| Citation |
Choudhury, B.C., Cota, M., McCormack, T., Platt, K., Das, I., Ahmed, M.F., Timmins, R.J., Rahman, S. & Singh, S. 2019. Manouria emys (errata version published in 2019). The IUCN Red List of Threatened Species 2019: e.T12774A152052098. https://dx.doi.org/10.2305/IUCN.UK.2019-1.RLTS.T12774A152052098.en. Downloaded on 12 February 2020. |
Description |
JUSTIFICATION
Manouria emys is in severe decline. Based on habitat loss rates alone, half the area of suitable lowland and mid-elevation evergreen forest has been degraded and lost in the past half century throughout its range. In addition, the species has suffered long-term subsistence collection and intensive commercial exploitation for East Asian consumption trade in recent years. Overall, the species has declined by at least 80% in the past three generations (135 years). This decline is expected to continue as turtle exploitation through most of its range remains beyond effective control, subsistence collection and poaching occurs widely even in some protected areas, and forest loss continues across much of its remaining range. This species qualifies for listing as Critically Endangered under criteria A2cd+4cd.
DESCRIPTION
Nearly all accounts of Manouria emys note it to be uncommon, rare or very rare, and declining: interviews indicated that forest labourers and hunter-gatherers in northeastern India and eastern Bangladesh would find between one and six animals per year, even when using dogs to find the tortoises; some of this information pertained to the 1980s (Das 1991, Choudhury et al. 2000). In 2018, the Singapore Workshop Participants considered M. emys overall Endangered in India, with a declining population trend. Recent records from India are only from Manipur, Mizoram, and Assam. Only three records of wild individuals have been reported in Assam since 2010, which have all been relocated to the zoo; and ten records from Manipur (S. Singh pers. comm 2018). It is considered Critically Endangered in Bangladesh and Myanmar (Participants, Singapore Red List Workshop 2011) and is apparently extirpated in the western side of Myanmar (K. Platt pers. comm. 2018). It was considered ‘rare’ in Indonesia by Samedi and Iskandar (2000) and very rare in Sumatra. It has been recorded in trade in Malaysia since 1989 and it was considered to occur most commonly in sparsely-populated hill and mountain areas.
Low collection rates of a few animals per year were reported by hill tribe hunter-gatherers in western Thailand in the early 1990s (Thirakhupt and van Dijk 1995). Taylor (1970) noted that ‘These large turtles are now becoming rare in Thailand. In 2005, the species was assessed as Endangered in the ONEP Red Data. More recently, Wanchais (2008) study in the well protected Kaeng Krachan National Park in Thailand found 15 individuals in a 1.5 km2, suggesting that relatively high densities may occur in appropriate habitat without human pressures. In central Borneo, the species is not rare in good forest habitats (I. Das pers. comm. 2018). In northeast India, the local communities are reporting fewer captured individuals for this species, although no data on population size or trends are available (M.F. Ahmed pers. comm. 2018). A few juvenile and adult individuals have been collected in the border of Bangladesh and Myanmar.
No population data appear to be available for the other portions of the species range.
Participants of the Singapore Red List Workshop (2018) suspected over 80% reduction in population has occurred over the past three generations (135 years) and will continue for at least another generation due to exploitation pressures and reduction in area of occupancy as a result of habitat degradation.
HABITAT AND ECOLOGY
Manouria emys exclusively inhabits evergreen forest, from lowland regions up to altitudes of about 1,000 m (typically 600-1,500 m). The animals appreciate moisture and are typically found near water and frequently burrow in damp soil (Nutphand 1979). Lambert and Howes (1994) radio-tagged a female at Danum Valley in Sabah. This animal ranged in an area of 0.6 km2 during 53 days of almost daily observation, her locations generally clustering for several days followed by a long walk of up to about 300 m, followed by another period spent in a limited area. Wanchai (2008) found the species to utilise a range of habitats, including bamboo forest, dry evergreen forest mixed with bamboo, dry evergreen forest, stream courses and swampy stream edges. Juveniles are rarely observed more than 20 m from streams; adults are also generally close to streams except during the raining season when they are seen to forage at greater elevations (Wanchai 2008). During the dry season, most individuals become inactive for a period of up to two months, buried in litter or under tree falls.
The diet has been reported to include bamboo shoots, tubers and other juicy vegetation (Nutaphand 1979) and some invertebrates and frogs (Humphrey and Bain 1990). Lambert and Howes (1994) observed their radio-tagged female feeding on 19 occasions, eating predominantly green leaves of understory plants and mushrooms, as well as some seedlings, sometimes including the roots, and fallen figs (Ficus punctata) on one occasion.
Animals of the nominate subspecies can reach up to 50 cm carapace length and 20 kg, while subspecies M. e. phayrei reaches 60 cm carapace length and 37 kg (Nutphand 1979). Size and age at maturity have apparently not been reported.
The social behaviour of this species is quite complex, with elaborate dominance and courtship rituals (described in captivity and illustrated in detail by McKeown et al. 1990). Lambert and Howes (1994) noted (attempted) matings of their radio-tagged female at Danum Valley during 6-9 March and on 16 April by a different male; another mating was observed on 14 May. In captivity, a nest is constructed by the female by sweeping leaf litter backwards to form a nest mound. In this mound, a clutch of on average 35 (range 15-51, N=24) spherical or slightly elongate eggs (41-54 mm diameter, weight 46-80 g) is laid, with larger females typically produces more eggs. The nest is defended against potential predators by the female during the first few days.
In captivity, M. e. phayrei reaches sexuality maturity at about 15 years (Fahz 2010). Longevity of this subspecies has been recorded up to 20 years, but it is likely to be much longer (Slavens and Slavens 2000). Generation length is estimated at about 45 years (three times age of maturity).
