Herpetofauna Diversity of The Disturbed and Isolated Bukit Maras in Terengganu, Peninsular Malaysia

22 We present the first checklist of herpetofauna in Bukit Maras based on surveys conducted from 23 2019 to 2023. Visual Encounter Surveys (VES) and drift-fenced pitfall traps were employed as 24 collection methods. Our study documented a total of 55 herpetofauna species, comprising 23 25 amphibians and 32 reptiles. Among these, the critically endangered species, Manouria emys 26 (according to the IUCN Red List) is a species of high conservation concern. The non-asymptotic 27 nature of the Species Accumulation Curve (SAC) suggests that further sampling efforts could 28 reveal additional species. Species-habitat network analysis revealed variations in species 29 composition across different habitat types. Notably, secondary forest exhibited higher 30 herpetofauna diversity compared to agricultural areas. Therefore, the conservation of remaining 31 secondary forest in Bukit Maras is crucial for preserving its herpetofauna and mitigating 32 anthropogenic impacts on this disturbed and isolated ecosystem. 33 Key words 34 Agricultural area, amphibians, anthropogenic disturbance, habitat island, reptiles, secondary 35 forest, Southeast Asia 36 Academic editor: [academic editor to complete] | publication data [copyeditor/layout editor to 37 complete] 38 Citation: [copyeditor/layout editor to complete] 39 40 Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 3

41 Peninsular Malaysia boasts remarkable biodiversity (Myers et al. 2000). However, rampant 42 deforestation threatens this richness (Sodhi et al. 2004). Driven by factors like urban sprawl, 43 logging, and agriculture, primary forest degradation has fragmented these once-continuous 44 landscapes (Hadad et al. 2015; Magintan et al. 2017). This has resulted in isolated hills 45 surrounded by human-modified areas. Research suggests these isolated hills can serve as refugia 46 for displaced amphibians and reptiles, even harboring new species discoveries (Quah et al. 2013; 47 Grismer et al. 2014a, 2016a). Documenting herpetofauna diversity in these areas is crucial before 48 local populations disappear. 49 In the Terengganu state, over 308,000 hectares of native forest have been cleared for agricultural 50 activities, primarily for oil palm, rubber plantation, and crop cultivation (Alam et al. 2012). 51 While the existing body of researches showed that many herpetofauna studies have been 52 conducted in the primary forest of this state (Grismer et al. 2013a, 2013b, 2014b, 2014c, 2015, 53 2016b, 2018; Chan et al. 2014; Sumarli et al. 2015, 2016; Nur Amalina et al. 2017; Shahirah-54 Ibrahim et al. 2018; Quah et al. 2021; Badli-Sham et al. 2023; Syafiq et al. 2023, 2024), only a 55 few have focused on the disturbed forested areas (Badli-Sham et al. 2019; Fatihah-Syafiq et al. 56 2020; Komaruddin et al. 2020). Hence, there is a significant gap in knowledge on the 57 herpetofauna of these habitats, which necessitates further study. 58 Bukit Maras (BM) is an isolated hill range surrounded by the human settlement and agricultural 59 matrix. Approximately 40% of the forested area at BM have been converted to orchards. The 60 secondary forest in these hills regenerated after the land abandonment (about 15 years ago), but 61 this area also faces the threat of deforestation due to current expansion of orchard areas. Given 62 the alarming rate of habitat loss, these disturbances could severely impact herpetofauna species 63 that may rely on these habitats as refugia. 64 Regrettably, information on the herpetofauna in this hill is virtually unknown. To our knowledge, 65 there is only a single inventory study in Bukit Maras but which focused on the chiropteran 66 species (Sulaiman and Lian 2011). The study recorded a total of 14 bat species in BM, with one 67 of the species categorized as "Near Threatened" by the IUCN Redlist. Therefore, this study aims 68 Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 4 to produce the first report of herpetofauna in BM. Bukit Maras is a non-protected area thus, this 69 investigation could provide valuable information on what species inhabit BM before we lose 70 them due to the deforestation. 71

