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email: Graeme.Gillespie@nre.vic.gov.au

Sulawesi, Indonesia, is a large equatorial island with a rich and diverse herpetofaunal assemblage. More than 110 reptile and 46 frog species have been recorded from the island to date, many of which are endemic (Iskandar and Nio 1996). However, despite this high level of endemicity and the biogeographical significance of the region, relatively few surveys have been undertaken of the herpetofauna of Sulawesi and associated smaller islands. Therefore these figures are likely to be conservative estimates of the species richness of Sulawesi. Approximately half of the frog taxa known from Sulawesi have been discovered in the past 15 years, and many are yet to be formerly described. New reptile species have also been discovered in recent years. In addition, the systematics of several other reptile groups requires further resolution, and the status of a number of species in the region requires clarification. The conservation status of many poorly known taxa is also unclear. Consequently there is a great need for further surveys of the herpetofauna of the region.

In 2000 Operation Wallacea commenced a herpetofauna survey in south-east Sulawesi. This survey was conducted as part of a general base-line biodiversity survey. This year, surveys were conducted on Buton Island, with a limited survey of Hoga Island in the Wakatobi Marine National Park, where Operation Wallacea’s marine projects are based. The primary aims of this study were to:

· refine sampling strategies for herpetofauna surveys in the region

· generate species lists for specific areas/regions

· collect voucher specimens of any new or poorly-known taxa

· collect baseline information on relative abundance and habitat associations of species

· provide a basis for further expanded surveys and a herpetological research program to further advance knowledge of the status and biology of the herpetofauna, and ultimately contribute to biodiversity conservation programs in the region.

 

The survey was based in the vicinity of Labundo Bundo in central Buton Island (Fig. 1). Sampling was conducted between early July and late September 2000. Some limited sampling was also conducted on Hoga Island in the Wakatobi Marine Park. A variety of methods were employed to sample the herpetofauna.

Pitfall traps were established at 16 sites in a variety of habitats (Fig. 1). Each trap-line comprised five 45 L buckets imbedded in the ground, spaced 5 m apart, with a 1 mm gauge wire mesh drift fence 30 cm high and 20 m long, passing over the centre of each bucket. Pitfall trap sites were chosen to sample the range of broadly-distinct habitat types within the region. These included terraces and mid-slopes in rainforest with varying levels of human disturbance, including selective logging and rattan harvesting, and several sites in highly disturbed habitats, such as regenerating cleared forest and plantations. Pitfall traps were checked every morning and operated for varying lengths of time, ranging from two to four weeks.

Transects 100 m long were established at 30 sites, including most pitfall sites. Diurnal censuses were conducted for reptiles along each transect. This was involved one person slowly walking along the transect, pausing at regular intervals, and recording the numbers of each species observed. Each transect was censused five times during the following daytime intervals: early morning, late morning, midday, early afternoon and late afternoon.

Figure 1. Map of the Labundo Bundo region, showing approximate localities of pitfall sites.

Opportunistic searches were conducted for reptiles over a wider area. These searches generally comprised walking slowly through various habitats, such as forests, along streams, mangroves, agricultural areas or swamps, looking for active reptiles, and disturbing logs, rocks or other ground debris to check for sheltering animals.

Nocturnal searches were conducted for frogs and reptiles. These searches were mostly targeted at, or near, aquatic environments such as streams, swamps or rice paddies, but nocturnal searches, specifically targeting geckos and snakes, were also conducted in other forest habitats and caves.

Stream transects were established at 11 sites in the Labundo Bundo area for standardised censuses of the relative abundance of riverine frog species.

Voucher specimens of most taxa detected were collected to confirm field identification, to aid identification of unknown species or suspected new species, and to collect material for taxonomic groups requiring further systematic resolution. These specimens will be lodged with the National Museum in Bogor.

On Hoga Island, only diurnal and nocturnal opportunistic searches were conducted.

Nomenclature follows that used by Bosch (1985), Iskandar & Nio (1996), and Manthey & Grossman (1997).

