Report on big-headed turtle, Platysternon megacephalum at lower Ing river, Chiang Rai Province, northern Thailand Big-headed turtle, Platysternon megacephalum, is a freshwater turtle species in Family Platysternidae and can be distinguished from other freshwater species by their distinctly characteristics such as massive triangular head which can not be retracted into its shell, upper and lower hooked beaks, flattened shell (both carapace and plastron) and a very long tail (Cha-ard et al., 2015; Cox et. al., 1998; Stuart et. al., 2001). This turtle species can be found in East and Southeast Asia, includes China, Vietnam, Laos, Myanmar, Cambodia and Thailand. In Thailand, this species was recorded from small rocky streams or creeks in montane forests atnorthern and northeastern Thailand. It was found hiddenunder crack or overhanging rocks during daytime and becomes active at night. Prey of this species are little known. Nevertheless, small freshwater invertebratesand fish were reported as a main diet (Cox et. al., 1998; Nuthaphand, 1979; Stuart et. al., 2001; Chan-ard et. al., 2015; Uetz, et. al., 2023). Moreover, Sung et al. (2016) reported that plant seeds were found in fecal samples of turtle from Hong Kong, China. According to IUCN red data list, this species is classified as a critically endangered species (CR) due to drastic population decline in natural habitat from habitat change and destruction, illegal poaching for traditional Chinese medicine, pet trade and others (IUCN, 2024; Pipatsawasdikul et. al., 2010; van Dijk and Palasuwan, 2000; Sung et. al., 2014). For CITES, this species was classified in to CITES appendix I (CITES 2023). In Thailand, this species is one of five endangered turtles and tortoises in Thailand and was a protected wildlife species by Thai law (Nabhitabhata and Chan-ard, 2005; Pipatsawasdikul et. al., 2010; Wildlife conservation office, 2024). Ing river is a tributary of Mekong River and one of the important water basins in northern Thailand, especially a lower part of the river, as known as lower Ing river. It was found that lower Ing river has important rows in a food resources, local economy and conservation on biodiversity (RECOFTC, 2024; Living River Siam Association, 2024). Many species of plants and animals were recorded across this area such as over 100 species of herbs, about 100 species of freshwater fish, 126 species of open area and water birds, at least 4 species of small mammals (2 otter species), at least 7 species of turtles, one species of tortoise, and more (Living River Siam Association, 2020; 2022; 2023). Many species of those organism are an important species due to global conservation status and Thai law (CITES, 2023; IUCN, 202 4; Wildlife conservation office, 2024). Fortunately, bigheaded turtles were also observed in upper stream at montane forest of this area. Therefore, aims of this study is to gain knowledges on the habitat and some biological aspects to provide data required for conservation and management decisions for this critically endangered and protected turtle species at lower Ing river. Data collection This study was conductedin the area of lower Ing river at2 districts included Khun Tan and Chiang Khong District, Chiang Rai Province, Thailand during June 2023 to January 2024. Data collection in this study was separated into 2 parts: habitat and morphology of turtle. UTM (WGS84) was used as datum for all coordinates in this study. Study sites
Five locations at lower Ing river, Chiang Rai Province, Thailand were selected for turtle survey. These locations were considered as study sites from previous records on big-headed turtle observations by local people (Figure 1). 1. Huai Sak at Yang Hom Subdistrict, Khun Tan District, Chiang Rai Province (47Q 636610N 2197354E) 491 m.asl. (Figure 2a) 2. Huai Dan Muang at Yang Hom Subdistrict, Khun Tan District, Chiang Rai Province (47Q 638611N 2208642E) 434 m.asl. (Figure 2b) 3. Huai Pha Lad at Huai So Subdistrict, Chiang Khong District, Chiang Rai Province (4 7 Q 628022N 2214975E) 369 m.asl. (Figure 2c) 4. Huai Pa Phlu at Huai So Subdistrict, Chiang Khong District, Chiang Rai Province (4 7Q 627284N 2216932E) 434 m.asl. (Figure 2d) 5. Huai So at Huai So Subdistrict, Chiang Khong District, Chiang Rai Province (4 7Q 627696N 2218809E) 429 m.asl. (Figure 2e) Figure 1: Five survey locations of big-headed turtle, Platysternon megacephalum, at lower Ing river, Huai so subdistrict, Chiang Khong District and Yang Hom Subdistrict, Khun Tan District Chiang Rai Province, Thailand (Google Earth). N 5 km Huai So Subdistrict Yang Hom Subdistrict