72 Study area 73 Bukit Maras is situated in the Kuala Nerus district, Terengganu, surrounded by human settlement 74 and agricultural areas (Fig. 1). It has a total of approximately 2200 hectares of land comprised of 75 agricultural areas, secondary forest, and primary forest (underexplored). 76 There are three main sampling sites: 77 • Site 1 (5°25'20.98"N 103°1'18.18"E) – This hill has a large soil road from the foothill to 78 the summit as a hiking trekking trail. The landscape is characterized by an agricultural 79 matrix and an open area for car parking at the foothill. Crop plantation areas also can be 80 found along the trekking trails up to 200 meters. Examples of the planted crops are durian 81 trees (Durio spp.), petai trees (Parkia speciosa), and banana plants (Musa spp.). Two 82 disturbed small streams can be found in the agricultural areas, which originated from the 83 intact secondary and primary forest. 84 • Site 2 (5°24'33.77"N 103°1'27.63"E) – This hill also has a large soil road from the 85 foothill to the summit as a hiking trekking trail. Oil palm and rubber plantations are the 86 primary agricultural plantations here. Secondary forest vegetation situated mainly at the 87 peak. A disturbed small stream flow through the agricultural area. 88 • Site 3 (5°24'35.4"N 103°00'47.4"E) – This site is a secondary forest characterized by a 89 small stream covered by a few dipterocarp tree species left undisturbed from 90 deforestation in the previous years. This site has the minimal disturbance compared to 91 other two sites but the threat of deforestation for orchard expansion is imminent. 92 Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 5 93 Figure 1. A. Location of Bukit Maras in Terengganu, Peninsular Malaysia. B–C. QGIS 94 generated map showing the area of BM surrounded by the agricultural, rural, and urban areas. 95 Sample collection and preservation 96 The surveys were conducted opportunistically from July 2019–October 2019, 4 July 2020, 12 97 July 2020, 26–27 July 2020, 17 October 2020, 12–14 November 2020, 1 November 2020, 26 98 November 2020, 28 November 2020,15 January 2021 and between 31 December 2022 to 11 99 March 2023. Initially, pilot surveys were done opportunistically in 2019, and a systematic survey 100 was in the planning for the subsequent years but due to the Covid 19 situation during the former 101 years (2020–2021), opportunistic surveys approach was implemented at this site to standardize 102 the sampling effort. Surveyed areas spanned the disturbed and undisturbed small streams, 103 secondary forests, and agricultural areas. The primary forest was remained untapped due to its 104 inaccessibility. We sampled 13 sampling points grouped into four categories: agricultural area 105 (AA); secondary forest (SF); agricultural area stream (STA); secondary forest stream (STF) 106 (Table 1). We divided the habitat types into these four categories as we expect these four habitat 107 types will consist of different species composition and demonstrate the importance of each 108 habitat for this species. 109 South China Sea Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 6 Table 1. Habitat categories studied in Bukit Maras 110 Habitat Characteristics Sampling Site Sampling Point Agricultural area Mainly composed of durian (Durio sp.), banana (Musa sp.), petai (Parkia speciosa), oil palm (Elaeis guineensis) and rubber (Hevea brasiliensis) plantation. Scatterly located from the foothill up to elevation of 200 metres a.s.l. Site 1, Site 2 4 Secondary forest Forest remnants composed mainly of native species, unmanaged environment, with formation of understory and canopy. All sites 4 Agricultural area stream Small stream in the agricultural area with no canopy formation Site 1, Site 2 3 Secondary forest stream Small stream in the agricultural area with canopy formation Site 1, Site 3 2 111 A B Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 7 C D E F Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 8 Figure 2. Habitat types in Bukit Maras A–D. agricultural area E. secondary forest F. stream at 112 secondary forest G–H. stream at agricultural area. 113 To maximize the sampling effort, three types of collecting methods were employed: Visual 114 Encounter Survey (VES), drift-fenced pitfall traps, and acoustic sampling. The samplings were 115 executed during the day (10:00 to 13:00 h) and at night (20:00 to 23:00 h) to record both diurnal 116 and nocturnal species. The VES activities were conducted with search parties consisting of three 117 to four persons. This method was executed during the day and night to sample diurnal and 118 nocturnal species in the area. A set of pitfall traps consisted of three 18L buckets and aluminum 119 zinc as the fence. The buckets were buried two meters apart from each other and were arranged 120 in approximately straight lines. Two sets of pitfall traps were set up randomly at different 121 locations. The first one was deployed at the foothill near the agricultural area, and the second set 122 was deployed at the hilly area in the secondary forest. The vocalization method also was used to 123 record the species based on the frog calls. The recorded sound can be used for species-specific 124 sound characteristic description in future study (Chan et al., 2020; Quah et al., 2021). A total of 125 816 man-hours (204 hours/person) were spent for the herpetofauna surveys. 