Notes on Exploitation, Population Status, Distribution, and Natural History of the Sulawesi Forest Turtle (Leucocephalon yuwonoi) in North-Central Sulawesi, Indonesia
ABSTRACT
A field survey of the Sulawesi forest turtle (Leucocephalon yuwonoi) in north-central Sulawesi demonstrates that the species is collected by turtle hunters, and population densities are relatively low. Several new localities for the species and data on reproduction, habitat, and parasites are reported in this article.
There are about 300 extant species of turtle in the world; 39 occur in Indonesia (Iskandar 2000), and 18 of these are exported live to commercial overseas markets (Yuwono 1998). In the past several years, demand for turtles from Indonesia has been increasing, especially in China, Europe, and the United States (Suwelo 1999; Iskandar 2000; Samedi and Iskandar 2000).
The Sulawesi forest turtle (Leucocephalon yuwonoi) is one of the most poorly researched turtles in the world. It was first described in 1995 as endemic to a small area on the Minahassa Peninsula of Sulawesi (McCord et al. 1995; Platt et al. 2001). Within a year of discovery, it began to appear in markets in mainland China. The species, which does not usually thrive in captivity, may soon become extinct (Lovich et al. 2001). Almost nothing is known concerning the ecology of L. yuwonoi in the wild (Platt et al. 2001). L. yuwonoi is currently classified as Critically Endangered by the International Union for the Conservation of Nature (2004).
The aim of this field survey was to assess the current exploitation level, population status, natural history, and distribution of L. yuwonoi in the north-central part of Sulawesi.
Methods
Fieldwork was conducted from 28 April to 13 May 2002 in 5 subdistricts in north-central Sulawesi. Localities were chosen based on exporter information from Jakarta. I interviewed turtle hunters, local buyers, and 1 supplier in Palu, and examined their captive specimens. I gathered natural population data by walking along small creeks at night or early morning, following the hunters as transect lines. Transects were located along small creeks at the following localities: (1) Ganonggol River, Desa Village, Karya Agung, Moutong Subdistrict, Parigi-Moutong District (0°31′5.34″N; 121°02′6.93″E; elevation 69 m); (2) Kuala Besar River, Labonu Village, Dondo Subdistrict, Toli-Toli District (0°40′2.18″N; 120°39′4″E; elevation 174 m); (3) Bangkir River, Bangkir Village, Dampal Selatan (Damsel) Subdistrict, Toli-Toli District (0°15′8.27″N; 120°39′4.07″E; elevation 25 m); (4) Kuala River, Tibo Village, Sindue Subdistrict, Donggala District (0°29′5.03″S, 119°47′5.19″E; elevation 96 m); and (5) Kuala River, Toaya Village, Sindue Subdistrict, Donggala District (0°35′7.54″S; 119°49′8.23″E; elevation 48 m) (Fig. 1). The following data were collected along each transect: man-hours of collecting turtles; straight carapace length (CL), carapace width (CW), and mass of each turtle captured; and total number of turtle hunters in the area.
Citation: Chelonian Conservation and Biology 5, 2; 10.2744/1071-8443(2006)5[320:NOEPSD]2.0.CO;2
I also collected nematodes from the feces of 5 dissected dead turtles from captives (2 females and 2 males from Labonu and 1 female from Karya Agung). Nematodes were preserved in ethanol and examined using SEM type JSM-5310 LV. Reproductive data was gathered by dissecting dead female turtles.
Results and Discussion
Six turtle collectors from the 5 subdistricts surveyed were interviewed (Table 1). These collectors received turtles from turtle hunters and farmers in their area and also hunted turtles themselves. All worked on farms or plantations and collected turtles for supplementary income. In each subdistrict, the average number of turtle collectors was 1.2 (range 1–2) and the average number of turtles caught in 11 months was 26.4 (132/5), with the average collecting time for turtles on hand as 2.2 months (range 1.5–4). During 1 month, the mean number of turtles caught per collector was 12.0 (26.4/2.2). Based on these results, the total estimated number of turtles collected in 2002 from this part of Sulawesi was 720.
This amount suggests that L. yuwonoi is already relatively depleted locally, because the species has a limited distribution and prefers specialized habitats such as small draining rivers near the secondary forest and small canals draining the cacao plantations. These habitats are diminishing due to disturbance from human activity.
McCord et al. (1995) reported that adult males have CL at least 25.6 cm and adult females at least 22.1 cm; Platt et al. (2001) reported 2 adult males from Cape Santigi with CL of 23.7 and 23.0 cm. Reproductive data from 3 dissected females collected in Moutong, Sindue, and Bangkir demonstrated that females were sexually mature at 18.4 cm CL (Table 2). These data corroborate the findings of Innis (2003) that female L. yuwonoi lay only 1 or 2 eggs per clutch and are sexually mature already at 17.5 cm CL.
With respect to population densities and catch-per-unit effort, the Bangkir population was the highest (Table 3), probably due to a relatively well-preserved population from less overexploitation there. The low population densities in Labonu and Karya Agung may have resulted from intensive collecting activity and anthropogenic habitat disturbance, probably due to easy access from Palu city. Habitat disturbances in Labonu and Karya Agung from herbicides used in farms and by logging activity also seem to have caused a decline of turtle populations in these localities.
All localities recorded in this study, except Ganonggol River (Karya Agung), were new distributional records for L. yuwonoi. The species was previously only known from a few localities in northern Sulawesi: “near Gorontalo” (0°33′N; 123°05′E), “near Poso” (1°23′S; 120°45′E) (McCord et al. 1995), and “Konggol River” (0°35′N; 120°54′E) (Platt et al. 2001). The creek of Ganonggol River surveyed in Karya Agung in this study is probably from same river as surveyed by Platt et al. (2001), but they called it the Konggol River.
The habitat of the creek at Gononggol River was a rocky channel with abundant woody debris draining an area of secondary growth forest. The creeks at Tibo and Toaya had relatively similar habitats. All turtles caught in Bangkir were from modified habitats, including small marshes and drainage streams in cacao or coconut plantation areas (Fig. 2). The substrate in these habitats in Bangkir was generally sand, mud or occasionally rocky with vegetation consisting of grasses: Colocasia esculenta, Selaginella plana, Derris elliptica, Alocasia macrorhiza, Diplazium esculentum, and Vitis trifolia.
Citation: Chelonian Conservation and Biology 5, 2; 10.2744/1071-8443(2006)5[320:NOEPSD]2.0.CO;2
This study also proved that the Labonu population has been infected by the nematode Falcaustra kutcheri (Fig. 3), recently described by Bursey et al. (2000).
Citation: Chelonian Conservation and Biology 5, 2; 10.2744/1071-8443(2006)5[320:NOEPSD]2.0.CO;2
I strongly recommend that the Indonesian government offer protection to L. yuwonoi because it is an endemic species with a highly limited geographic distribution and is seriously threatened by habitat destruction and overexploitation due to the live animal trade. Moreover, L. yuwonoi has an extremely low reproductive rate with only 1 or 2 eggs per clutch, and it is difficult to maintain and breed in captivity.
Map of north-central Sulawesi, showing surveyed localities (closed circles) of Leucocephalon yuwonoi. Open stars indicate localities from McCord et al. (1995), and closed star indicates the locality from Platt et al. (2001).
Bangkir, north-central Sulawesi: a small marsh behind a small stream on a cacao and coconut plantation area, where an adult female (lower photo) was found.
The morphology of Faulcaustra kutcheri nematode by SEM, magnification 350×. (Photo by E. Purwaningsih).
