Overview

Distribution

Range Description

Tragulus napu, as constituted here (that is, excluding T. versicolor of Indochina and T. nigricans of the Philippines) occurs in the Sundaic subregion, extending some way up the Thai–Malay peninsula, in the following countries: Brunei, Indonesia (Kalimantan, Sumatra, and many small islands), Malaysia (West Malaysia, Sabah, Sarawak, and many small islands), Myanmar (far south only), Singapore (Pulau Ubin only), and Thailand (south only) (Meijaard and Groves 2004, Chua et al. 2009). Grubb (2005) also included Cambodia, Lao PDR, and ‘Indochina’ in the range of T. napu; but this was founded on the assumption that because T. versicolor, formerly considered a subspecies of T. napu, occurred in Viet Nam, T. napu must presumably occur in intervening Lao PDR and Cambodia. There is, for example, a map of such a conterminous range for T. napu in Corbet and Hill (1992). There is no evidence of such a distribution and, given the distribution patterns of other species, absolutely no reason to expect that it would have such a range, even if T. napu and T. versicolor are closely allied. Recent surveys in both countries have not suspected the species (Duckworth et al. 1999, R.J. Timmins pers. comm. 2008).

The northern limit on the Thai–Malay peninsula is not well clarified. Despite fairly intensive camera-trapping in Kuiburi National Park, Thailand (12°N and thus within the generally-assumed range for T. napu), Greater Chevrotain has not been photographed there. It must be scarce in this park if it occurs at all (Steinmetz et al. 2007, R. Steinmetz pers. comm. 2008).

Caution is needed in interpreting modern records of T. napu from anywhere outside the specimen- and photograph-validated range (as presented in Meijaard and Groves 2004); some camera-trap studies seem to have taken an essentially arbitrary attitude on naming their photographs of chevrotains, resulting in published listings of T. napu from, for example, northern Thailand. Because such listings never highlight the significance of such records, let alone discuss them, all are assumed to be in error, and are not discussed further, here.
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Geographic Range

Larger Malay Mouse Deer are located in Thailand, Indochina, Sri Lanka, the Malayan Penninsula, and the islands of Sumatra and Borneo.

Biogeographic Regions: oriental (Native )

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Physical Description

Morphology

Physical Description

This mouse deer, first described by F. Cuvier in 1822, is one of the smallest living hoofed mammals, along with the other three species in this genus. This ungulate has a small, triangular head with a small pointed black nose and large eyes. Approximately the size of a rabbit, they have very long and thin legs and a rounded body. The color is orange-brown with white under the stomach, chest and chin. These ungulates do not have any horns or antlers although the males have small tusks (elongated canines) in their upper jaw. When standing, their hind end is higher than their front quarter. Some measurements of the Mouse Deer is that their body length is 70-75 cm, their shoulder height is 30-35 cm and their tail length is 8-10 cm.

Range mass: 5 to 8 kg.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
The Greater Oriental Chevrotain is almost completely sympatric with T. kanchil, but the degree of syntopy is less clear. In the lowlands of Borneo both occur but T. napu apparently ranges to higher altitudes (up to at least 1,000 m asl) than does the latter (Payne et al. 1985). Relevant comparisons have not been traced for the other main occupied landmasses. Duckworth (1995) considered that the chevrotains demonstrably common at Similajau National Park were largely or entirely Greater, but on altitude use as given in Payne et al. (1985) it would seem surprising if Lesser did not occur. However, Matsubayashi and Sukor (2005) found at Tabin Wildlife Reserve, Sabah, that T. kanchil was almost absent from mature forest, all animals in such habitats being T. napu. Almost all observations from Similajau were from climax forest. Much more information of chevrotain habitat use in areas of sympatry is desirable before firm species-level conclusions can be drawn. T. napu was found typically to range 19 ha in old logged forest and 7 ha in primary forest, this difference again suggesting an association with primary forest (Heydon 1994). 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. 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. Also at this site, Tragulus was more then nine times as abundant in areas of the park with low than with high human population density within 10 km of the park boundary, suggesting limited resilience to human presence, presumably the effects of hunting (O'Brien et al. 2003); note that it is not confirmed that this information refers, even in part, to T. napu. The genus (presumably including this species) was ubiquitous in a study of virgin jungle reserves (VJRs) of West Malaysia which paired each of seven VJRs with a nearby unprotected area with seriously encroached habitat (Laidlaw 2000). The ability of T. napu to use plantations is probably low, because all (the admittedly relatively few) sources agree that it does not persist well in secondary or logged forest. Moreover, Belden Giman (pers. comm. 2008), in extensive observations at Sarawak Planted Forests, Bintulu, Sarawak, has never recorded T. napu in any of the blocks of monoculture plantations there, despite many records of T. kanchil. Given the pace of conversion of forests to plantations across the rane of T. napu, clarification of its degree of plantation use is urgent.