Figure 2: Five survey areas of big-headed turtle, Platysternon megacephalum, at lower Ing river, Chiang Rai Province, Thailand; Huai Sak at Yang Hom Subdistrict, Khun Tan District (2a), Huai Dan Muang at Sathan Subdistrict, Khun Tan District (2b), Huai Pha Lad at Huai So Subdistrict, Chiang Khong District (2c), Huai Pa Phlu at Huai So Subdistrict, Chiang Khong District (2d) and Huai So at Huai So Subdistrict, Chiang Khong District (2e). 2a 2b 2c 2d 2e
Habitat study Habitat of big-headed turtle on each observed location was investigatedusing samplingplot method. Three sampling plots (3x3 m) were placed in each observed location of this turtle. Center of first sampling plot was placed at exact turtle observed point. Other 2 sampling plots were placed at 50 meters in distance far upper and lower along the stream. These two sampling plots were chosen to represent unobserved point of turtle. Collected data from these 2 sampling plots were used to compare with data from first sampling plot (turtle observed point). For habitat data collection, each sampling plot (3x3 m) was divided into 9 subplots (1x1 m) which containing 100 grids (10x10 cm) inside and used to collect data on proportion of land and water surfaces, types of ground substrates and vegetation coverage on ground (Figure 3a). Data on coordinate, forest type and physical factors such as ambient temperature, water temperature and water qualities (water pH and water turbidity) were measured and recorded (Figure 3). Data on water qualities were measured using digital water quality tester (Figure 3d). Other notes on weather, area conditions and human activities were also recorded (Appendix I). Figure 3: Data collection on habitat of big-headed turtle, Platysternon megacephalum, at lower Ing river, Chiang Rai Province, Thailand; a 1x1 m subplot with 100 grids of 10x10 cm (3a) and data collection on turtle habitat (3b and 3c), physical factors such as water temperature and water qualities were measure using digital water quality tester (3d). Morphology 3a 3b 3c 3d
Study on morphological characters of big-headed turtle observed in this study was applied from Chan-ard et al. (2012) and Widiya et al. (2022) (Appendix II). Thirty-eight morphological characters of turtle were measured (millimeter, mm) and weighted (gram, g) using digital vernier caliper and digital handle spring balance to the nearest 0.1 mm and 0.5 g, respectively (Figure 4). Numbers of carapace and plastron scales were counted in 12 characters followed Nuthaphand (1979). Sex determination and completeness of shell were also evaluated. Turtle was released back into its natural habitat at observed location after measurement is completed. All data on morphological characters of this turtle were showed in Table 2. Figure 4: Morphological character measurements of big-headed turtle, Platysternon megacephalum, observed at lower Ing river, Chiang Rai Province, Thailand using digital vernier caliper and digital handle spring balance (4b and 4c). Turtle was kept in cloth bag during weighing (4a). Number of carapace, plastron and bridge scales were counted. Sex and shell condition were evaluated before released at the observed location (4d). Results According to 7 months of data collection period (June 2023 to January 2024), only single big-headed turtle was observed by local people at Huai Dan Muang, Yang Hom Subdistrict, Khun Tan District, 4a 4b 4c 4d
Chiang Rai Province (Figure 2b). Observed area is a rocky stream located in mixed deciduous forest with a small waterfall, pond, large overhanging rocks and steep banks (Figure 5). At the observed point (47Q 638915N 2208840E), this turtle was found resting on land over the boulder rock close to water surface during nighttime after sunset (after 18.00 pm, Figure 5c). On behavioral note, local villager said that this turtle just rested and stayed still on the rock. It faced toward to pond and ready to flee when be approached by him. Figure 5: Observed area of big-headed turtle, Platysternon megacephalum, at Huai Dan Muang, Yang Hom Subdistrict, Khun Tan District, Chiang Rai Province, Thailand (47Q 638915N 2208840E); a running rocky stream with large overhanging rocks and steep banks (5a), a small waterfall at observed area (5b) and the observed point of turtle (red circle) on a boulder rock close to water (5c). Habitat Data from 3 sampling plots (3 plots of 3x3 m; 27 subplots of 1x1 m; 900 grids of 10x10 cm) at turtle observation point were collected and calculated. Results showed that area with proportion of land and water surfaces at 80.33% and 19.67%, respectively, was chosen to be a terrestrial resting point of this turtle (47Q 638915N 2208840E) . Proportion of ground substrates on land were rocks (78.28%), gravels (1.38%), litters 5a 5b 5c