A total of 45 species of herpetofauna were detected in the Labundo Bundo region (Table 1). This comprised 12 species of frog from the families Ranidae, Bufonidae, Microhylidae and Rhacophoridae, 17 species of snake (Colubridae, Crotalidae, Cylindrophidae, Pythonidae and Typhlopidae), 1 turtle species (Bataguridae) and 15 lizard species (Agamidae, Gekkonidae, Scincidae and Varanidae). Eight reptile species (Colubridae, Hydrophidae, Typhlopidae, Pythonidae, Gekkonidae and Varanidae) and one frog species (Ranidae) were located on Hoga Island. The combined total number of species encountered in the region during this expedition was 47 (Appendix I).

At least one frog species (Rhacophorus sp.) is new to science. Two other taxa (Oreophryne sp. and Polypedates sp.) may also be undescribed species (D. Iskandar, Bandung, pers.com.). The identity of two riverine species, Limnonectes inflatus and L. modestus are tentative, and the taxonomic identity of these frogs requires further resolution. The taxonomic identities of one Draco and Gehyra sp. have also not yet been determined.

Based upon the overall species accumulation rate throughout the survey period, it is likely that most of the species in the Labundo Bundo area were detected during this study. However, there was a marked reduction in the species accumulation rate after week four, corresponding to the commencement of the dry season (Fig. 2). Given the small area covered by the survey, more species are likely to be added if other regions of Pulau Buton were to be surveyed.

Information on detailed habitat classes within the region was not available, and time was not available for extensive systematic classification of habitats at all sampling sites. However, several broad habitat classes were identified, which are useful for describing herpetofauna community composition. These included: Relatively undisturbed forest, significantly disturbed forest, riparian forest, plantations and fields, and villages.

The structure of forested habitats around Labundo Bundo varied with respect to tall canopy cover and understorey and mid-storey development. A variety of factors probably contributed to determining the structural variation, but much of this variation appeared to be related to varying levels of anthropogenic disturbance associated with timber harvesting. Selective timber harvesting is practised in the region. Individual trees are felled, planks are cut on site and transported out of the forest on foot. Areas of recent selective logging were fairly obvious but earlier disturbance history was less so. Nevertheless, forest areas could be broadly classified as significantly disturbed, based on obvious evidence of selective logging, large canopy gaps and absence of large trees; or less disturbed, where tall trees remained, canopy gaps were small and evidence of logging was lacking.

Riparian forest refers to forested habitats associated with streams in either disturbed or undisturbed forest areas. Aquatic and riverine habitats are distinctive features in the landscape and are key habitats for many reptile and amphibian species. As such they have been distinguished from other forest habitats

The highest numbers of species were found in forest habitats (significantly- or less-disturbed), and the lowest number in mangroves (Table 1). However, this discrepancy may reflect biases in survey effort between these broad habitat types. For instance, most pitfall trap lines and transect searches were conducted in forest habitats. Only one pitfall trap line was established in mangrove habitat.

Table 1. Broad habitat classes in which reptile and amphibian species were located in the Labundo Bundo region, Pulau Buton.

Figure 2. Cumulative number of reptile and amphibian species detected each week of survey in the Labundo Bundo area.

Most species were found across a broad range of habitat types. Thirteen species were found both in forested and grossly-modified habitats (i.e., fields, plantations or villages). Twenty four species were only recorded in forest habitats (disturbed, less disturbed or riparian). Of these species, only three were restricted to less-disturbed forest. Six species were restricted to grossly-modified habitats.

With the exception of microhylids, all frog species were found near streams (Table 1). The microhylids were found in non-riparian forest habitats. Five species of frog were restricted to stream habitats, two of which (Limnonectes inflatus and Rhacophorus sp.) bred in streams during the survey. Three other species (Bufo celebensis, Rana chalconata and Limnonectes modestus) also bred in streams during the survey, but adults were found throughout the forest. Polypedates leucomystax and Fejervarya cancrivora bred in lentic habitats, such as swamps, rice paddies and wells, during the survey.