Competition with T. kanchil is not pronounced. In Tabin Wildlife Reserve, Sabah, T. napu was largely confined to mature forest with T. kanchil only in immature forest (Matsubayashi and Sukor 2005). In unlogged forest at Danum Valley, Sabah, T. napu was significantly more common than T. kanchil, but following logging, the numerical dominance of T. napu declined, and in 2–5-year-old regrowth T. kanchil was the commoner species. By 12 years post-logging, T. napu had reasserted its numerical predominance (Heydon 1994).

Tragulus spp. are generally thought to be nocturnal, and at two sites in Borneo, they comprised over half the contacts of spot-lighting surveys (Duckworth 1997), but Matsubayashi and Sukor (2005) found substantial amount of both day- and night-time activity in this species. Duckworth (1997: 186–187) pointed out that most chevrotains spotlit in Similajau National Park, Sarawak, (identified as T. napu) were sitting around resting. The related T. kanchil was considered highly solitary by Matsubayashi et al. 2006) and this may also be somewhat true for T. napu; Duckworth (1995: 177) observed chevrotains identified as T. napu 14 times, of which 12 records involved singles and two involved duos in apparent association.

Collation of information from general sources suggests the following, but the contribution of information from T. nigricans to these conclusions is unknown, so their reliability for T. napu s.s. should be considered preliminary. Females gestate for 152–155 days and give birth to one or, rarely, two young. Young wean at 2–3 months, and reach sexual maturity at 4.5 months. Animals live up to 14 years. The female can be pregnant throughout her adult life, often having just an 85–155 minute 'breather' between giving birth and becoming pregnant again. The young are born fully developed, and can stand within 30 minutes of birth. Mothers nurse their young standing on three legs. They are generally solitary.

Systems
  • Terrestrial
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These animals always live close to water and prefer to be in the undergrowth of dense forests.

Habitat Regions: tropical ; terrestrial

Terrestrial Biomes: forest ; rainforest

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Trophic Strategy

Food Habits

The larger Malay Mouse Deer has a diet of fallen fruit and berries, aquatic plants, leaves, buds, shrubs and grasses.

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Life History and Behavior

Life Expectancy

Lifespan/Longevity

Average lifespan

Status: captivity:
14.0 years.

Average lifespan

Status: captivity:
14.0 years.

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Lifespan, longevity, and ageing

Maximum longevity: 16.7 years (captivity) Observations: One captive specimen lived 16.7 years (Richard Weigl 2005).
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Reproduction

The female spends most of her adult life pregnant. These animals breed year-round with a gestation period of 152 to 155 days and will breed again within a couple of hours after birth. Only one offspring is usually born at a time (twin births are very rare). The offspring are well-developed when born and are able to stand and be fully active 30 minutes after birth. These baby ungulates nurse while standing on three legs. They are weaned at two to three months of age and are sexually mature at four and a half months (living up to sixteen years in captivity).

Breeding season: These chevrotains breed throughout the year.

Range number of offspring: 1 to 2.

Average number of offspring: 1.

Range gestation period: 152 to 155 days.

Range weaning age: 8 to 12 weeks.

Average age at sexual or reproductive maturity (female): 4.5 months.

Average age at sexual or reproductive maturity (male): 4.5 months.

Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 373 g.

Average number of offspring: 1.

Average age at sexual or reproductive maturity (male)

Sex: male:
135 days.

Average age at sexual or reproductive maturity (female)

Sex: female:
137 days.

Parental Investment: precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female)

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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
LC
Least Concern

Red List Criteria

Version
3.1

Year Assessed
2012

Assessor/s
Timmins, R.J., Duckworth, J.W., Steinmetz, R. & Pattanavibool, A.

Reviewer/s
Black-Decima, P.A. & Gonzalez, S.