126 Captured specimens were identified based on their morphological characteristic, following Berry 127 (1975) for amphibians, Grismer (2011) for lizards, Auliya (2007) for freshwater turtles and 128 tortoises, and Das (2012) for snakes. Photographs of live specimens were taken with the Canon 129 3000D and Sony A6000 digital cameras. Amphibian nomenclature follows the Amphibian 130 Species of the World database (Frost 2024), while the reptile nomenclature follows The Reptile 131 Database (Uetz et al. 2023). Only a few samples were taken for voucher specimens to minimize 132 G H Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 9 the extirpation of the current population. Euthanized voucher specimens were then preserved 133 with 10% formalin before being transferred into 70% ethanol for long-term storage and 134 deposited at the General Biology Lab, Universiti Malaysia Terengganu, and catalogued under 135 UMT Zoological Collection (UMTZC). 136 Data analysis 137 The individual-based and coverage-based rarefaction and extrapolation analysis was constructed 138 by using the “iNEXT” R package (Hsieh et al. 2016) to determine the adequacy of our sampling 139 effort at BM and for both amphibian and reptile groups. The sampling achieves completeness 140 when the curve is plateauing for the former and achieve completeness value which is 1.0 for the 141 latter. This analysis permits comparison of diversity with Hill numbers of order q for unequal 142 sampling effort between two or more sites or groups. There are three types of order q for Hill 143 numbers namely, species richness (q=0), Shannon’s diversity (q=1) and Simpson’s diversity 144 (q=3). We only utilized diversity order of species richness (q=0) for this study. We also used this 145 analysis to compare the herpetofauna diversity between the four habitat types. For the 146 comparison of habitat types, we combined both amphibians and reptiles data as herpetofauna 147 data to utilize in the comparison analysis. Non-overlap curves strongly indicate significant 148 difference and vice versa for both individual-based and coverage-based rarefaction and 149 extrapolation curves. 150 For species-habitat network, we built two networks using both abundance and incidence data 151 acting as links while habitat types and herpetofauna species acting as nodes (Marini et al. 2019). 152 The analysis was performed using the “bipartite” R package (Dormann et al. 2009). All analyses 153 were executed in RStudio software (RStudio Team 2023). 154

155 A total of 55 herpetofauna species from six amphibian families (Bufonidae – 2 spp., 156 Dicroglossidae – 5 spp., Megophryidae – 3 spp., Microhylidae – 4 spp., Ranidae – 5 spp., 157 Rhacophoridae – 4 spp.) and nine reptile families (Agamidae – 7 spp., Gekkonidae – 7 spp., 158 Scincidae – 4 spp., Varanidae – 1 spp., Colubridae – 9 spp., Pythonidae – 1 spp., Viperidae – 1 159 Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 10 spp., Trionychidae – 1 spp., Testudinidae – 1 spp.) were recorded in this study (Table 2). Based 160 on IUCN Redlist (2024), there is only single species (Manouria emys) listed under "Critically 161 Endangered" status in this study, whereas the rest of the species are categorized as "Least 162 Concern". 163 Table 2. A species checklist of amphibians and reptiles recorded in Bukit Maras and their IUCN 164 status. 