Lesser Mouse Deer (Tragulus javanicus)
Tragulus javanicus as here defined is endemic to the
island of Java, Indonesia, according to Meijaard and Groves (2004). The latter
authors did not mention the island of Bali, but a sighting was reported from
Bali Barat National Park, Bali, in a bird watching trip report (Bird quest
2006). The genus was not listed for Bali in the exhaustive reviews of Chasen
(1940; of the genus) or Meijaard (2003; mammals of Indonesian islands), nor by
Grubb (2005). Given the live-animal trade in the genus on Java, further records
are needed to confirm whether or not there is a native population of the genus
on Bali. If there is, bio geographic considerations suggest it would be most
closely related to the Javan population and quite probably conspecific.
Hoogerwerf (1970) wrote that "in Java T. javanicus was encountered in all provinces, fairly intensively distributed from sea-level to high in the mountains". Present-day occurrence in East Java is questionable: S. Hedges, M. Tyson and E. Meijaard (pers. comm. 2008) know of no certain records (as distinct from listings in collation documents which do not cite information to primary source) from areas like Baluran or Alas Purwo national parks, despite high survey effort during 1991–2000.
Meijaard and Groves (2004) gave only one specific locality for the species: Cheribon (= Cirebon) on the north coast of West Java Province, which is the type locality of T. j. pelandoc Dobroruka, 1967. Dobroruka (1967) also mentioned the western part of Java, to the southern coast, for what he called T. j. focalinus (which is T. javanicus s .s.). Meijaard and Groves (2004) did not list the localities for the many specimens they examined. Dobroruka (1967) and Van Dort (1986) both discuss variation within Javan chevrotains; neither has yet been checked for specific localities. More recent localities, although not of specimen records, include: Gunung Halimun (reportedly camera-trapped some time before 2003 [Suyanto 2003], but the photograph is not reproduced in the appendix and a painting is used for the species instead); Ujung Kulon (1991–1993; van Schaik and Griffiths 1996; C.P. Groves pers. comm. 2008), and the Dieng Plateau (during 1999–2000; V. Nijman pers. comm. 2008). There has been no collation of records from the various surveys over the last 20 years or so, and some observers no doubt are aware of other localities. Dubious sighting have been recorded in southern Thailand but these could be erroneous
Indonesia (Jawa, Kalimantan, Sumatera); Malaysia (Peninsular Malaysia, Sabah, Sarawak)
There appears to have been no field study specifically of
chevrotains on Java but current wildlife surveyors agree that they are rarely
seen compared with results from similar styles of observation in Kalimantan (S.
van Balen, V. Nijman, E. Meijaard, M. Tyson and S. Hedges, all pers. comm.
2008). Even Hoogerwerf (1970), who clearly found the species with some
regularity (explicitly not daily, but enough for him to learn its calls and
thereby establish dates of a probable mating season), complained that “it is
particularly difficult to obtain any insight into the situation of this species
in Java”, but concluded that “it is improbable that the species is in danger of
extinction”. The basis for an unattributed statement in Whitten et al. (1996),
that “it is still numerous and can be seen easily in many areas such as the
tourist park part of Pangarandaran Nature Reserve” is unclear. The genus was
recorded at five of ten sites on the Dieng Plateau surveyed in 1999–2000, but
mostly only through single observations (V. Nijman pers. comm. 2008). S. van
Balen (pers. comm. 2008) points out that in Java the genus seems very shy
(compared with animals in Malaysia and Kalimantan), so most records come as
footprints. This contrasts with the assignment by Hoogerwerf (1970) that the
genus was common and widespread. It is therefore quite plausible that a major
decline has taken place, although other explanations remain to be explored which
could have bolstered Hoogerwerf’s sighting rates, such as his having a dog with
him which flushed the chevrotains, or his spending a lot of time in the species'
favoured microhabitats. Specifically, neither M. Tyson nor S. Hedges (pers.
comm. 2008) saw chevrotains during a rhinoceros survey in Ujung Kulon in 1992,
whereas this was Hoogerwerf’s (1970) main site in assessing the species as
relatively common and readily found. It was camera-trapped there five times
during 1991–1993 (van Schaik and Griffiths 1996), a rate comparable with that of
many other species in the study and certainly not suggesting out-and-out rarity.
Very recently, numbers in trade in Java have dropped sharply in most cities, and
it is plausible that this reflects increasing difficulty in procuring the animal
(G. Semiadi pers. comm. 2008).
Population Trend: Unknown
Habitat and Ecology:
Hoogerwerf (1970) wrote of chevrotains on Java occurring "from
sea-level to high in the mountains". In the Dieng plateau area, V. Nijman (pers.
comm. 2008) found them only a few times in the lowlands (400–700 m asl), where
most survey took place, and had no records from above about 1,500 m asl. They
have been found on Gunung Gede–Pangangro up to about 1,600 m asl (V. Nijman
pers. comm. 2008). Hoogerwerf’s (1970) description of favoured habitats on Java
suggests that chevrotains there might be an 'edge' species, certainly seeming to
prefer areas with thick understory vegetation, such as that along riverbanks.
