This species is found in lowland/foothill primary and secondary forests as well as cultivated areas up to 600 m in elevation (Semiadi and Boeadi pers. comm.). The habitat of this species is a mosaic of riverine, seasonal swamp and dry undulating country, vegetated predominantly by legumes and dipterocarps. In Sabah, it also inhabits mangrove forest. In Peninsular Malaysia, it feeds on shoots, young leaves and fallen fruits in the tall forest of the lowlands. During the day it may prefer crown-gap areas with dense undergrowth of creeping bamboo, and move to higher and drier ridge areas at night. All Tragulus species are associated with forests, but there is strong evidence that T. kanchil does not require old-growth forest or even particularly mature secondary forest. Its heavy use of disturbed habitats was confirmed by Matsubayashi et al. (2003), who found that in Kabali-Sepilok (Sabah), T. kanchil fed primarily in crown-gap areas dominated by bamboo stands, probably because it prefers fruits and soft leaves of pioneer plants with lower concentrations of secondary metabolites. Later, at another site in Sabah, Matsubayashi and Sukor (2005) again found a strong association of T. kanchil with immature forest. Johns (1997) found Tragulus to be more common in logged forests than in mature forests in Peninsular Malaysia, and densities tended to decrease again as logged forests matured. The abundance of Tragulus spp. (T. napu and T. kanchil combined, with no information on the proportions or even confirmation that both species were present) was higher (strongly statistically significantly so) in areas within 1 km inside the boundary of Bukit Barisan Selatan National Park, Sumatra, than in the interior of the park, suggesting higher numbers in somewhat encroached habitat (O'Brien et al. 2003); note that it is not confirmed that this information refers to T. kanchil. The genus (presumably including this species) was ubiquitous in a study in West Malaysia which paired each of seven of virgin jungle reserves with a nearby unprotected area with seriously encroached habitat (Laidlaw 2000). By contrast, at the Danum Valley, Sabah (East Malaysia), densities of T. kanchil were 21–39 animals per km² in primary forest but only 10–15 animals per km² in selectively logged areas (and there was an even bigger decrease of 55–66% for T. napu); in this area, where hunting is negligible and so is not confounding patterns, chevrotain densities were positively correlated with fruit abundance, and negatively correlated with pioneer trees and grass and herbs (Heydon 1994; Heydon and Bulloh 1997; Davies et al. 2001). Heydon and Bulloh (1997) suggested the obligate frugivory of chevrotains limited their ability to compensate for logging-led loss of fruit trees by browsing the abundant regrowth of logging areas. This may be significant in rationalising the differences between areas concerning the apparent effects of logging on the species: in some logging areas, fruiting trees are common along streams and tend to be left, and pioneer colonists produce abundant edible fruit. Around Buon Luoi, southern Viet Nam, most encounters with chevrotains (assumed to be largely or entirely this species rather than T. versicolor, based on ratios of specimens) were in places where tall forest alternated with scrub thickets, patches of grassland and moist riverine habitats. Riverbank slopes appeared particularly favourable to chevrotains (Kuznetzov and Borissenko 2004). E. Pollard (pers. comm. 2008) sees Lesser Chevrotains commonly in highly degraded forest in Mondulkiri province, Cambodia. In Thailand, R. Steinmetz (pers. comm. 2008) finds the species commonly in edge habitats, also widely, but probably less frequently, within big blocks of closed-canopy forest. By contrast in Lao PDR, the genus seems to be scarce in the interior of old-growth forest, based on surveys of many of the country’s remaining forests. Chevrotains have been camera-trapped in at least one protected area (Nakai–Nam Theun NPA), but only in one part of that (Johnson and Johnston 2007); the report does not discuss habitat. Tracks are readily identified by those familiar with them, but are rarely found within heavy forest in Lao PDR (R.J. Timmins pers. comm. 2008). Chevrotains are easily spot-lit at night where they occur, yet extensive spotlighting in south and central Lao PDR during 1992–1996, with most of such survey in areas below 550 m asl, found the species only once, and there were not many more records by day (Duckworth et al. 1994; Duckworth 1996, 1998; Evans et al. 2000; and a lack of records in many other sources). All or nearly all the handful of sightings (day or night) were in edge or heavily degraded areas (J.W. Duckworth pers. comm. 2008), but some lengthy surveys of lowland encroached forest failed to find the genus (notably in the ‘corridor’ sector of Phou Xang He NPA). This indicates a general overall rarity, or at least a localised distribution, either natural or human-induced. The apparently large numbers on the Vientiane plain (see Threats; Srikosamatara et al. 1992) (at the time of surveys perhaps among the most intensively hunted areas of Lao PDR