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Camera-trap evidence that the silver-backed chevrotain Tragulus versicolor remains in the wild in Vietnam

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In an age of mass extinctions, confirming the survival of lost species provides rare second chances for biodiversity conservation. The silver-backed chevrotain Tragulus versicolor, a diminutive species of ungulate known only from Vietnam, has been lost to science for almost three decades. Here, we provide evidence that the silver-backed chevrotain still exists and the first photographs of the species in the wild, and urge immediate conservation actions to ensure its survival. Interviews with local people and camera-trap surveys have led to the first scientifically confirmed sightings of the silver-backed chevrotain for more than 25 years. The news that this species is not extinct is tempered by major threats of habitat loss and poaching in the region.
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Brief CommuniCation
https://doi.org/10.1038/s41559-019-1027-7
1Global Wildlife Conservation, Austin, TX, USA. 2Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany. 3Southern Institute of Ecology,
Vietnam Academy of Science and Technology, Ho Chi Minh City, Vietnam. 4NCNP, Ninh Thuan Province, Vietnam. 5Borneo Futures, Bandar Seri Begawan,
Brunei Darussalam. 6University of Queensland, Brisbane, Queensland, Australia. 7Center for the Conservation of Tropical Ungulates, Punta Gorda, FL, USA.
8These authors contributed equally: An Nguyen, Andrew Tilker. *e-mail: atilker@globalwildlife.org
In an age of mass extinctions, confirming the survival of lost
species provides rare second chances for biodiversity con-
servation. The silver-backed chevrotain Tragulus versicolor,
a diminutive species of ungulate known only from Vietnam,
has been lost to science for almost three decades. Here, we
provide evidence that the silver-backed chevrotain still exists
and the first photographs of the species in the wild, and urge
immediate conservation actions to ensure its survival.
The Greater Annamites Ecoregion of Vietnam and Lao PDR
contains one of the highest concentrations of endemic mammal
species found anywhere in a continental setting1; it has a par-
ticularly diverse suite of endemic ungulates1. Unfortunately, the
distribution and population sizes of its endemic ungulate species
have been severely reduced from historical levels due to anthro-
pogenic pressures24. Habitat loss has been a major factor in these
declines1, especially in Vietnam5, but a more substantial threat to
the regions ungulates is the widespread and intensive hunting,
which supplies the thriving wildlife trade in Indochina6,7. Hunting
of terrestrial mammals in the Annamites is primarily accomplished
by the setting of indiscriminate wire snares8,9. Snaring is almost
ubiquitous across the Annamites and has resulted in widespread
empty forest syndrome’10. Exceptionally high levels of snaring have
driven two endemic ungulates, the saola Pseudoryx nghetinhensis
and the large-antlered muntjac Muntiacus vuquangensis, to the
brink of extinction24.
Among the least-known ungulates in the Greater Annamites
Ecoregion is the silver-backed chevrotain T. versicolor11. The silver-
backed chevrotain was first described in 1910 from four specimens
that were obtained near the city of Nha Trang, Vietnam12 (Fig. 1).
The exact localities for the specimens were not provided in the
original publication12, possibly because they were acquired in trade.
Several morphological features distinguish the silver-backed chev-
rotain from the more widespread lesser chevrotain Tragulus kanchil.
The most distinctive external characteristic of the silver-backed
chevrotain is its unique two-tone pelage coloration, with an ocher-
ous-buff anterior and a silver or grey posterior1215. The grey hairs
are conspicuously tipped with white, giving the posterior a grizzled
appearance13. Another distinguishing characteristic is the absence
of the dark transverse throat stripe that is present in the lesser chev-
rotain. In the silver-backed chevrotain, the ocherous throat lines
converge but do not touch; the white ventral coloration is therefore
contiguous from the throat to the underbelly1315.
Other than the four specimens that were used to describe the
species, only a single verifiable record exists11. In 1990, a joint
Vietnamese–Russian expedition in the Gia Lai province obtained a
hunter-killed chevrotain in the vicinity of Dak Rong and Buon Luoi
that was later identified as silver-backed chevrotain13. The specimen
shows the pronounced bi-coloration and non-convergent throat
markings that are characteristic of the species (Fig. 2a). Notably, an
additional 24 chevrotain specimens were collected from the area
between 1978 and 1993 as part of the joint expeditions, but there are
no additional silver-backed chevrotain records13. The Gia Lai speci-
men provides limited insights into the ecology of the species. The
area that the specimen was recorded from was described as mature
lowland semi-evergreen tropical forest13. The record suggests sym-
patry with the lesser chevrotain13, although locality information is
not precise enough to indicate syntopy11. However, the most impor-
tant consequence of the Gia Lai specimen was the confirmation that
the silver-backed chevrotain was still extant13,16.