165 No Taxa IUCN AMPHIBIANS Bufonidae 1 Duttaphrynus melanostictus (Schneider, 1799) LC 2 Ingerophrynus parvus (Boulenger, 1887) LC Dicroglossidae 3 Fejervarya limnocharis (Gravenhorst, 1829) LC 4 Limnonectes blythii (Boulenger, 1920) LC 5 Limnonectes deinodon Dehling, 2014 LC 6 Limnonectes hascheanus (Stoliczka, 1870) LC 7 Limnonectes malesianus (Kiew, 1984) LC Megophryidae 8 Leptobrachella sola (Matsui, 2006) LC 9 Leptobrachium hendricksoni Taylor, 1962 LC 10 Pelobatrachus nasuta (Schlegel, 1858) LC Microhylidae 11 Kaloula pulchra Gray, 1831 LC 12 Microhyla berdmorei (Blyth, 1856) LC 13 Microhyla heymonsi Vogt, 1911 LC 14 Microhyla mantheyi Das, Yaakob & Sukumaran, 2007 LC Ranidae 15 Humerana miopus (Boulenger, 1918) LC 16 Hylarana glandulosa (Boulenger, 1882) LC 17 Hylarana labialis (Boulenger, 1887) LC Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 11 18 Hylarana laterimaculata (Barbour & Noble, 1916) LC 19 Hylarana nicobariensis (Stoliczka, 1870) LC Rhacophoridae 20 Nyctixalus pictus (Peters, 1871) LC 21 Polypedates discantus Rujirawan, Stuart & Aowphol, 2013 LC 22 Polypedates leucomystax (Gravenhorst, 1829) LC 23 Theloderma licin McLeod & Ahmad, 2007 LC REPTILES LIZARDS Agamidae 24 Acanthosaura armata (Gray, 1827) LC 25 Bronchocela cristatella (Kuhl, 1820) LC 26 Calotes versicolor (Daudin, 1802) LC 27 Draco sumatranus Schlegel, 1844 LC 28 Gonocephalus grandis (Gray, 1845) LC 29 Gonocephalus liogaster (Günther, 1872) LC 30 Leiolepis belliana (Hardwicke & Gray, 1827) LC Gekkonidae 31 Cyrtodactylus consobrinus (Peters, 1871) LC 32 Cyrtodactylus quadrivirgatus Taylor, 1962 LC 33 Gehyra mutilata (Wiegmann, 1834) LC 34 Gekko monarchus (Schlegel, 1836) LC 35 Hemidactylus frenatus Duméril & Bibron, 1836 LC 36 Hemidactylus platyurus (Schneider, 1797) LC 37 Hemiphyllodactylus typus Bleeker, 1860 LC Scincidae 38 Dasia olivacea Gray, 1839 LC 39 Eutropis multifasciata (Kuhl, 1820) LC 40 Lipinia vittigera (Boulenger, 1894) LC 41 Lygosoma siamensis Siler, Heitz, Davis, Freitas, Aowphol, Termprayoon & Grismer, 2018 LC Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 12 Varanidae 42 Varanus salvator (Laurenti, 1768) LC SNAKES Colubridae 43 Ahaetulla prasina (Boie, 1827) LC 44 Boiga cynodon (Boie, 1827) LC 45 Dendrelaphis caudolineatus (Gray, 1834) LC 46 Dendrelaphis cyanochloris (Wall, 1921) LC 47 Dendrelaphis pictus (Gmelin, 1789) LC 48 Dendrelaphis striatus (Cohn, 1905) LC 49 Gonyosoma oxycephalum (Boie, 1827) LC 50 Lycodon subcinctus Boie, 1827 LC 51 Pseudorhabdion longiceps (Cantor, 1847) LC Pythonidae 52 Malayopython reticulatus (Schneider, 1801) LC Viperidae 53 Tropidolaemus wagleri (Boie, 1827) LC FRESHWATER TURTLE AND TORTOISE Testudinidae 54 Manouria emys (Schlegel & Müller, 1844) CR Trionychidae 55 Dogania subplana (Geoffroy Saint-Hilaire, 1809) LC Notes: IUCN STATUS: LC = Least Concerned; CR = Critically Endangered. 166 Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 13 A C D E F B Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 14 Figure 3. Amphibians from Bukit Maras A. Duttaphrynus melanostictus B. Ingerophrynus 167 parvus C. Fejevarya limnocharis D. Limnonectes deinodon E. Leptobrachium hendricksonii F. 168 G H I K L J Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 15 Megophrys nasuta G. Microhyla heymonsi H. Microhyla mantheyi I. Humerana miopus J. 169 Hylarana labialis K. Polypedates leucomystax L. Theloderma licin 170 A C D E F B Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 16 Figure 4. Lizards from Bukit Maras A. Acanthosaura armata B. Bronchocela cristatella C. 171 Calotes versicolor D. Gonocephalus grandis E. Gonocephalus liogaster F. Leiolepis belliana G. 172 Cyrtodactylus consobrinus H. Cyrtodactylus quadrivirvagtus I. Gekko monarchus J. 173 Hemiphyllodactylus typus K. Lygosoma siamensis L. Lipinia vittigera 174 G H I K L J Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 17 A C D E F B Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 18 Figure 5. Freshwater tortoise and turtle and snakes from Bukit Maras A. Ahaetulla prasina B. 175 Boiga cynodon C. Dendrelaphis caudolineatus D. Dendrelaphis cyanochloris E. Dendrelaphis 176 pictus F. Dendrelaphis striatus G. Gonyosoma oxycephalum H. Lycodon subcinctus I. 177 Malayopython reticulatus J. Tropidolaemus wagleri K. Manouria emys L. Dogania subplana 178 G H I K L J Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 19 The individual-based rarefaction and extrapolation curves for the total herpetofauna and each of 179 amphibian and reptilian assemblages implied that additional species can be detected in BM when 180 more sampling efforts are executed as the extrapolated curves for all three showed no sign of 181 plateauing just yet. At the extrapolated curves, it is estimated that 60 herpetofauna species can be 182 discover in BM, which to be specific a potential discovery of an additional two species of 183 amphibians and three species of reptiles with additional efforts. Coverage-based rarefaction and 184 extrapolation curves are in accord with the individual-based rarefaction and extrapolation curves 185 as the curves approaching the sampling completeness value. All curves are non-overlapped 186 which indicated that the species richness (q=0) for all curves are significantly different. 