Pitfall trapping proved to be an effective technique for detecting small, predominantly terrestrial reptile and frog species. Twelve reptile and five frog species were detected using this method. Seven species were only detected using this technique. These included one frog (Oreophryne sp.), four snake (Calamaria spp. and Typhlopidae) and three skink species (Table 2).

Diurnal transect censusing was a relatively ineffective technique. Only five reptile species were located using this approach, all of which were detected using other methods. Opportunistic searches were the most effective technique for detecting larger species, such as snakes, monitor lizards and arboreal reptile species (Table 2).

Nocturnal censusing was the primary technique for detecting frogs, however, microhylid species were only detected by pitfall trapping or incidental observation. Nocturnal censusing was relatively ineffective for detecting snakes, despite the number of nocturnally-active species known from the region.

Most species were detected incidentally during the survey. Thirteen snake species were detected through incidental observation; three of these only in this way.

Pitfall trapping was biased towards trapping smaller species and those that could not jump or climb out of the buckets(Table 3). The largest snake species captured in pitfall traps was Psammodynastes pulverulentus (Mock Viper) which was approximately 40 cm in length. Only a single arboreal frog was captured using this method (Rana chalconata). However, this technique provided reasonably systematic sampling of the small terrestrial component of the herpetofauna.

The relative abundance of small terrestrial species varied markedly; Sphenomorphus textum and Mabuya rudis were the most frequently-trapped species. Other species, such as Lipina infralineolatum and Sphenomorphus nigrolabris, were recorded infrequently (Table 3). There was a strong correlation between the trapping frequency of a species and the number of sites at which that species was trapped (r = 0.935, d.f. = 16, p < 0.0001; Fig. 3). This suggests that the probability of detection of species varies substantially, and that species detected at low frequency may be more widespread across trapping sites than indicated by this study.

The total number of species detected by pit trapping was 17, but the maximum number detected at an individual site was eight. There was no significant relationship between number of trap nights and the number of species detected at a site (r = 0.409; d.f. = 15, p = 0.116). The number of species accumulated per night, averaged across all sites, increased consistently over the first 12 days of trapping, then slowed substantially (Fig. 4). This suggests that, in this region, pitfall trap sites should be maintained for a minimum of approximately two weeks to detect most species present at a site.

Figure 3. Log₁₀ relationship between the overall number of individuals recorded from pitfall captures and number of sites at which each species was captured.

Table 2. Reptile and amphibian species recorded by various sampling techniques in the Labundo Bundo area, Pulau Buton.

Table 3. Number of each species of herpetofauna recorded at 16 pitfall trap sites around Labundo Bundo.

Habitat abbreviations are derived from habitat classes in Table 1.

Figure 4. Means and standard errors of species accumulation rates across all pitfall trap sites.

Varanus salvator (monitor lizard)

Uncommon but widespread throughout the region. Individuals observed along roads and tracks though a range of forest habitats, coastal habitats, fields and plantations. Also common on Pulau Hoga.

Draco sp. (flying lizard)

Taxonomic identity yet to be confirmed. Possibly two species present in the region. Individuals were commonly observed on tree trunks in plantations and around the village. Infrequently observed in forest and on tree trunks near water courses.

Cosymbotus platyurus (house gecko)

One individual observed in a house in Labundo Bundo. Common in buildings in Bau Bau.

Cyrtodactylus jellesmae (forest gecko)

Common and widespread throughout highly disturbed and less disturbed forest and riparian habitats. Frequently observed on tree trunks or low-vegetation at night.

Gyhyra mutilata (common house gecko)

Abundant in Labundo Bundo and other buildings on Pulau Buton and Pulau Hoga. Numerous individuals seen on buildings. Restricted to human settlement.

Gehyra sp.

Taxonomic identity yet to be resolved. One individual captured in a tree adjacent to the large river to the north-east of Labundo Bundo.

