McCain 2005, Rowe 2009) have noted curvilinear, ciently broad elevational gradients within the Cordillera “hump-shaped” patterns of species richness across local are necessary to test this supposition. Nocturnal spotlight- elevational gradients. However, this is only the case where ing surveys would be particularly useful in documenting sampling gradients reflect the full elevational range the occurrence of arboreal species. within a region. For both Mt. Bali-it and Mt. Amuyao, the With a total of 15 species (1 shrew and 14 rodents, local gradients we were able to survey were incomplete; including the large arboreal murids, Crateromys schaden- the Mt. Bali-it gradient did not include sufficient high bergi and Phloeomys pallidus), Mt. Amuyao supports one of elevation habitat, and there were no forested localities the richest native small mammal assemblages on Luzon. In available at lower elevations on Mt. Amuyao. However, comparison, we found 14 species at Balbalasang (Rickart when combined (Figure 5), the two gradients describe a et al. 2011b), and on Mt. Data, combined historical and composite hump-shaped pattern of elevation and species recent surveys documented 17 native species (Thomas 1898, richness, from a low of five native species at ca. 1050 m on Sanborn 1952, Field Museum unpublished records). Seven Mt. Bali-it, increasing to peak values of 12 species at locali- native rodents that are endemic to Luzon have been recorded ties between 1800 and 2300 m on Mt. Amuyao, and declin- elsewhere within the Central Cordillera but were not docu- ing to nine species at 2690 m elevation near the summit mented on Mt. Amuyao: Abditomys latidens (Sanborn, of Mt. Amuyao. Furthermore, eight of the 13 species that 1952), Apomys microdon Hollister, 1913, Batomys dentatus occur above 1800 m on Mt. Amuyao are endemic to the Miller, 1911, melanurus Thomas, 1895, Carpomys Central Cordillera, and most of these are either restricted phaeurus Thomas, 1895, Soricomys kalinga (Balete et al., to, or achieve highest densities in, high elevation habitat 2006), and Tryphomys adustus Miller, 1910 (Heaney et al. (Table 1). When compared to the species richness-eleva- 2010, Balete et al. 2012). These “missing” species include tion curves for Luzon mountains we have surveyed outside some that may be restricted to other portions of the Central of the Cordillera (Rickart et al. 2011b, Heaney et al. 2013a, Cordillera (e.g. B. dentatus and S. kalinga). Others may only 2013c), it is clear that the higher mid-elevation peak for occur at elevations below our lowest sampling locality (e.g. the composite cordilleran curve is due entirely to the pres- A. microdon). Some are arboreal species that are particu- ence of these high-elevation endemic species. larly difficult to capture and thus may have eluded detec- tion (Carpomys spp.). Many of these species are simply very poorly known; this is a clear indication of the need for addi- Community structure tional intensive faunal surveys in the Cordillera. The mammals of Mt. Amuyao exhibit great morphologi- cal and ecological diversity. Among the murid rodents, Elevation and species richness the range in body size spans more than two orders of

At 2702 m, Mt. Amuyao is one of the highest mountains on Luzon. Our previous surveys revealed a clear pattern for native small mammals in which total species richness 12 increases significantly with peak elevation (Rickart et al.