187 188 Figure 6. A. Individual-based rarefaction (solid line segment) and extrapolation (dotted line 189 segment) sampling curves with 95% confidence interval (shaded areas) (left panel) and B. 190 coverage-based rarefaction (solid line segment) and extrapolation (dotted line segment) sampling 191 curves with 95% confidence interval (shaded areas) (right panel) for herpetofauna sampled in 192 Bukit Maras, Terengganu, Peninsular Malaysia. 193 In general, the Calotes versicolor had the highest abundance compared to other species in Bukit 194 Maras. It also contributed the highest number of individuals in agricultural area (AA). The AA is 195 also the site with the highest number of individuals occupied by the herpetofauna. Species 196 richness-wise, the seconday forest (SF) had the highest number of species among the habitats. 197 The Fejevarya limnocharis had the highest number of frequency as it can be found across all 198 four habitats. Each of the habitat type composed of different set of species composition (Fig. 7). 199 In specific, there are 36 species of herpetofauna in SF and the highest number of individuals is 200 Eutropis multifasciata (12 individuals), followed by Microhyla heymonsi (11 individuals) and 201 A B Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 20 Limnonectes hascheanus (7 individuals). Meanwhile, AA had only 17 species and dominated by 202 C. versicolor (68 individuals), followed by Hemidactylus frenatus (17 individuals) and 203 Duttaphrynus melanostictus (15 individuals). For riparian areas, stream of secondary forest 204 (STF) had 16 species, and dominated by Limnonectes deinodon (36 individuals), followed by 205 Hylarana labialis (25 individuals) and Leptobrachium hendricksoni (16 individuals). On the 206 other hand, stream of agricultural area (STA) had only nine species, dominated by Polypedates 207 leucomystax (23 individuals), followed by Fejevarya limnocharis (19 individuals) and H. labialis 208 (17 individuals). 209 Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 21 Figure 7. Species-habitat network in Bukit Maras. A. Abundance-based species-habitat network 210 B. Incidence-based species-habitat network. The left panel represents nodes for habitat types 211 while the right panel represents nodes for each species. The width of the links represents the 212 A B Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 22 number of individuals (abundance-based) and frequency of occurrence (incidence-based). The 213 nodes are arranged from the highest to lowest (abundance/frequency). 214 The diversity order of species richness (q=0) for both curves for secondary forest (SF) and 215 secondary forest’s stream (STF) are not yet approaching asymptote even at the extrapolated 216 curves indicating that more species can be discovered in both habitats. On the other hand, both 217 curves for agricultural area (AA) and agricultural area’s stream (STA) showed a sign of levelling 218 off at the extrapolated curves indicating that the sampling in these areas are almost complete. 219 220 Figure 8. A. Individual-based rarefaction (solid line segment) and extrapolation (dotted line 221 segment) sampling curves with 95% confidence interval (shaded areas) and B. coverage-based 222 rarefaction (solid line segment) and extrapolation (dotted line segment) sampling curves with 223 95% confidence interval (shaded areas) for the herpetofauna data of four habitat types: green 224 (secondary forest); red (agricultural area). The solid dots/triangles represent the reference 225 samples. Hill numbers of order (q = 0) or species richness was measured for both curves. 226

227 The forested area at the human-induced landscape is disappearing at an unprecedented rate, 228 leaving "islands" of forest remnants (Sodhi et al. 2010). This habitat may become refuge to the 229 perturbed herpetofauna and our study demonstrated that by documenting a total of 55 species of 230 herpetofauna in Bukit Maras. This record is a preliminary checklist and additional species record 231 in this baseline data is promising, as indicated by the non-asymptotic individual rarefaction and 232 extrapolation curves. The extrapolated curves indicated that an additional five herpetofauna 233 Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 23 species can be found with additional efforts. Some species of herpetofauna particularly snakes 234 can be elusive and previous study on temporal snake diversity in Terengganu suggested that 235 surveys should be intensified especially during the raining season (Syafiq et al. 2023). This 236 would not only increase the chance to encounter elusive snake species but as well as amphibian 237 species (Badli-Sham et al. 2023). 