Contributor/s

Justification
The Greater Oriental Chevrotain is listed as Least Concern because chevrotains remain widespread and at least locally common in the Sundaic region and, at least on Borneo, it appears that this species is resilient to hunting although probably not to habitat degradation. Better data would allow a more confident assessment. Its wide altitudinal tolerance (presumed to be up to 1,000 m asl) means that it has large populations outside the altitude of very rapid forest loss so cannot be listing on population decline rate inferred through Sundaic forest trends. 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 remains the uncertainty over the species relative abundance at various altitudes, in part due to a rather low proportion of modern records of Tragulus from the species range having been identified conclusively to species, however, on the balance of current evidence, this uncertainty is not adjudged sufficient for listing as Data Deficient (if currently assumed altitudinal distribution was shown to be erroneous this might affect Red Listing).

History
  • 2008
    Least Concern
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The subspecies Tragulus napu nigricans is listed with the IUCN as endangered. This subspecies is found on Balabac Island southwest of the Philippines. Otherwise, these animals are threatened because of over-hunting and habitat loss through deforestation.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: least concern

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Population

Population
Greater Oriental Chevrotain populations are not well studied, in part reflecting a general lack of research interest in the genus and in part its almost complete sympatry with the Lesser Oriental Chevrotain, from which separation requires care under field conditions (Duckworth 1997; Matsubayashi and Sukor 2005). It seems to be relatively common on at least Borneo (Payne et al. 1985; Belden Giman pers. comm. 2008). In Thailand, at the northern margin of its range, it is generally rare (Anak Pattanavibool pers. comm. 2008); for example, during the flooding of the Chiew Larn Reservoir (Surat Thani province; about 9°00′N, 98°45′E; 20–130 m asl), only six Greater Chevrotains were ‘rescued’ compared with 172 Lesser Chevrotains (Nakasathien 1989). The genus is commonly camera-trapped and recorded by signs on Sumatra and in West Malaysia (Laidlaw 2000; O'Brien et al. 2003; Kawanishi and Sunquist 2004; Azlan 2006) and in far southern Myanmar (Lynam 2003; the identifications to species should be disregarded). At the Danum Valley, Sabah (East Malaysia), densities were recorded as 32–72 animals per km² in primary habitat; they were more scarce in selectively logged areas, with densities of 6–16 animals per km², indicating a marked decrease in T. napu in selectively logged forest vs unlogged (Heydon and Bulloh 1997, Davies et al. 2001). Because population densities of Southern Red Muntjac Muntiacus muntjak and Sambar Rusa unicolor rose in the logged areas in this same study, the decline in chevrotains presumably reflects habitat factors rather than the secondary complication of logging-induced hunting. Population densities for Tragulus spp. (presumably including this species) in Taman Negara, Malaysia, were taken to be 0.37–0.83 per km² (Kawanishi and Sunquist 2004). Duckworth (1995) considered that the chevrotains demonstrably common at Similajau National Park in 1986 and 1995 were largely or entirely Greater (see Habitat and Ecology).

Population Trend
Decreasing
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Threats

Major Threats
Hunting and habitat loss occur at high levels almost throughout Greater Chevrotain’s range, but the species is said to be relatively resilient. However, few data to support this assessment have been traced, particularly because most key studies have not within the Sundaic region identified chevrotains to species. Thus, while clear that the genus remains widespread and common in the face of these threats, there seems to be little publicly available evidence that T. napu specifically does so, and reasonable evidence that it is not very adaptable to forest degradation (see Habitat and ecology). However, on the assumption that most chevrotains above 100 m asl on Borneo are this species rather than T. kanchil, Borneo at least retains large populations. Greater Oriental Chevrotain is extinct on Singapore (K. Lim pers. comm. 2008), although the relative contributions of hunting versus habitat perturbation are not known.

Poaching pressure in Kerinci-Seblat National Park, Sumatra, among snared ungulates was greatest for muntjacs and lowest for chevrotains, as assessed by diameter of the cable (Linkie et al. 2003). Chevrotains were scarcer in areas of higher human use (and thus hunting) of Bukit Barisan Selatan National Park, Sumatra (O'Brien et al. 2003; see Habitat and ecology). Bennett et al. (2000) profiled the effects of hunting in both Bornean states of Malaysia (Sarawak and Sabah), each with eight study areas, upon chevrotains (not distinguished to species) through a lengthy hunting study in February 1993 to June 1995. They constituted 8–9% of animals killed. No direct or index measure of chevrotain densities was possible at these sites to determine what effects, if any, such heavy hunting was having on chevrotains. Chevrotains are among the most favoured wild meat by inhabitants of the Sarawak Planted Forests area, Bintulu, Sarawak, after Sambar Rusa unicolor and wild pigs Sus (Belden Giman pers. comm. 2008).
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Management

Conservation Actions

Conservation Actions
Hunting and habitat loss occur at high levels almost throughout this species’s range. Adequate legal basis exists in all range states to control both threats (through protected areas and regulations governing wildlife trade and hunting). The chief need is for effective translation of these laws into action. There are no obvious species-specific needs additional to general consolidation of protected areas and enforcement of hunting and wildlife trading laws.

