| Citation |
Stuart, B., Sumontha, M., Cota, M., Panitvong, N., Nguyen, T.Q., Chan-Ard, T., Neang, T., Rao, D.-q. & Yang, J. 2019. Physignathus cocincinus. The IUCN Red List of Threatened Species 2019: e.T104677699A104677832. https://dx.doi.org/10.2305/IUCN.UK.2019-2.RLTS.T104677699A104677832.en. Downloaded on 04 August 2020. |
Description |
JUSTIFICATION
Listed as Vulnerable on the basis that this species, while widespread, is subject to high rates of harvesting throughout most of its range. Harvesting takes place principally at a subsistence level for food, but the species is also heavily-exploited, especially in Viet Nam, for export to support the European pet trade; combined, this harvest targets animals at all life stages. Additionally, this species is a specialist in closed-canopy, lowland riparian forest, a habitat at particular risk from habitat conversion as well as one highly accessible to collectors. Rates of decline in Viet Nam were estimated at 20% in 10 years in 2007 (equating to a decline of more than 30% over a three generation period estimated at 18 years based on a generation length of six years) and there is no reason to expect that these have decreased; elsewhere there are localized reports of declines as great as 50% over a three generation period. The species occurs in protected areas throughout its range, but it is likely to be relatively secure only in Thailand, which represents its western range margin. Consequently rates of decline across the species range as a whole are suspected to exceed 30% over the past three generations (with the caveat that this is a precautionary estimate and further research is needed to confirm this rate of decline), and the causes of decline are not reversible and have not ceased, nor are they likely to in the forseeable future. Due to the species restricted distribution (with an area of occupancy thought to be below 500 km2), the species is thought likely to warrant a local listing of Endangered.
RANGE DESCRIPTION
This species occurs throughout Lao PDR, Cambodia and Viet Nam in appropriate habitat. It has been found throughout eastern Thailand from the Eastern Forest Complex south to the coast, but only in protected areas (M. Cota pers. comm. 2017), and is found in southern China, in the southwest part of Guangdong, Guangxi, and Hekou in Yunnan. It is believed to have an area of occupancy below 500 km in China. It has been introduced to Taiwan (G. Norval, cited in Uetz 2017). It has been found from sea level up to 700 m asl (Stuart et al. 2006); Nguyen et al. (2018) report the species presence in a section of stream with a maximum elevation of 770 m asl.
DESCRIPTION
This species is locally abundant, although it is subject to ongoing declines as a result of harvesting of both adults and eggs for food, and juveniles for the international pet trade, as well as declines in habitat quality in parts of the range. In at least one site in Cambodia the species has undergone an apparent decline of up 50% in 18 years (representing an estimated three generations, applying a generation length estimate of six years), based in part on interviews with local hunters who record that it is becoming harder to find for food (T. Neang, unpublished data). Fieldwork since 2015 in central Viet Nam suggests the population here is dominated by juveniles, implying that animals may not be surviving to adulthood in large numbers (Q.T. Nguyen pers. comm. 2017). The species was listed as Vulnerable in the 2007 Viet Nam Red Book 2007 on the basis of an expert-estimated population reduction of 20% over 10 years across the country as a whole, although it remains locally common in forested areas along streams in Viet Nam (Q.T. Nguyen pers. comm. 2017). The first population-level mark-recapture survey of this species, across 14 stream transects in Thua Thien Hue Province in 2016 and 2017, found that the population appeared stable in two of three districts in this province over this short period but that the population size in this area may have been as low as 232-250 individuals in 2017 (Nguyen et al. 2018). A "distinct decline" in the number of individuals encountered was observed over the period between April and June 2017 in the third district, and no mature individuals were recorded in the June survey (Nguyen et al. 2018). It is considered to be a rare species in China, with limited data about its population.