(18.81%) and soil (1.52%), whereas rocks was the only type of ground substrate (100%) under water surface in this sampling plot. For overall, proportion of ground substrates arranged from large to small were rocks (82.56%), litters (15.11%), soil (1.22%) and gravels (1.11%), respectively. Ambient temperature at this sampling plot was 25°C whereas water temperature was 23.9°C. About water qualities, pH at 7.07, electric conductivity at 201 µS/cm and 100 ppm of total dissolved solids were measured. Moreover, proportion of vegetation coverage on ground at this sampling plot was 5.33%. For an unobserved point at 50 meters far upper the stream (47Q 638926N 2208517E), this sampling plot showed the proportion of land and water surfaces at 79.89% and 20.11%, respectively. Proportion of ground substrates on land were rocks (31.02%), gravels (48.96%) and sand (20.03%). Proportion of ground substrates under water surface were rocks (87.29%) and gravels (12.71%). For overall, proportion of ground substrates arranged from large to small were rocks (42.33%), gravels (41.67%) and sand (16%), respectively. Ambient temperature at this sampling plot was 25°C whereas water temperature was 23.5°C. About water qualities, pH at 7.02, electric conductivity at 217µS/cm and 101ppm of total dissolved solids were measured. Moreover, proportion of vegetation coverage on ground at this sampling plot was 17.22%. For an unobserved point at 50 meters far lower the stream (47Q 638867N 2208570E), this sampling plot showed the proportion of land and water surfaces at 94.33% and 5.67%, respectively. Proportion of ground substrates on land were rocks (66.09%), litters (12.37%), soil (19.91%) and sand (0.82%). Proportion of ground substrates under water surface were rocks (9.80%) and soil (90.20%).For overall, proportion of ground substrates arranged from large to small were rocks (63.67%), soil (23.98%), litters (11.67%) and sand (0.78%), respectively. Ambient temperature at this sampling plot was 25°C whereas water temperature was 23.5°C. About water qualities, pH at 7.03, electric conductivity at 203 µS/cm and 110 ppm of total dissolved solids were measured. Moreover, proportion of vegetation coverage on ground at this sampling plot was 1.44%. Considered as a representative of unobserved points, these 2 sampling plots showed average proportion of land and water surfaces at 87.11% and 12.89%, respectively. Average proportion of ground substrates on land were rocks (87.89%), gravels (39.11%), litters (11.67%), soil (18.87%) and sand (16.78%). Average proportion of ground substrates under water surface were rocks (70.25%), gravels (9.91%) and soil (19.83%).For overall, these sampling plots showed average proportion of ground substrates ranged from large to small were rocks (53%), gravels (20.83%), soil (11.94%), sand (8.39%) and litter (5.83%), respectively. proportion of vegetation coverage on ground at this sampling plot was 9.33%. Different on water current at these 3 sampling plots was found by only running water surface of sampling plot at 50 meters far upper the stream (1 m/s) whereas other sampling plots had a still water surface. Data on habitat of observed turtle in this study were shown in Table 1.
Table 1: Proportion of land and water surfaces with percentage of ground plastysternon megacephalum, at Huai Dam Muang, Yang Hom Subdistrict, Khshown in italic bold font type). Physical factors and proportion of vegetation coSampling plots withcoordinates Temperature (°C) Water qualities Water flow (m/s) VcoAir Water pH Electric conductivity (µS/cm) Total dissloved solds (ppm) Ngam Muang (observed point of big-headed turtle) 47Q 638915N 2208840E 25 23.9 7.07 201 100 0 Ngam Muang (50 m far upper observed point) 47Q 638926N 2208517E 25 23.5 7.02 217 101 1 Ngam Muang (50 m far lower observed point) 47Q 638867N 2208570E 25 23.5 7.03 203 110 0 Unobserved point (Data were combined from both Ngam Muang 50 m far upper and lower observed points.) - - - - - -
substrates at observed and unobserved sampling plots of big-headed turtle, hun Tan District, Chiang Rai Province, Thailand (the highest percentage were verage on ground of each sampling plots were also shown. Vegetation coverage on ground (%) Surface types Proportion of surface types (%) Proportion of ground substrates Rocks Gravels Litters Soil Sand 5.33 Land 80.33 62.89 (78.28%) 1.11 (1.38%) 15.11 (18.81%) 1.22 (1.52%) 0.00 (0%) water 19.67 19.67 (100%) 0.00 (0%) 0.00 (0%) 0.00 (0%) 0.00 (0%) overall 100 82.56% 1.11% 15.11% 1.22% 0.00% 17.22 Land 79.89 24.78 (31.02%) 39.11 (48.96%) 0.00 (0%) 0.00 (0%) 16.00 (20.03%) water 20.11 17.56 (87.29%) 2.56 (12.71%) 0.00 (0%) 0.00 (0%) 0.00 (0%) overall 100 42.33% 41.67% 0.00% 0.00% 16.00% 1.44 Land 94.33 63.11 (66.90%) 0.00 (0%) 11.67 (13.37%) 18.78 (19.91%) 0.78 (0.82%) water 5.67 0.56 (9.80%) 0.00 (0%) 0.00 (0%) 5.11 (90.20%) 0.00 (0%) overall 100 63.67 0.00 11.67 23.89 0.78 9.33 Land 87.11 50.45% 22.45% 6.70% 10.78% 9.63% water 12.89 70.25% 9.91% 0.00% 19.83% 0.00% overall 100 53.00% 20.83% 5.83% 11.94% 8.39%