for mammals of this size-class), including persistence at dreadful sites like Houay Nhang (whence almost all mammals larger than rats had been hunted out; see Threats), argues against human agency being responsible for the absence or low densities of chevrotains elsewhere in lowland Lao PDR in places like the corridor of Phou Xang He NPA and interior forests. Extensive surveys in the 1990s of Lao forest areas suggests almost certainly that in extensive tracts of semi-evergreen and evergreen forest below 1,000 m asl chevrotains are naturally scarce at least away from ‘edge areas’, because hunting pressure from snares, dogs, and day and night hunting with guns is relatively low, and other quarry species captured in similar ways to chevrotains are often common (R.J. Timmins pers. comm. 2008). In contrast, Kuznetzov and Borissenko (2004), who concurred that, in Viet Nam, closed-canopy forests often support few if any chevrotains, proposed that this is an artificial pattern produced through hunting (see Threats). In Lao forest ‘edge’ areas the very low numbers of chevrotains cannot necessarily be concluded to be a natural pattern, as these ‘edge areas’ tend to be in the vicinity of human settlements and in at least the 1990s experienced high levels of snaring and gun hunting (primarily by day) for primarily local consumption or local markets and ubiquitous hunting dog presence (R.J. Timmins pers. comm. 2008). Experiences in 2005, however, suggest that chevrotain presence is perhaps highly patchy and correlated to specific habitat features, as in the Nam Kading National Protected Area there was a clear hunting focus on chevrotains with an evidently significant capture rate; yet general wildlife field surveys in 2005 and 1995 observed the species in the field only once, despite significant spotlighting effort (Evans et al. 2000; Timmins and Robichaud 2005; W.G. Robichaud pers. comm. to R.J. Timmins 2005; R.J. Timmins pers. comm. 2008). It suggests that the species is tied to specific microhabitats; perhaps this might be related to water requirements as there is a surprising regularity with which authors note commonness in riverine areas. Dumas’s (1944) description of the distribution in Cambodia strongly echoes modern findings that it is localised in Lao PDR and associated with gaps in Sabah: he stated that it was absent from heavy forest of tall trees without understory, and in general it was localised in occurrence but found somewhere in each of most of the forested provinces of Cambodia, wherever there are low, dense, thickets, and within clumps of bamboo, of which it is fond of the young shoots. Such a pattern 70 years ago seems unlikely to have been produced by hunting. In sum, the habitat use of this species with respect to edge–interior areas shows startling heterogeneity, at least in non-Sundaic areas, but this cannot yet be explained; in particular, disentangling the contributions of intrinsic habitat suitability and the effects of hunting is difficult. The Lesser Oreiental Chevrotain may even be able to survive in large numbers in plantation landscapes: in the Sarawak Planted Forests, Bintulu, Sarawak, Belden Giman (pers. comm. 2008) has many records from Acacia mangium plantations both mature and immature. However, this landscape contains many patches of secondary and old-growth forest (Belden et al. 2007), so further study is needed to assess use, if any, of landscape-level monocultures. Most of this chevrotain’s geographic range is dominated by evergreen or semi-evergreen forests, but large areas of Cambodia, Thailand and to a lesser extent Lao PDR and Viet Nam are deciduous. One survey in Mondulkiri province, Cambodia, in 2008, found chevrotains to be widespread and common in mixed deciduous forest, dominated by e.g. Lagerstroemia spp., but they were not found in nearby deciduous dipterocarp forest (C. Starr pers. comm. 2008). In this same general area, J. Walston (pers. comm. 2008) also found them commonly in mixed deciduous forest, during 2002–2006. Field surveys of extensive landscapes of deciduous dipterocarp forest and mixed deciduous forest (in which ground fires are almost annual) in eastern and northeastern Cambodia (including Mondulkiri) have not detected the species (R.J. Timmins pers. comm. 2008) and camera-trapping from the same landscapes also suggest chevrotains are absent from deciduous regularly burnt forest tracts, but occur in semi-evergreen forest patches within the same landscapes (WWF unpublished data). Dumas (1944) stated that chevrotains were unknown in the deciduous dipterocarp forests of Cambodia, No other information on their use of deciduous landscapes has been traced; it is probable that even within deciduous dipterocarp forest they might use the semi-evergreen riverine strips within. The Lesser Oriental Chevrotain may be absent from highlands throughout much of its range, and seems to be an extreme lowland specialist in some areas. The clearest analysis, from Borneo, found that it lived mostly below 100 m asl, with no record above 600 m asl (Payne et al. 1985). The maximum altitude in Indonesia (i.e. Borneo and Sumatra) is also said to be 600 m asl (G. Semiadi