238 Bukit Maras is a disturbed landscape dominated by secondary forest and agricultural areas. 239 Herpetofauna are sensitive to land-use changes (Sodhi et al. 2008). The ongoing orchard 240 expansion threatens the discovery of new species and the persistence of elusive ones. Our 241 findings, aligning with previous research, show that secondary forests have higher herpetofauna 242 diversity compared to agricultural areas (Fig. 8). This difference is likely due to species loss in 243 agricultural areas, where suitable habitat is limited (Fig. 7). Forest-dwelling herpetofauna, known 244 for their high site fidelity (Vitt and Caldwell 2001; Hillers et al. 2008), are particularly 245 vulnerable to local extirpation in such modified habitats. Studies in oil palm plantations 246 (Gillespie et al. 2012; Faruk et al. 2013) demonstrate a similar pattern, with generalist species 247 dominating disturbed areas. Our results in the agricultural areas of Bukit Maras reflect this trend. 248 Without action to curb orchard expansion, biotic homogenization, where species diversity 249 reduced and dominated by only a few common species, is a looming threat. 250 The presence of the critically endangered species, Manouria emys tortoise in the secondary forest 251 highlights the high conservation value of Bukit Maras' remaining forests. This discovery 252 underscores the urgency for immediate action by policymakers, local authorities, and the public 253 to protect these vital habitats. 254 Given the widespread occurrence of secondary forests around human settlements, practical 255 conservation efforts should focus on preserving these areas and their riparian zones (Chazdon et 256 al. 2009; Pirnat and Hladnik 2016). While not a perfect substitute for primary forests, secondary 257 forests can support a significant diversity of herpetofauna (Thompson and Donnelly 2018). Their 258 mix of vegetation and microhabitats from both primary and disturbed forests creates a more 259 favourable environment for herpetofauna compared to other human-modified landscapes (Luja et 260 al. 2008). Protecting these secondary forests can serve as a buffer zone, mitigating anthropogenic 261 disturbances and safeguarding the remaining herpetofauna in Bukit Maras. 262 Author-formatted, not peer-reviewed document posted on 14/03/2024. DOI:  https://doi.org/10.3897/arphapreprints.e122806 24

263 Our study helps fill a critical knowledge gap by investigating the herpetofauna of isolated hills 264 within Terengganu's human-modified landscape. This research focused on Bukit Maras, but 265 similar isolated hills in Terengganu, such as Besar Hill, Chendering Hill, and Jong Hill, warrant 266 further investigation using similar methods. Further surveys in Bukit Maras' northern region 267 could reveal additional species. This study provides valuable baseline data for future monitoring 268 efforts to assess the impacts of environmental changes on herpetofauna in human-modified 269 landscapes. 270

271 We thank Universiti Malaysia Terengganu for the research equipment used during this study. 272 The first author (MFS) is deeply grateful for the Tuanku Canselor Scholarship, generously 273 funded by Universiti Malaysia Terengganu, which greatly supported first author throughout his 274 study. We also thank to all undergraduate students for their assistance in the field. The 275 Department of Wildlife and National Parks is dully acknowledged for permission to conduct this 276 study (Permit no.: T-00563-16-17). We thank the anonymous reviewer for their helpful 277 comments. 278 Authors’ Contributions 279 MFS collected the data, served as authority on species identification, provide photograph of the 280 specimens, analyzed the data, wrote, and revised the manuscript. BHBS collected the data, 281 served as authority on species identification, provide photograph of the specimens and 282 constructed the map figure. SAF, MIMAW, MAN, FHA, GK, NNS, NFN, MS-R, JA, TKL, 283 NSX, MFA, SAR collected the data. ABA conceptualized the study design, analyzed the data 284 and revised the manuscript. 285

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