The paucity of Sundaic studies determining chevrotains to species shows admirable caution but hinders assessments of this species’s status. Better data would be useful to confirm the opinion-based conclusion here that this is a resilient species, and to investigate further habitat use, in areas where it overlaps with T. kanchil and in those (probably, primarily at higher altitude) where it does not.
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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Positive

Larger Malay Mouse Deer are often used as a source of food for native people. They also make good pets, for they are easily tamed.

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Wikipedia

Greater mouse-deer

The greater mouse-deer, greater Malay chevrotain or napu (Tragulus napu) is a species of even-toed ungulate in the Tragulidae family. It is found in Sumatra, Borneo and smaller Malaysian and Indonesian islands, and in southern Myanmar, southern Thailand and peninsular Malaysia. It was thought to be regionally extinct in Singapore until it was rediscovered on an offshore island in 2008.[2][3] Reports of its occurrence elsewhere are probably incorrect.[2] Its natural habitat is subtropical or tropical moist lowland forest.

Etymology[edit]

Tragos is Greek for "goat" and –ulus in Latin means "tiny". Napu is a local name, from Malay "Napuh". The name "mouse-deer" refers to its small size and does not imply that it is a true deer. It is called "greater" because it is larger than other Tragulus species.

Evolution[edit]

Morphology[edit]

Although very small for an ungulate, the greater mouse-deer is one of the largest members of its genus. It is rivalled in size by Williamson's mouse-deer. It weighs 5 to 8 kg (11 to 18 lb). Its head-and-body length is 70 to 75 cm (2.30 to 2.46 ft) and its tail length is 8 to 10 cm (3.1 to 3.9 in). Its shoulder height is about 30 to 35 cm (12 to 14 in) It has a small, triangular head with a small, pointed, black nose and large eyes. Its long legs are as thin as a pencil. The hind legs are visibly longer than the front legs. The body is rounded. The fur on the upper part of its body is grey-buff to orange-buff. On the sides, the fur is quite pale, but darker along the midline. It is white underneath, especially on the neck, stomach, chest and chin. The male has neither horns nor antlers, but has small "tusks" – elongated canines in the upper jaws.

Distribution[edit]

Greater mouse-deer are found in Sumatra, Borneo and smaller Malaysian and Indonesian islands, and in southern Myanmar, southern Thailand and peninsular Malaysia. They live near water, in tropical forests and mangrove thickets. They are terrestrial, but spend a lot of time in wet, swampy areas.

Behaviour[edit]

The greater mouse-deer is solitary and nocturnal. It uses small trails through thick brush in the forest. When the male is ready to mate, he rubs a large gland on his lower jaw against the female to determine whether she is ready to mate. If she is not ready, she responds by walking away. The male is very territorial, marking his territory with feces, urine and secretions from the intermandibular gland under the chin. When angry, the male will beat the ground with his hooves at a rate of four times per second. They are rather trusting but delicate animals. They feed on fallen fruits, aquatic plants, buds, leaves, shrubs and grasses.

Reproduction[edit]

Greater mouse-deer breed throughout the year; The female spends most of her adult life pregnant. They usually produce one young per birth, after a gestation of 152–155 days. Newborn animals are well-developed and immediately able to stand; they are fully active after 30 minutes. The young stand on three legs while nursing. Both male and female become mature at age 4½ months. Their life span is up to 14 years.

Economic importance for humans[edit]

The greater mouse-deer is used as a source of food for local people.

Conservation status[edit]

The major threats to T. napu are over-hunting by humans and loss of their habitat[2] through rapid deforestation activity.

References[edit]

  1. ^ Grubb, P. (2005). "Tragulus napu". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. p. 650. ISBN 978-0-8018-8221-0. OCLC 62265494. 
  2. ^ a b c d Timmins, R.J., Duckworth, J.W., Steinmetz, R. & Pattanavibool, A. (2008). Tragulus napu. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 29 March 2009. Database entry includes a brief justification of why this species is of least concern
  3. ^ Chua, M.; N. Sivasothi; Teo. R (2009). "Rediscovery of the greater mousedeer (Tragulus napu) (Mammalia: Artiodactyla: Tragulidae) in Pulau Ubin, Singapore". Nature in Singapore 2: 373–378. 
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