Morphology Twelve characters of shell and 38 morphological characters of big-headed turtle observed at Huai Dan Muang, Yang Hom Subdistrict, Khun Tan District, Chiang Rai Province were counted, measured and weighted. For scale count, one small nuchal scale, 5 neural scales, 8 costal scales (4 scales on each side), 22 marginal scales (11 scales on each side) and 2 supracaudal scales (one scale on each side) were counted from carapace.For gular, humeral, pectoral, abdominal, femoral and anal plates of plastron, two scales ofeach character (one scale on each side) were counted. Moreover, four scales on each left and right bridge were counted. Condition on shell of this turtle is completed and no damage was found. Fourteen morphological characters of shell, both carapace and plastron, were measured in this study. For carapace, carapace length (CL) was 136.3 mm, measured in a straight line from tip of nuchal scale to the end of supracaudal scale. Carapace widths were measuredfrom side to side of carapaceat 3 locations; front part between third marginal scales, middle partbetweensixth marginal scalesand rear partbetweenninth marginal scales. Front, middle and rear carapace widths (FCW, MCW and RCW) were 100.5, 108.3 and 111.6 mm, respectively. For plastron, plastron length (PL) was 110.5 mm, measured between tips of gular and anal plates. Like carapace width measurements, plastron widths were also measured at 3 locationsbut from side to side of plastron; front part between humeral plates, middle part between abdominal plates and rear part between femoral plates. Front, middle and rear plastron widths (FPW, MPW and RPW) were 53.8, 79.8 and 43.8 mm, respectively. Length and width of bridge scales were measured in total. Left bridge length (LBL) and width (LBW) were 35.6 and 8.3 mm, respectively. Right bridge length (RBL) and width (RBW) were 33.2 and 7.2 mm, respectively. Front and rare shell heights of were 48.9 and 44.8 mm, respectively. Front shell height (FSH) was measured from the highest tip of first neural scale of carapace to pectoral plate of plastron whereas rear shell height (RSH) was measured from the highest tip of forth neural scale to femoral plate of plastron. Eight morphological characters of appendages such as length of legs and feet were also measured. Front and rear feet lengths, both left and right, were measured from base of carpus or tarsus to tip of middle finger, claw excluded. Front left foot length (FLFL), front right foot length (FRFL), rear left foot length (RLFL) and rare right length (RRFL) were 23.7, 26.5, 31.2 and 30.7 mm, respectively. Forelimbs and hindlimb lengths, both left and right, were measured from base of carpus to elbow joint or base of tarsus to knee joint. Left forelimb length (LFL), right forelimb length (RFL), left hindlimb length (LHL) and right hindlimb length (RHL) were 37.8, 39.5, 40.5 and 38.2 mm, respectively. Tail length (TL) was 175.0 mm which measured from the opening of the cloaca to tip of tail. Tail height (TH) of 15.4 mm and tail width (TW) of 19.1 mm were measured at tail base close to the opening of the cloaca. Twelve morphological characters of turtle head were also measured. Head length (HL), width (HW) and height (HH) were 52.7, 45.5 and 30.2 mm, respectively. Length (EL) and width (EW) of both eyes were 11.6 and 10.8 mm, respectively. Length between eyes (LE) was 17.5 mm. Skull height (SH) was 22.9 mm and snout length (SL) was 11.6 mm. Moreover, length and height of turtle beaks were also measured. Upper beak height (UBH), upper beak length (UBL), lower beak height (LBH) and lower beak length (LBL) were 14.9, 38.5, 19.9 and 37.5
Table 2: Morphological characters of big-headed turtle, Platysternon megacephChiang Rai Province, Thailand. Thirty-eight morphological characters were meaNumbers of scales of 12 characters of carapace and plastron were counted. Morphological characters Size Morphological charaCARAPACE (mm) APPENDAGCarapace Length, CL 136.3 Left Forelimb Length, LFL Front Carapace Width, FCW 100.5 Front Left Foot Length, FLFL Middle Carapace Width, MCW 108.3 Left Hindlimb Length, LHL Rear Carapace Width, RCW 111.6 Rear Left Foot Length, RLFL Right Forelimb Length, RFL PLASTRON (mm) Front Right Foot Length, FRFPlastron Length, PL 110.5 Right Hindlimb Length, RHL Front Plastron Width, FPW 53.8 Rear Right Foot Length, RRFMiddle Plastron Width, MPW 79.8 Rear Plastron Width, RPW 43.8 HEAD Head Length, HL BRIDGE (mm) Head Width, HW Left Bridge Width, LBW 8.3 Head Hight, HH Left Bridge Length, LBL 25.6 Right Bridge Width, RBW 7.2 Skull Hight, SH Right Bridge Length, RBL 33.2 Snout Length, SL Length Between Eyes, LE SHELL HEIGTH (mm) Eye Length, EL Front Shell Height, FSH 48.9 Eye Width, EW Rear Shell Height, RSH 44.8 Upper Beak Height, UBH TAIL (mm) Upper Beak Length, UBL Tail Length, TL 175.0 Lower Beak Height, LBH Tail Height, TH 15.4 Lower Beak Length, LBL Tail Width, TW 19.1 WEIGHBody Weight, W