Following the identification of the Gia Lai specimen, Kuznetsov
and Borissenko13 and Meijaard etal.16 called for follow-up surveys
to assess the distribution and conservation status of silver-backed
chevrotain. In their 2004 publication describing the Gia Lai sil-
ver-backed chevrotain, Kuznetsov and Borissenko noted that,
by the mid-1990s, the area around Dak Rong and Buon Luoi had
undergone severe deforestation13. The authors also suggested that,
over the course of the 1978 to 1993 surveys, hunting pressure had
already resulted in chevrotain declines13. Despite these warnings,
no follow-up search efforts appear to have taken place, and there
were no confirmed records of the species for more than 25 years.
Given the considerable increase in hunting pressure that has
occurred in Vietnam since the early 1990s17, it was unclear whether
the species still existed. Once again, the silver-backed chevrotain
became a lost species.
We conducted targeted surveys to search for the silver-backed
chevrotain. First, we used interview surveys to obtain information
on the occurrence of potential silver-backed chevrotains in the
vicinity of Nha Trang, then conducted follow-up camera-trapping
in the most promising area. Interviews were conducted in three
Vietnamese provinces and covered four forest blocks, only one of
Camera-trap evidence that the silver-backed
chevrotain Tragulus versicolor remains in the
wild in Vietnam
An Nguyen1,2,8, Van Bang Tran 3, Duc Minh Hoang 3, Thi Anh Minh Nguyen3, Dinh Thang Nguyen4,
Van Tiep Tran4, Barney Long1, Erik Meijaard 5,6, Jeff Holland7, Andreas Wilting 2 and
Andrew Tilker 1,2,8*
NATURE ECOLOGY & EVOLUTION | VOL 3 | DECEMBER 2019 | 1650–1654 | www.nature.com/natecolevol
1650
Content courtesy of Springer Nature, terms of use apply. Rights reserved
... Those that were perceived as high risk included the white-faced plover, Gongshan muntjac (Muntiacus gongshanensis), silver-backed chevrotain (Tragulus versicolor), Williamson's chevrotain (Tragulus williamsoni), and the leaf muntjac (Muntiacus putaoensis). These Cetartiodactyla species are herbivorous ground foragers and are all recent discoveries to science being described from only a small number of specimens (Kloss, 1916;Ma et al., 1990;Amato et al., 1999) and a recent rediscovery in 2018 of the silver-backed chevrotain (Nguyen et al., 2019). Although the primary threats to these Cetartiodacyla species is habitat degradation and poaching Meijaard et al., 2017;Nguyen et al., 2019) any additional pressures from domestic dogs could halt their recovery. ...
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Camera trapping is a widely applied method to study mammalian biodiversity and is still gaining popularity. It can quickly generate large amounts of data which need to be managed in an efficient and transparent way that links data acquisition with analytical tools. We describe the free and open-source R package camtrapR, a new toolbox for flexible and efficient management of data generated in camera trap-based wildlife studies. The package implements a complete workflow for processing camera trapping data. It assists in image organization, species and individual identification, data extraction from images, tabulation and visualization of results and export of data for subsequent analyses. There is no limitation to the number of images stored in this data management system; the system is portable and compatible across operating systems. The functions provide extensive automation to minimize data entry mistakes and, apart from species and individual identification, require minimal manual user input. Species and individual identification are performed outside the R environment, either via tags assigned in dedicated image management software or by moving images into species directories. Input for occupancy and (spatial) capture-recapture analyses for density and abundance estimation, for example in the R packages unmarked or secr, is computed in a flexible and reproducible manner. In addition, survey summary reports can be generated, spatial distributions of records can be plotted and exported to gis software, and single- and two-species activity patterns can be visualized. camtrapR allows for streamlined and flexible camera trap data management and should be most useful to researchers and practitioners who regularly handle large amounts of camera trapping data.
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