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Tragulus versicolor

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA CETARTIODACTYLA TRAGULIDAE

Scientific Name: Tragulus versicolor
Species Authority: Thomas, 1910
Common Name(s):
English Silver-backed Chevrotain, Vietnamese Mousedeer
Taxonomic Notes: Thomas (1910) described this taxon as a new species noting differences from both T. napu and T. kanchil, but almost all subsequent authors subsumed the taxon within T. napu, from which it is apparently widely disjunct (contra the map in Corbet and Hill 1992). Meijaard and Groves (2004a), however, measured three of Thomas’s specimens and showed the taxon to fall well outside T. napu in morphological characters, and to form a grouping (based on skull measurements) well differentiated from all other Tragulus species.

Assessment Information [top]

Red List Category & Criteria: Data Deficient ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Timmins, R.J., Duckworth, J.W. & Meijaard, E.
Reviewer(s): Black, P.A. & Gonzalez, S. (Deer Red List Authority)
Justification:
There is no information on the current range or population status of T. versicolor because of a lack of appropriate survey work for the species in appropriate areas of Viet Nam: the areas where it is most likely to occur have not been well surveyed, and appropriate methods such as camera-trapping and specimen collection have been even less extensive. Therefore the species cannot be assessed against range size or, directly, population trend criteria. No strong ecological correlates are known sufficient to allow inferential assessment of population trends through habitat trends. The species' resilience to hunting is not known. Therefore, T. williamsoni is listed as Data Deficient because assessment of the taxon against red list criteria is not possible. Although there is only one record since 1907, there is no reason to consider it a Possibly Extinct Candidate, because the paucity of records is assumed to reflect the lack of suitable survey (see above). A more informed future judgment when sufficient data are available are likely to indicated that it is threatened. The population is almost certainly declining due to severe hunting pressure for ground-dwelling mammals, resulting in population reductions of even the most resilient species; it may be found to warrant a very high threat category particularly as there is no evidence of presence in high altitudes.

Geographic Range [top]

Range Description: The specimens used by Thomas (1910) to describe this species were acquired at Nhatrang on the coast of southern Viet Nam (12°15'N 109°10'E). The provenance of the specimens cannot be certain, although there is no specific reason to doubt it, because they may have been acquired in trade. Another specimen was obtained from local hunters on 16 January 1990 at about 500 m asl near the River Tra (a tributary of the River Ba) around Dak Rong and Buon Luoi, about 20 km north of Kan Nack (Gia Lai province, Viet Nam) and is now held at the Zoological Museum of Moscow University (Kuznetzov and Borissenko 2004). The true distribution of the species is unknown, because there has been very little conscious knowledge of the species, so surveys have not sought it; many have assumed that only one Tragulus occurs in most of Indochina and therefore not critically identified records. Confusion was fomented by the widespread inclusion of T. versicolor within T. napu, although in many external characters T. versicolor is more like T. kanchil than it is T. napu (Meijaard and Groves 2004a; R. J. Timmins pers. comm. 2008), meaning that even surveyors who thought they had correctly excluded ‘the second Indochinese chevrotain’ from their records of T. kanchil (then referred to as T. javanicus) had not in fact done so (e.g. almost all records from Lao PDR in the 1990s). Few, if any, records of Tragulus from Indochina other than those in Meijaard and Groves (2004a) and in Kuznetzov and Borissenko (2004) have been positively identified to species using criteria that could distinguish T. versicolor from T. kanchil. However, the species is certainly not as widespread as T. kanchil in Indochina (which is known from a scattering of specimens from throughout southern and central Indochina; Meijaard and Groves 2004a; E. Meijaard pers. comm. 2008), and analysis of Tragulus photos (by R.J. Timmins pers. comm. 2008) from camera-traps from a number of localities (central Annamites: Quang Nam; B. Long/WWF; Virachey NP; Huy Keavuth/WWF; Northern Annamites: Nakai-Nam Theun NPA; W.G. Robichaud/J. Johnson/WMPA; eastern Cambodian lowlands; Huy Keavuth/WWF) have either been of unidentifiable chevrotains or more commonly have certainly been of T. kanchil (R.J. Timmins pers. comm. 2008). The same appears to be true of photos from camera-traps from Siema Biodiversity Conservation Area in eastern Cambodia (J. Walston pers. comm. 2005 to R.J. Timmins pers. comm. 2008).