halum, observed at Huai Dan Muang, Yang Hom Subdistrict, Khun Tan District, asured and weighed to the nearest 0.1 mm and 0.5 gram, respectively. acters Size Number of scales GEs (mm) CARAPACE 37.80 Nuchal scale 1 23.70 Costal scales (on each side) 4 40.50 Marginal scales (on each side) 11 31.20 Supracaudal scales (on each side) 2 39.20 FL 26.50 PLASTRON 38.20 Gular plates (on each side) 1 FL 30.70 Humeral plates (on each side) 1 Pectoral plates (on each side) 1 (mm) Abdominal plates (on each side) 1 52.7 Femoral plates (on each side) 1 45.5 Anal plates (on each side) 1 30.2 BRIDGE 22.9 Left bridge scales 4 11.6 Right bridge scales 4 17.5 11.6 10.8 14.90 38.50 19.90 37.50 HT (g) 460.0
mm, respectively. Beak length, both upper and lower jaws, was measured from tip to end of beak scale whereas beak height was measured at the highest point of beak. Weight of this turtle was 460.0 gram. Digital balance was tared to zero by container (a cloth bag) before weighing. All measurement on morphological characters of this turtle in this study were shown in Table 2. Conclusions and discussions Habitat Most study on big-head turtle, Platysternon megacephalum, reported that this turtle species spend their lifetime at stream in montane forest area and usually active at nighttime (Chan-ard et al., 2012; Pipatsawasdikul et al., 2010; Shen et al., 2010; Sung et al., 2015a). Despite only one turtle was observed here at Huai Dan Muang, Yang Hom Subdistrict, Khun Tan District, Chiang Rai Province, it was observed in the area of upper rocky stream in mixed deciduous forest, consists of numbers of large overhanging rocks, small stream, deep pond and caves. The highest proportion of ground substrates at observed sampling plot was rocks (82.56%) with much lower proportion of other substrates (1.11% of gravels, 15.11% of litters and 1.22% of soil). Data from unobserved sampling plots also showed the high proportion of rock substrate (53.0%) but proportion of other substrate types were much higher than the observed sampling plot (20.83% of gravels, 5.83% of litters, 11.94% of soil and 8.39% of sand). Average percentage of vegetation coverage on ground at unobserved sampling plots were also higher than the observed sampling plot at 9.33% and 5.33%, respectively. Previous studies on habitat of this freshwater turtle species showed that big-headed turtles in China preferred to stay in a pool habitat with rocky substrates, caves with low percentage of vegetation coverage rather than other in-stream or terrestrial habitats (Shen et al., 2010; Sung et al., 2015a; Xiao et al., 2023). Habitat selection of this turtle species was also supported by study on distribution of this turtle species in Thailand by Pipatsawasdikul et al. (2010). These could be explainedthe undetected situation at unobserved sampling plots (Figure 6). Area condition at 50 meters far upper the steam sampling plot was a small flat area with shallowed running stream (1 m/s). Percentage of ground substrates at this sampling plot consists of 16.0% of sand with rocks and gravels in quite similar proportion(42.33% and 41.77%, respectively) with slightly high percentage of vegetation coverage on ground (17.22%). Another sampling plot, area condition at 50 meters far lower the steam sampling plot wasa small waterfall with still water surface of artificial check dam. This situation affected a turbidity of water and ground substrates at this sampling plot by increased turbidity to be the highest (110 ppm) and increased the proportion of soil substrate (23.89%) caused by sedimentation among other sampling plots. Construction materials of this check dam were also left inside and along the stream area. Thus, all of these situations could affect the appearance of big-headed turtle in these sampling sites. Besides, data on physical factors such air temperature, water temperature and water qualitiesbetween sampling plots were slightly different. However, this difference could not be statistically confirmed due to number of sample sizes were too low.