and Boeadi pers. comm. 2006); specific information from Sumatra has not been traced. In Lao PDR most known sites (see Duckworth et al. 1994, Duckworth 1996, Evans et al. 2000) are also below 600 m asl; however, chevrotains are abundantly hunted in the Nam Ha NPA which has a minimum altitude of 560 m asl (and rises to nearly 2,100 m asl) and is almost entirely rugged (Johnson et al. 2003), although these are perhaps more likely to be T. williamsoni than T. kanchil. There is a chevrotain specimen from Thateng on the Bolaven plateau (FMNH 38012) confirmed as T. kanchil (E. Meijaard pers. comm. 2008), suggesting occurrence at 800–1,200 m asl, although a short-distance trade origin may be possible. A recent finding of the genus being common in one part of Nakai–Nam Theun NPA (Johnson and Johnston 2007) gives no information on altitude of the records, and there are too few relevant specimens to allow a firm prediction as to which species they relate. Good populations certainly occur well above 600 m asl in Thailand: chevrotains are common in the degraded and edge habitats around Khao Yai National Park headquarters at 760–800 m asl (J. W. Duckworth pers. comm. 2008) and a number of specimens from nearby Pakchong suggest that these are likely to be T. kanchil, rather than unsuspected southerly occurrence of T. williamsoni. Also in Thailand, at Phu Khieo Wildlife Sanctuary chevrotains were camera-trapped commonly at 700–900 m asl, although the species involved is/are unclear (Lynam et al. 2001; A.J. Lynam pers. comm. 2008). Lesser Chevrotains visit saltlicks regularly (Matsubayashi et al. 2007). Lesser Chevrotain is often stated to be nocturnal, but in fact most activity is diurnal (in the first few and last few hours of daylight), with animals spending most of the night resting (Matsubayashi et al. 2003; Matsubayashi and Sukor 2005). It is highly solitary (Matsubayashi et al. 2006). Apparent territorial behaviour has been observed (Davison 1980); home ranges and core areas overlap considerably between males and females but core areas are completely separate between individuals of the same sex (Matsubayashi et al. 2006). Males are highly philopatric but females establish new home ranges when giving birth (Ahmad 1994 in Meijaard et al. 2005). Matsubayashi et al. (2003) estimated home-range size for females at 4.3 ha and for males 5.9 ha using the minimum convex polygon method, but the difference between males and females was not significant. The mean daily distance travelled for males was 519 ± 89 m, that for females 574 ± 220 m. The Lesser Chevrotain is partly frugivorous, but also eats substantial quantities of shoots and young leaves, mostly of fast-growing gap species rather than closed forest understory species; the latter tend to be richer in secondary protective compounds (Dang Huy Huynh 1968; Medway 1983; Kuznetzov and Puzachenko 1992; Matsubayashi et al. 2003). Among fruits, those of mass 1–5 g and seeds of mass 0.01–0.5 g are particularly taken (Heydon and Bulloh 1997). It seems to be facultively monogamous–polygymous (given the congruence between core areas of individual males and females with a conspecific of the opposite sex; Matsubayashi et al. 2006), with post-partum oestrus, females being almost continuously pregnant (Cadigan 1972 in Meijaard et al. 2005). The gestation period is 140–177 days (Lekagul and McNeely 1977), with 2–3 young per year, the fawns kept hidden (Meijaard et al. 2005).
The Lesser Oriental Chevrotain is listed as Least Concern because it was historically proven to be widespread and common, and chevrotains remain in large numbers in its specimen-validated range and at least in non-Sundaic areas persist in environments of very heavy forest degradation and fragmentation and hunting. The presumed short generation length of the species, considered to be likely under five years, also influences assessment, in that, for decline criteria to be invoked in Red Listing one would have to assume relatively high rates of decline over a large part of the species range in a relatively short window of time (10-15 years). Thus although there may be/have been drastic (local) reductions, these have probably not been synchronous over a large enough area. There are several major uncertainties, although these are not adjudged sufficient for listing as Data Deficient: (1) a rather low proportion of modern records of Tragulus from both the Sundaic and non-Sundaic portions of the range have been identified conclusively to species; (2) the conflicting nature of the information available concerning the effects of hunting (harvest levels are locally very high) and habitat destruction; (3) strong indications that in its non-Sundaic range it is localized in occurrence, a pattern for which the reasons remain opaque, but which has been proposed to result from hunting; (4) the apparent restriction to the extreme level lowlands in at least Borneo, placing it within the altitudinal zone of rapid forest loss.
CLASS : Mammalia
ORDER : Cetartiodactyla
FAMILY : Tragulidae
GENUS : Tragulus
SPECIES : Lesser Oriental Chevrotain (Tragulus kanchil)
Conservation status : Least Concern
Update : 11 April 2017