HABITAT AND ECOLOGY
This species inhabits evergreen forest, where it is always found in association with streams and rivers. Animals are sedentary and exhibit strong site philopatry: Nguyen et al. (2018) found that capturing and releasing animals as part of a mark-recapture study did not cause them to abandon favoured perch sites. Nguyen et al. (2018) found that the species was consistently less abundant at higher elevations in all survey sites, and hypothesized that this may relate to stream properties and water quality. It rests on the branches of trees overhanging the waterway, into which it will plunge to escape danger. It forages in the middle of the day for insects, earthworms, and small rodents. Clutches comprise 8 to 12 eggs laid in exposed sandy areas on streambeds. It roosts overnight high up in streamside trees (Chan-ard et al. 2015). Although long-lived the species is relatively fast-growing, with juveniles reaching subadult size within two months (Nguyen et al. 2018). This species inhabits tropical areas of China at around 100 m asl. Zhao et al. (1999) reported that the it is commonly found in forest and rocky streams. It lays about 6–14 eggs per clutch (Zhao et al. 1999).
THREATS
Harvesting of this easily-captured species - primarily for food, but also for the international pet trade - constitute serious threats. A local threat assessment of this species was reported by Nguyen et al. (2018) found that this species was under harvesting pressure in all surveyed districts of Thua Thien Province, based on interviews with hunters and evidence of local trade and consumption. The species is restricted to low-elevation closed-canopy forests along water courses, which facilitates access to its habitat both for collectors and for habitat modification and degradation. Adults and eggs are harvested for food, while juveniles are taken for the pet trade (B. Stuart pers. comm. 2017). Interviews with hunters in Thua Thien Province indicate that larger males are favoured for harvesting, and a female-skewed sex ratio observed in targeted stream surveys in 2016 and 2017 maybe an indicator population-level impacts of harvest (Nguyen et al. 2018). Animals are still readily obtained in this area, and there have been no efforts to captive-breed the species for food as a result (Nguyen et al. 2018). Cambodia and Laos in particular habitat loss is extensive as a result of agriculture and development, as well as in Lao PDR (T. Neang and B. Stuart pers. comm. 2017). Timber extraction, agriculture, urban development, and road construction that divides the habitat and further increases exposure to hunting (including hunting within nature reserves - Nguyen et al. 2018) all represent serious pressures, and fragment the habitat of this stream-dependent, sedentary species (Nguyen et al. 2018). In China this species is threatened by pet trade, and habitat loss due to urban development, hydropower development, and tourism (D.Q. Rao pers. comm. 2018).
USE AND TRADE
This species is harvested for food throughout most of its range, with both adults and eggs taken. It has been recorded in the domestic pet trade in Viet Nam (Nguyen et al. 2018). It is extremely common in the international pet trade, especially in Europe, and while the species is very widely captive-bred juveniles are taken from the wild for export, especially from Viet Nam. The CITES Trade Database reports 44,741 animals exported from Viet Nam (over 43,000), Thailand and Indonesia (the origin of the 162 animals exported from Indonesia, where the species does not occur, is not reported) into European Union countries between 2010 and 2016; in every year but 2010 and 2015 annual exports exceeded 8,200. Imports show a slight declining trend over this period, but a longer time series will be necessary to determine whether this is significant. The vast majority of these were live animals presumably intended for the pet trade, but the records include over 2,000 animals imported as skins or leather products. In China, it used to be popular in the domestic pet trade, as well as for food and traditional medicine, but is difficult to collect due to its rarity.
CONSERVATION ACTIONS
This species occurs in multiple protected areas in all range states; the species distribution in Thailand is essentially completely protected, but this represents a minority of the distribution. An assessment of its population status, abundance and distribution is recommended (Nguyen et al. 2018). Captive breeding for local use should be considered (Nguyen et al. 2018); this species breeds very readily in captivity in the international pet trade. Conservation measures that limit harvest and trade within range countries are needed. An evaluation of the scale, volume and impacts of trade are urgently needed to evaluate whether this species is a candidate for international control measures. Review of this species by CITES is recommended (B.L. Stuart pers. comm. 2017), as the species is not CITES listed. It is listed in the "List of Beneficial or of Important Economic or Scientific Value Terrestrial Wild Animals under States Protection", under the protection of the "Law of the Peoples Republic of China on the Protection of Wildlife" (L. Shi and B. Cai pers. comm. 2018). |