Figure 6: Area condition at unobserved sampling plots at Huai Dan Muang, Yang Hom Subdistrict, Khun Tan District, Chiang Rai Province, Thailand; 50 meters far upper the stream sampling plots (6a) and 50 meters far lower the stream sampling plot (6b). 6a 6b
Nevertheless, resting on terrestrial habitat that observed in this study was an unusual behavior of this turtle species. Shen et al. (2010) and Sung et al. (2015a) reported that this turtle preferred to spend most of their time under water surface or remain hidden in its refugia. Morphology For most of turtle species, males are distinctly differentiating from females by their plastron shape. Concave or intended to this shape of plastron is one of male sexual characters. However, the flatten shell of both males and females caused indistinctive shape of plastron between sexes for this species. Thus, other morphological characters were used for sex determination. Xiao et al. (2021 and 2023) reported that turtle with the opening of the cloaca extends beyond the posterior margin of the supracaudalscales will be identified as male. Sung et al. (2013) reported that males had a longer precloacal tail length and a thicker tail than females. About age determination, the count of growth rings was not suggested to applied for this turtle species by Sung et al. (2015b) due to an inaccuracy and unreliability of this method. They suggested to use growth curves of the von Bertalanffy and logistic growth model in their research. The average age of maturation of male was 13 years old or average carapace length at maturation was 130 mm. Xiao et al. (2023) also suggested that turtle with carapace length greater than 100 mm is an adult for both sexes. According to this information, turtle observed in this study was an adult male with more than 10 years old (probably about 15 years old according to those models). Other turtle species Not only one big-headed turtle, Platysternon megacephalum, was founded, other 7 species of turtles and tortoise were observed by local villagers in this study area throughout study period (Table 3). Five native and two exotic species were recorded. Four adults of elongated tortoise, Indotestudo elongata, were found in forest areas both at Chiang Khong and Khun Than Districts. Five Oldham's leaf turtles, Cyclemys oldhamii, were found in forest streams at Huai So Subdistrict, Chiang Khong District (three adults and two juveniles). Single adult of Southeast Asian box turtle, Cuora amboinensis, three Malayan snail-eating turtles, Malayemys macrocephala(two adults and one juvenile), and one adult of Southeast Asian softshell turtle, Amyda ornata, were found around the village and wetland areas at Huai So Subdistrict, Chiang Khong District. IUCN (2024) evaluated conservation status of these species; (CR) for elongated tortoise, Indotestudo elongata, Endangered (EN) for Oldham's leaf turtles, Cyclemys oldhamii and Southeast Asian box turtle, Cuora amboinensis, Vulnerable (VU) for Asian softshell turtle, Amyda cartilaginea(previous scientific name of A. ornate dispersedin this area), and Least concern (LC) for Malayan snaileating turtles, Malayemys macrocephala. For CITES (2023), all native species in this study were classified into CITES appendix II. Likewise, all of these turtle species were protected by Thai law. This information showed the important of this area for being a turtle diversity hotspot and/or being a biodiversity reservoir of turtles and tortoise in this region. About exotic species, Chinese softshell turtle, Pelodiscus sinensis, and red-eared slider, Trachemys scripta, were recorded by local fishermen during setting their fish traps. One of each species were found in tributary of Ing river and inside main Ing river, respectively. These species were classified as invasive species of Thailand, (Zungsontiporn et al., 2020).