2011b, Heaney et al. 2013a,c). Mt. Amuyao is nearly 500 m 10 higher than Mt. Bali-it, which at 2238 m was the highest point surveyed on the Balbalasang transect. Although we 8 would predict greater species richness on Amuyao com- pared to Bali-it, we recorded 13 small mammal species on both mountains. However, the lower end of the Mt. Amuyao Number of species 6 sampling gradient was at a higher elevation, so its actual extent was ca. 100 m less than that of Balbalasang (1197 4 0 vs. 1313 m, respectively). Equally important, the Amuyao 1000 1500 2000 2500 transect did not include elevations below 1500 m (and Elevation (m) no localities in mature forest below 1650 m). It is possible Figure 5: Species richness of native small mammals (insectivores that other species, including Apomys microdon (discussed and rodents) captured or inferred to occur at survey localities along above), are present at lower elevations near Mt. Amuyao; elevational gradients on 1) Mt. Amuyao (this study) and 2) Mt. Bali-it this can be ascertained through additional field work. (Rickart et al. 2011b). 590 E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines magnitude from Musseromys inopinatus (15–20 g) to demonstrate that native small mammal communities are Phloeomys pallidus (up to 2.6 kg). Species vary in trophic resistant to invasion by alien species, can tolerate sub- habits, spatial habitat use, temporal activity patterns, and stantial habitat disturbance, and can recover from severe adaptations to habitat disturbance. The native commu- disturbance where habitat is allowed to regenerate. These nity is dominated by narrowly endemic species that are findings call into question the general perception that restricted to the Central Cordillera region, many of which highly endemic insular faunas are uniformly suscepti- are ecological specialists. ble to disruption from disturbance and invasive species Remarkably, most of this diversity (12 of the 15 native (Rickart et al. 2011a, 2013). species) is contained within just two of the “old endemic” Although natural habitat on Mt. Amuyao is extensive clades of Philippine murid rodents (Musser and Heaney and appear to be stable, the mountain has no protected 1992). Four species (Batomys granti, Crateromys schaden- status. Local communities have long traditions of sus- bergi, Musseromys inopinatus, and Phloeomys pallidus) tainable use of forest products and wildlife, however, belong to the arboreal cloud rat that is the sister regional population growth and economic development group to the rest of the subfamily (Jansa et al. have brought changes that may have negative impacts. 2006, Heaney et al. 2009, Schenk et al. 2013). Eight The construction of telecommunications facilities on others (Apomys abrae, Apomys datae, Apomys musculus, the mountain summit has provided greater access to the Archboldomys maximus, Chrotomys silaceus, Chrotomys peak, which is now a popular destination for increasing whiteheadi, Rhynchomys soricoides, and Soricomys mon- numbers of trekkers and ecotourists. Without greater tanus) are members of the “earthworm mouse” clade protection, further development may have dire conse- (Steppan et al. 2003, Jansa et al. 2006). The remaining quences. Mt. Data National Park, where the expansion two native species (Bullimus luzonicus and Rattus ever- of commercial vegetable production has destroyed all etti) are derived from much more recent colonization of but a tiny remnant of natural forest, represents a worst- the Philippines and are members of a clade widespread in case scenario (Heaney et al. 2006). Given the anticipated Indo-Australia that includes the non-native commensal effects of climate change on the distribution of montane species Rattus exulans and Rattus tanezumi (Jansa et al. habitat in the tropics (Foster 2001) and uncertainty in 2006, Schenk et al. 2013). The phylogenetic structure of how species may respond in a topographically complex the Mt. Amuyao fauna reflects the infrequency of colo- region (Elsen and Tingley 2015), further loss of forest nization from outside the oceanic Philippines, the great on Mt. Amuyao and elsewhere in the Central Cordillera age of the Cordillera region, the early colonization of the would only augment the negative impacts on this unique region by murid rodents during the Miocene, and the regional fauna. overriding importance of autochthonous diversification in the formation of the Luzon fauna (Jansa et al. 2006, Acknowledgments: Our project was approved by the Heaney et al. 2011, 2014a, 2014b, 2016, Justiniano et al. National Commission on Indigenous Peoples (NCIP), with 2014). thanks to L Carante-Gallardo, B Masweng, R Alawas, A Olsim, V Sal-ly, WK Kalangeg, and F Falinchao. Research permits were issued by the Philippine Department of Conservation Environment and Natural Resources (DENR), and we par- ticular thank S Penafiel, TM Lim, J DeLeon, A Tagtag, C Mt. Amuyao supports an ecologically diverse mam- Custodio, and M Mendoza. We thank C Fiasnilon and J malian fauna that includes two species that may be Away of Barlig, and local residents who served as guides, restricted to the mountain, and several others that occur porters, and camp assistants. We thank N Antoque, T Ati- only in the Central Cordillera. Small mammal commu- wag, R Away, A Ayuga, J Barcelona, R Buenviaje, S Legasi, nities in forest habitats consist solely of native species, R Ngaya, R Plutado, P Puchana, J Riddell, A Reginaldo, and natives are numerically dominant even in disturbed and particularly J Sarmiento for assistance with fieldwork. forest. Some native species appear to be most abundant For assistance at the Field Museum we thank T DeCoster, where habitat is moderately disturbed and a few are J Phelps, A Niedzielski, and WT Stanley. Funding was pro- common in highly disturbed habitats including defor- vided by the Negaunee Foundation, Grainger Foundation, ested agricultural areas. In contrast, non-native species and the Barbara Brown, Ellen Thorne Smith, and Marshall rarely occur in forest, are abundant only where habitat is Field funds of the Field Museum. Research was conducted severely disturbed, and appear to be displaced by native in accordance with all relevant laws and regulations of the species where habitat is actively regenerating. Results Philippines. E.A. Rickart et al.: Mammals of Mt. Amuyao, Luzon, Philippines 591

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