THREATS
Manouria emys is generally killed and butchered on the spot for its meat whenever encountered by local hunter-gatherers through much of its range, as well as collected for export trade for consumption in East Asia. Some wild-caught animals occur in global pet trade. The Turtle Survival Alliance confiscated 65 M. e. phayrei in Myanmar recently (Stanford et al. 2015). A total of at least 507 live specimens, in seven shipments, were reported as seized from illegal trade during the period 2000-2015 (CITES CoP17 Doc73).
This species is also threatened by shrinking habitat availability as lowland and mid-elevation evergreen forests are degraded and lost through logging, clearing for agriculture, forest fires, and hydroelectric dams and reservoirs and associated infrastructure, although its preference for rugged wet montane forests may offer some protection (Moll 1989, Thirakhupt and van Dijk 1995, Choudhury et al. 2000). In Northeastern India, most of the habitat exists in Reserved Forests outside protected areas, where slash and burn agriculture is in decline, being replaced by horticulture. Organised large bamboo-cutting efforts in forests impact the tortoises both by removing a prime food resource as well as the increased disturbance and detection probability. Ethnic violence is a regional issue, and resettlement sites tend to be located in forest areas. In Mizoram, at least ten individuals collected from a proposed dam site were held captive in Aizawal Zoo for ex situ conservation (M.F. Ahmed pers. comm. 2018).
USE AND TRADE
Manouria emys is generally killed and butchered on the spot for its meat whenever encountered by local hunter-gatherers through much of its range, as well as collected for export trade for consumption in East Asia. Some wild-caught animals occur in the global pet trade. The Turtle Survival Alliance confiscated 65 M. e. phayrei in Myanmar recently (Stanford et al. 2015). A total of at least 507 live specimens, in seven shipments, were reported as seized from illegal trade during the period 2000-2015 (CITES CoP17 Doc73).
CONSERVATION ACTIONS
Manouria emys is included in CITES Appendix II with all Testudinae spp., allowing international commercial trade in the species provided such trade is not detrimental to the species, and subject to national trade legislation. It is also included in Schedule IV of the Indian Wildlife (Protection) Act of 1972 (amended); it warrants revision to Schedule I. The species is protected under the Wildlife Conservation Act (2010) in Malaysia and trade is regulated. Manouria emys is protected under domestic legislation in Myanmar and under the Wildlife Preservation and Protection Act (1992) in Thailand. It is expected to be included under Government Decree No. 7 in Indonesia soon; in 2017 Indonesian quotas were set at 50 animals, under 20 cm, for the pet trade.
In India, the Nengpui Wildlife Sanctuary, North Cachar Hills and Nongkhyllem Wildlife Sanctuary are known to support wild populations in less disturbed habitats (Ahmed and Das 2010). In Bangladesh it occurs in the Sangu Wildlife Sanctuary (Rahman et al. 2015). In Myanmar, M. emys occurs in at least one protected area: Rakhine Yoma Elephant Sanctuary. In Thailand, the species occurs in several protected areas, including: Kaeng Krachan National Park, Mae Wong National Park, Khlong Lan National Park, Khao Pra Bang Kram Wildlife Sanctuary, Umphang Wildlife Sanctuary, Huai Kha Khaeng Wildlife Sanctuary, protected areas in the Nakhon Sri Thammarat mountains, and Bang Lang National Park in southern Yala Province (van Dijk and Thirakhupt 1995, Wanchai 2008; P.P. van Dijk pers. comm.). In Peninsular Malaysia, it occurs in one protected area: Taman Negara National Park (Lim and Das 1999, Norsham et al. 2000). In Indonesia, the species occurs in three protected areas: Gunung Leuser National Park, Danau Sentarum National Park, and Kerinci Seblat National Park. In Sabah, Malaysia, the species occurs in at least two protected areas: Tabin Wildlife Reserve (Høybye-Mortensen 2004) and Danum Valley Conservation Area (Lambert and Howes 1994).
Assurance colonies of M. emys exist both in-range and ex situ, but maintaining large enough groups in captivity to maintain genetic diversity is beyond what is logistically feasible. Three such facilities currently exist in Myanmar alone, with others established or proposed throughout southern Asia. A large assurance colony of 24 M. e. phayrei has been established at the Zeepin Forest Reserve in Shan State, Myanmar. An assurance colony composed of village-confiscated M. e. phayrei has been established at the Rakhine Yoma Elephant Sanctuary in Myanmar. A much large assurance colony has been established at the Mandalay Zoo in Myanmar, which will be stocked with confiscated animals (Turtle Survival Alliance, unpubl. data 2012). Captive breeding by animals currently maintained in captivity can easily meet hobbyist market for this species, and a complete trade ban on wild-collected animals should be considered.
Captive populations are kept in a variety of zoos and other facilities (India, Sarawak), and can form the nucleus of captive breeding programs for eventual re-introduction. Training on husbandry and captive management is needed, as well as development of a strategy to replenish wild populations with captive-produced specimens.
The survival of the species outside protected areas seems unlikely, and effective protection of existing and perhaps additional protected areas will be key to its survival in the wild. Additionally, raising public awareness and utilising eco-tourism techniques may help to reduce poaching in protected areas. Additional survey efforts are needed across the species range. As the species occurs mostly outside protected areas or within exploited protected areas, community-based conservation could improve the conservation scenario faster in the northeast India (M.F. Ahmed pers. comm. 2010). Updated status, especially in protected areas, is urgently needed, and more ecological information is desirable, as is detailed range-wide genetic and taxonomic characterisation of populations, particularly regarding subspecies in northeast Indian states. Captive breeding programs are required in Indonesia to sustain the population. |