Conservation aspects Illegal poaching is the major factor of population reduction of big-headed turtle across their geographic distribution (Pipatsawasdikul et al., 2010; Sung et al., 2015; Xiao et al., 2023). Therefore, urgent actions on conservation and management are needed. Study on their habitat is one of the acquisitions on basic knowledge that could be benefit to its conservation. Xiao et al. (2023) suggested that protecting microhabitats and food sources is an important for survival and reproduction of this turtle species. Hence, protecting rocky stream with small waterfall, pond, overhanging rocks and caves, with low vegetation coverage on ground, upper in the montane forest is extremely necessary for conservation of this turtle species in this area. Effects from human activities in this area are another concern for turtle conservation. Changes of habitat such as area conditions and water qualities from check dam construction and collecting of non-timber forest products (NTFPs), especially small invertebrates for food supply, are directly affected to turtle surveillance. Xiao et al. (2023) and Sung et al. (2016) also reported that this turtle species both adults and juveniles, as well as males and females, preferred habitat with high diversity and availability of food resources, especially small invertebrates. Unfortunately, there was no evidence on diet of this turtle species occurred throughout this study period. Nevertheless, numbers of small invertebrates such as small freshwater crabs and shrimps were encounteredacross the observed streams during study period. Moreover, Sung et al. (2015) suggest that innovative methods may be needed to tackle illegal turtle trapping such as an infrared-triggered cameras equipped with remote viewing or recorder. Reintroduction program of this turtle species could be possibly successful in this study area due to conservation perspective and strangeness of local communities. However, more knowledge on biology, ecology, habitat, home range and much more on big-headed turtle life should be conducted for more precisely conservation and management plans. Together with traditional methods such as increasing patrol efforts, reducing and restricting human activity areas, could improve the effectiveness of the conservation not only for big-headed turtles but for other organism in lower Ing river area.
Table 3: Other species of turtles and tortoise, both native and exotic specieconservation statuses were also shown). Common name Scientific name Coordinate (UTM: WGS 84) Native species Family Testudinidae Elongated tortoise (4 individuals) Indotestudo elongata 47Q 638770N 2208588E Adult, Fo47Q 645167N 2224719E Adult, We47Q 627205N 2216049E Adult, UpChiang K47Q 627230N 2215842E Adult, RuChiang KFamily Geoemydidae Oldham's leaf turtle (4 individuals) Cyclemys oldhamii 47Q 628480N 2217188E Juvenile, at Huai S47Q 627873N 2214852E Adult, TrSubdistric47Q 627873N 2214852E Adult, sam47Q 630762N 2212926E Adult, a sSubdistric47Q 628205N 2117717E Juvenile, SubdistricSoutheast Asian box turtle Cuora amboinensis 47Q 638840N 2213542E Adult, WChaing KMalayan snail-eating turtle (3 individuals) Malayemys macrocephala 47Q 633636N 2214154E Juvenile, Subdistric47Q 631609N 2213440E Adult, LaChiang K47Q 637354N 2213822E Adult, BuKhong DFamily Trionychidae Asian softshell turtle Amyda cartilaginea 47Q 629378E 2214687N Adult, HuChiang K
s, observed at lower Ing river, Chiang Rai Province, Thailand (locations and Location Conservation status Details IUCN* (wild population) CITES Thai law** orest area at Yang Hom Subdistrict, Khun Tan District CR Appendix II P etland forest at Chiang Khong District pper forest area at Huai So Subdistrict, Khong District ubber plantation near forest area at Huai So Subdistrict, Khong District Small check dam in rubber plantation close to forest area So Subdistrict, Chiang Khong District EN Appendix II P ributary of Huai So stream in forest area at Huai So ct, Chiang Khong District me location with previous turtle small tributary of Huai So stream in forest area at Huai So ct, Chiang Khong District In the middle of Huai So stream in forest area at Huai So ct, Chiang Khong District Wetland near Pa Or temple at Bun Rueang Subdistrict, Khong District EN Appendix II P Small drainage canal in rice field area at Huai So ct, Chiang Khong District LC Appendix II P arge drainage canal in rice filed at Huai So Subdistrict, Khong District un Rueang wetland, Bun Rueang Subdistrict, Chaing istrict uai So water reservoir at Huai So Subdistrict, Khong District VU Appendix II P * IUCN conservation status: Critically endangered (CR) ** Thai law: Protected species (P) Endangered (EN) Non-protected species (NP) Vulnerable (VU) Least concern (LC)