Gecko gecko (tokay)

Uncommon around Bau Bau. One individual heard in Labundo Bundo. Abundant on Hoga around buildings and in surrounding forest habitats.

Sphenomorphus textum (forest skink)

Common and widespread throughout all forested habitats in the Labundo Bundo region. This was the most abundant species of reptile in the area. Frequently observed basking or scuttling on the forest floor and on forest tracks.

Sphenomorphus nigrolabris (forest skink)

Rare in the survey area. One adult and two juveniles captured in pitfall traps, and one adult observed during transect censuses. Restricted to forest habitats.

Common throughout forest habitats. Also found in plantation areas with dense undergrowth. This is a fossorial species that inhabits forest litter, and is rarely seen during the day.

One individual captured in a pitfall line in relatively undisturbed forest in the Kakanawe Reserve. This species is probably also fossorial, inhabiting forest litter, and nocturnal or crepuscular.

Restricted to the coastal fringe where it inhabits mangroves and associated habitats

Arboreal species restricted to villages and plantations. Observed on trunks of palm trees and roofs of houses. Relatively common in the Labundo Bundo area.

Common and widespread throughout all forested habitats, riparian areas, fields and plantations. This is a predominantly terrestrial species, which may venture 1 – 2 m up trunks of large trees. It is a diurnal species, frequently observed basking or foraging in sunlight patches associated with canopy gaps and near fallen timber.

Restricted to the villages and surrounding fields and plantations, such as Labundo Bundo. Also recorded in fields north-west of the Kakanawe Reserve, and along the coastal fringe.

Typhlops ater (blind snake)

Uncommon and restricted to forest habitats. Two individuals captured in pitfall traps.

Ramphotyphlops braminus (blind snake)

Uncommon but widespread. Several individuals captured in pit traps and several found on roads in plantations and in Labundo Bundo.

Trimeresurus wagleri (pit viper)

Uncommon, restricted to forest habitats. One individual found in the Kakanawe Reserve. Two individuals found on the jungle training course, near Kapantori.

Python reticulatus (reticulated python)

Uncommon but widespread. Several individuals were found in the vicinity of Labundo Bundo and surrounding forest habitats. Several individuals observed in forested habitats and riparian habitats at night. Two specimens, one approximately 6 m long, were killed by villagers in Kaweli during the survey.

Cylindrophis melanotus (red-bellied pipe snake)

Uncommon. One individual collected by a villager in Labundo Bundo; one road-killed specimen collected from the start of the Tarsius Trail; and one individual found crossing the Tarsius Trail in the Kakanawe Reserve.

Dendrelaphis p. pictus (painted tree snake)

Relatively common and widespread. Several individuals seen in Labundo Bundo and along streams through plantations and forest habitats

Rhabdophis chrysargoides (keelback)

Uncommon. Two sub-adults found in the Kakanawe Reserve

Xenochrophis piscator melanzostus (keelback)

Two individuals found along major streams to the north-east of Labundo Bundo.

Sinonatrix trianguligera (brown keelback)

Uncommon but widespread in forest habitats near streams. One individual found along a stream north-west of the Kakanawe Reserve. Several individuals found near the primary forest base camp south of Labundo Bundo. One individual found on the Old Dutch House Trail.

Common in forest habitats. Over 30 individuals captured. Detected at most pit trap sites.

Relatively uncommon and restricted to forest habitats. Two individuals captured at different pit trap sites.

Ahaetulla p. prasina (common green whipsnake)

Common around Labundo Bundo and surrounding plantations. Several individuals recorded in less disturbed forest in the Kakanawe Reserve

Two individuals recorded in a cave on the road near Kaweli.

E. erythrura celebensis (rat snake)

Uncommon. Several individuals observed around Labundo Bundo and along the road to Kaweli.

Chrysopelea paradisi celebensis (paradise tree snake)

Uncommon. Two individuals found in coconut plantations north of Labundo Bundo

Psammodynastes pulverulentus (mock viper)

Common and widespread throughout forest habitats. This was the most frequently encountered snake species.