T. versicolor would be difficult to separate confidently from T. kanchil especially under field conditions and this is so even on photographs. Thus, building knowledge on the species is likely to prove difficult and time consuming (R. J. Timmins pers. comm. 2008). Distinguishing characters were discussed by Meijaard and Groves (2004a) and by Kuznetzov and Borissenko (2004). The latter, admittedly on the basis of a single specimen which, lacking a skull, could not be aged, confirmed the pelage pattern differences described in the earlier source, but suspected that T. versicolor might be smaller than sympatric T. kanchil, rather than consistently larger.
Countries:
Native:
Viet Nam
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: There is no meaningful way of estimating population levels or trends. The paucity of records of the species cannot be taken as evidence of real rarity because of the likelihood that records of the species have in the past been mistakenly identified as T. kanchil (R.J. Timmins pers. comm. 2008). Kuznetzov and Borissenko (2004) stated that the specimen they identified as T. versicolor in 2004 had been noted at time of collection (1990) as oddly coloured, and that none of the other 24 chevrotains examined in the Buon Luoi area in the 1978–1993 period were similar. Also, the same team’s investigations further south on the Tay Nguyen plateau were quite extensive, and encountered and collected many chevrotains without any other specimens of T. versicolor having come to light in the Russian collections (Viet Namese ones have apparently not been checked). Retrospective statements without the specimens to hand can only be provisional and moreover even if the low ratio around Buon Luoi is genuine, this might simply reflect suboptimal habitat for the species at that site (e.g. through altitude, humidity, underlying geology). It cannot be taken as indicating that T. versicolor is generally rare across its range. It is impossible to determine whether T. versicolor is genuinely specialised to certain habitat types within a restricted range, or a common species (perhaps even the predominant chevrotain species) over wide areas of southern Indochina from where there is very little information on Tragulus rigorously identified to species (R.J. Timmins pers. comm. 2008).
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: Speculation on habitat and altitudinal preferences are complicated by the diverse range of habitats (from deciduous to evergreen) and the abrupt changes in altitudinal range (sea-level to 500 m asl) in the two localities for which evidence of presence comes (R. J. Timmins pers. comm. 2008), taking Nhatrang as a true locality. The 1990 specimen came from an area from where 24 specimens of T. kanchil were collected during 1980–1993, indicating sympatry, although records are not located precisely enough to speculate on actual syntopy (Kuznetzov and Borissenko 2004).
Systems: Terrestrial

Threats [top]

Major Threat(s): Threats to the species are little more than speculation. The forests of Viet Nam are subject to very high levels of indiscriminate hunting especially snaring for small game such as chevrotains and civets (Timmins and Duckworth 2000; Timmins et al. 2007; R.J. Timmins pers. comm. 2008) and specifically this is so around Buon Luoi (Kuznetzov and Borissenko 2004). In general, hunting pressure may be somewhat lower in southern regions of the country although this region is less well known when compared with the northern Annamites and the northern parts of the Central Annamites (R.J. Timmins pers. comm. 2008). Whether this species would be able to cope with high hunting levels is not yet debatable as there are no relevant data, but some congeners persist in the face of very heavy hunting, even in fragmented and degraded landscapes (see 2008 Red List accounts of other Tragulus). Declines in T. versicolor are very likely to have happened to some extent, because even the most resilient ground-dwelling species in chevrotain size-class occur in unnaturally low densities in most forest areas of Viet Nam (Timmins et al. 1999; Timmins and Trinh Viet Cuong 2001; R.J. Timmins pers. comm. 2008). Spotlight surveys in protected areas around Buon Luoi totalling 100 hours in about year 2003 found no chevrotains (Kuznetzov and Borissenko 2004), but the significance of this is unclear, as chevrotains are absent or exceptionally rare in various Lao forests whence they cannot plausibly have been eradicated, given their persistence in other more heavily hunted and degraded areas (see 2008 account for T. kanchil). Hunting patterns are similar in Lao PDR and Cambodia, which may also be found to support the species, although the intensity and severity of hunting is generally less than in Viet Nam, but on the increase (R.J. Timmins pers. comm. 2008).

Habitat degradation and fragmentation may also be threats, depending on how well the species persists in such areas. These processes occur widely in the species' known range and throughout its plausible range. Habitat conversion is more likely to reduce or eliminate populations where it occurs, although there is no evidence of whether T. versicolor can use plantation crop landscapes. By the mid 1990s the area around Buon Luoi had been completely deforested and converted to agriculture (Kuznetzov and Borissenko 2004). Although protected areas remain in the general region, all are being logged and heavily hunted (Kuznetzov and Borissenko 2004). No information is available on the current status of the habitat whence came the original material, because this is not known precisely.

Conservation Actions [top]

Conservation Actions: Surveys (if possible combined with those for other poorly known and regionally endemic mammals) in the Southern Annamites and southern portions of the Central Annamites (in Viet Nam, Cambodia and Lao PDR) at a range of altitudes and in various habitats are urgently required to document the species’s range, status, and habitat and altitudinal preferences, using appropriate methods such as camera-trapping and specimen collection. Kuznetzov and Borissenko (2004) urged for particular attention to be paid to forests persisting around Nhatrang and Buon Loui; but given the lack of ecological similarities between these areas, either the Nhatrang location is in error or the species has a wide ecological tolerance. In either case, this urges surveys to be extensive rather than focussed on only these two areas. The suggestion in Meijaard and Groves (2004b) that "the main external differences between T. kanchil and T. versicolor are distinctive and it is likely that, if T. versicolor still exists, local hunters will know both species" should not be taken to suggest that village information alone would be a suitable survey method, rather that it may help in determining where to invest time and effort in camera-traps. After examination of three of Thomas’s (1910) specimens alongside specimens of T. kanchil from Indochina, R.J. Timmins (pers. comm. 2008) thought that field identification of Tragulus (or from photogpaphs) should be done very cautiously, and that there could be circumstances for confusion; experience with muntjacs Muntiacus in Indochina urges caution with both field identification and use of villager information in surveying for species (Timmins et al. 1998; R.J. Timmins pers. comm. 2008).

Until one or more populations are found, further conservation measures cannot be recommended additional to the general need to consolidate the declared protected areas in southern Indochina into functioning biodiversity conservation areas.

Citation: Timmins, R.J., Duckworth, J.W. & Meijaard, E. 2008. Tragulus versicolor. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 01 September 2014.
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