Table 3 (cont.): Other species of turtles and tortoise, both native and exoticconservation statuses were also shown). Common name Scientific name Coordinate (UTM: WGS 84) Exoticspecies Family Trionychidae Chinese softshell turtle Pelodiscus sinensis 47Q 632494N 2213732E Adult, TrSubdistricFamily Emydidae Red-eared slider Trachemys scripta 47Q 636916N 2213634E Adult, UnHuai So S
c species, observed at lower Ing river, Chiang Rai Province (locations and Location Conservation status Details IUCN (wild population) CITES Thai law ributary of Huai So stream in forest area at Huai So ct, Chiang Khong District VU - NP nder the bridge at main Ing river between Bun Rueang and Subdistricts, Chaing Khong District LC - NP * IUCN conservation status: Critically endangered (CR) ** Thai law: Protected species (P) Endangered (EN) Non-protected species (NP) Vulnerable (VU) Least concern (LC)
References Chan-ard, T., Cota, M., Achachak, C. and Safuwong, M. 2012. Measurements of the big-headed turtle (Platysternon megacephalum Gray, 1831) (Platysternidae, Testudines) from Phu Luang, Loei Province, northeastern Thailand. The Thailand Natural History Museum Journal. 6(2): 153-157. Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). 2023. Appendices I, II and III. From https://cites.org/eng/app/appendices.php (20 January 2024). Cox, M.J., van Dijk, P.P., Nabhitabatha, J. and Thirakhupt, K. 1998. Snakes and Other Reptiles of Thailand and South-East Asia. Asia Book, Bangkok. The IUCN Red List of Threatened Species (IUCN). 2024. Red List of Threatened Species. Version 2023-1; Big-headed turtle, Platysternon megacephalum. From https://www.iucnredlist.org/species/17585 /1423706 (20 January 2024). Living River Siam Association. 2020. Report on species of herbs and edible plants in Thung Ngew wetland. From https://www.livingriversiam.org/images/ing-report/2563-07_Ban_Thung_Ngew_Wet_Forest_Plant _Research_Report.pdf (20 January 2024). Living River Siam Association. 2022. Otters in lower Ing river (in Thai). From https://anyflip.com/txktg /qita/?fbclid=IwAR2foB9dZiZ9o0EfrXf85Z-uRqicfttcXgj-QU9jjMGQUg1SCEYtDl2FiiM (20 January 2024). Living River Siam Association. 2023. Field guide to water birds in lower Ing river ecosystem (in Thai). From https://anyflip.com/txktg/wfnu/?fbclid=IwAR0Li2lPcVtcNvomDpt6VkhH9yUZB3zioTXZ2teOFagaFsN72Q0IA jc0qw (20 January 2024). Living River Siam Association. 2024. Ing river.From https://www.livingriversiam.org/thai-river/ing (20 January 2024) Nuthaphand, W. 1979. The turtles ofThailand, 1sted. Mitbhadung Press, Bangkok. Pipatsawasdikul, K., Voris, H.K. and Thirakhupt, K. 2010. Distribution of the big-headed turtle (Platysternon megacephalum, Gray 1831) in Thailand. Zoological Studies. 49(5): 640-650. Regional Community Forestry Training Center for Asia and the Pacific (RECOFTC). 2024. Ing watershed. From https://www.recoftc.org/en/thailand/projects/ing (20 January 2024). Shen, J., Pike, D. and Du, W. 2010. Movements and microhabitat use of translocated big-headed turtles (Platysternon megacephalum) in southern China. Chelonian Conservation and Biology. 9(2): 154-161.
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Appendix I
Data sheet for physical factors recoded from 3 sampling plots in this study (turtle observed point, 50 meters far upper and 50 meters far lower the stream of turtle observed points). Data sheet for ground surface types, types of ground substrates and vegetation coverage on ground recorded from 9 subplots of 3 sampling plots in this study (turtle observed point, 50 meters far upper and 50 meters far lower the stream of turtle observed points). Sampling plot No: Subplot no: Date: Picture numberof thissubplot: Time: Location: Water surface: runningwater, still water or no Ground substrates: Rocks, Gravels, Soil, Sandoretc. and Vegetation coverage: Yes/No
Appendix II Data sheet for morphological character measurement of observed turtle
Appendix III a b c f d e g
Sample pictures of other 7 turtle and tortoise species recorded from lower Ing river, Khun Tan and Chiang Khong District, Chiang Rai Province, Thailand (photo courtesy of Living River Siam Association); native species such as elongated tortoise, Indotestudo elongata (a), Oldham's leaf turtles, Cyclemys oldhamii (b), Southeast Asian box turtle, Cuora amboinensis (C), Malayan snail-eating turtles, Malayemys macrocephala (d) and Southeast Asian softshell turtle, Amyda ornate (e), and exotice species such as Chinese softshell turtle, Pelodiscus sinensis (f) and red-eared slider, Trachemys script (g).