Boiga irregularis (brown tree snake or cat snake)

Uncommon. Two individuals recorded in the cave on the road near Kaweli. One individual found crossing the road at night, on the forest edge west of Labundo Bundo.

Curora amboinensis (common freshwater turtle)

Uncommon. Several individuals observed in streams in the area. One individual trapped adjacent to a swamp in disturbed forest. One juvenile road-killed near a coastal swamp north of Labundo Bundo.

Bufo celebensis (Celebes toad)

Common and widespread throughout the region. Found in a wide range of aquatic and terrestrial habitats, including village surrounds and forest. Large breeding aggregations found along the river at the Primary Base Camp.

Oreophryne sp. (Undescribed species)

Uncommon. Several individuals found active at night in forest and several captured at pitfall trap sites. No calling activity during the survey period.

Uncommon. No calling activity during the survey period. One adult and one juvenile pit trapped in the Kakanawe Reserve.

Common in rice paddies and fields. Also found along the lower reaches of some streams near fields.

Aquatic/lotic species. Abundant along all flowing streams throughout the region. There are possibly two closely-related taxa present in the area and further work is required to resolve this.

Terrestrial species. Abundant along all streams throughout the region. Also associated with swamps, road drainage and rain pools in forested areas. Sub-adults also found throughout forested areas.

Arboreal Species. Abundant along all flowing streams throughout the region. Also found throughout forested habitats distant from streams. Small choruses found in coastal swamps in secondary forest north of Labundo Bundo.

Arboreal Species. Uncommon. Small breeding aggregations found along several streams in the area, and in coastal swamps in secondary forest north of Labundo Bundo.

Rhacophorus sp. (Undescribed species)

Arboreal Species. Common along all small flowing streams in the region.

Arboreal Species. Uncommon. Found around standing water bodies in the vicinity of Labundo Bundo and the Old Dutch House. Several individuals found in forested habitats and along water courses.

Polypedates sp.

Two individuals found near streams in forested habitats. Taxonomic identity unclear. Morphologically similar to P. leucomystax from which it may be distinguished by its shorter snout and the presence of dark spots on the flanks.

Numerous people assisted with various aspects of this survey. Operation Wallacea provided logistical and organisational support. Special thanks must go to Bonny Mochamad Stafei (the Bonster) for his companionship and logistical support. Many local people from Labundo Bundo provided assistance in the field. I am particularly indebted to Usman, Alamin and Laedi. Numerous Operation Wallacea volunteers also assisted with the work throughout the survey. I am also indebted to my fellow scientists, Tigga Kingston, Andy Jennings, James Burton and Phil Stannier, for their support and companionship.

Iskandar, D.T and Nio T.K. (1996). The amphibians and reptiles of Sulawesi, with notes on the distribution and chromosomal number of frogs. In: D.J. Kitchener and A. Suyanto (eds), Proceedings of the First International Conference on Eastern Indonesian-Australian Vertebrate Fauna, Manado, Indonesia. Pp. 39-46.

Bosch, H. A. J. (1985). Snakes of Sulawesi: Checklist, key and additional biogeographical remarks. Zoologische Verhandelingen. Uitgegeven door Het Rijksmueum van Natuurlijke Historie Te Leiden. No. 217.

Manthey, U. and Grossmann, W. (1997). Amphibien and Reptilien Sudostasiens. Natur & Tier-Verlag, Berlin.

Draco sp.

Gehyra sp.

Dendrelaphis p. pictus

Rhabdophis chrysargoides

Sinonatrix trianguligera

Ahaetulla p. prasina

Psammodynastes pulverulentus

Boiga irregularis (grey and orange forms)

Oreophryne sp.(undescribed new species)

Polypedates sp. (unresolved taxon)

Rhacophorus sp. (undescribed new species)

Cyrtodactylus sp.

Fejervarya cancrivora