This would not be unusual within the genus (see other Tragulus accounts).
Java has highly fragmented natural habitats and has done for
centuries, reflecting longstanding high human population densities. Many
protected areas were established during the Dutch colonial period but from
independence up until the 1970s they were largely under-funded and neglected.
After hosting the World Parks Conference in 1982, the Indonesian government
gazetted a swathe of national parks and more structured conservation planning
began, funded by the World Bank and other donors. The focus was largely on the
'multi-function' national parks and much money was spent on infrastructure, some
staff training and increased personnel. The 'lesser' protected areas such as
"game reserves" and "nature reserves" still had few staff and resources, and
that has continued to the present. During the 1980s to the mid 1990s, guns were
tightly controlled and the military and police were feared and respected.
However, the strong culture of caged bird keeping meant that hunting, including
that within protected areas, was primarily for birds and some small game,
through various forms of trapping, including snaring; this latter could well
have included chevrotains. There was some habitat loss from protected areas
through illegal logging, agricultural encroachment and other offtake, but the
national parks of Java remained remarkably intact for much of this period.
Socio-political changes from 1997 led to a reduction in the respect for the
police and military and the rise of a viewpoint that protected areas were the
peoples' resources and would therefore benefit from decentralised management (S.
Hedges and M. Tyson pers. comm. 2008). This policy change, which risked a
‘tragedy of the commons’, has indeed led to increased destruction and poaching
in the past decade. There is some evidence that species readily uses edge and
secondary vegetation, meaning that effects of forest encroachment will be less
serious than for old-growth forest obligates. Moreover, chevrotains already
seemed rare for surveyors operating in the early–mid 1990s, when habitats had
been relatively stable since 1970s or early 1980s. For any decline which may
have occurred in the 1980s and early–mid 1990s, therefore, habitat factors are
an unlikely driver. Chevrotains occur regularly in markets in towns such as
Jakarta, Surabaya, Yogyakarta, and Malang, but often they are cramped in small
cages, and can therefore be overlooked, and may even be more common than
observations suggest; numbers in trade are surprisingly high given the small
numbers to be seen in the field nowadays (V. Nijman pers. comm. 2008). They have
been traded at high levels for many decades: Hoogerwerf (1970) wrote of
“numerous reports of mouse deer being regularly trapped and offered for sale
alive” in Java. They are hunted and traded both for pets and as wild meat (S.
Hedges pers. comm. 2008). Numbers passing through markets in Jakarta, Bogor, and
Sukabumi have recently declined sharply, perhaps because of tightened control by
the forest police in those markets; but there is the possibility that falling
trade might indicate, at least in part, increasing difficulty to catch the
animal and thus a decline in populations. In the Malang area, it is still
“relatively easy” to procure one, although it is “getting time consuming” (G.
Semiadi pers. comm. 2008). Hunting is probably largely with snares; dogs are
also likely to be a serious threat (M. Tyson pers. comm. 2008). They are
vulnerable to active hunting at night through a propensity to freeze when spot
lit. However, the effects of these comparably high hunting levels on the genus
in Java have not been studied empirically. The continued presence of many
animals in markets suggests that significant populations remain somewhere on
Java (assuming that the animals are not now imports from elsewhere in
Indonesia), and thus that a major decline may not have occurred, despite current
indications. A comparable situation was found with in ornate squirrel
Callosciurus inornatus in Lao PDR, when extensive 1990s surveys found few
animals in the field, in contrast with historic statements of abundance and
ongoing substantial numbers being traded in fresh meat markets. This led to
conservation concern for the species (e.g. Duckworth et al. 1999); but later
field survey of degraded and edge areas found out that the species was indeed
common and evidently a species associated with degraded areas, and had hence
been severely under-recorded by the 1990s surveys (Timmins and Duckworth in
Chevrotains on Java occur in some protected areas, e.g. Ujung Kulon (Hoogerwerf 1970; van Schaik and Griffiths 1996) and were earlier said to “occur in all game sanctuaries in Java and in most of the nature reserves established on that island...." (Hoogerwerf 1970). The species has been officially protected since 1931, yet it is still hunted. The taxonomic revision of Meijaard and Groves (2004) means that T. javanicus is endemic to Java, and, if it occurs, Bali. There are fair indications of a decline, perhaps a major one, and thus this newly-revealed endemic species should be swiftly removed from the anonymity in which it has lain for decades. An urgent first step is a collation of existing information, because it is possible that many more records exist than were traced during the preparation of this assessment. This should include trawling likely observers and examination of collections not covered by Meijaard and Groves (2004). If insufficient number of specimens are found to clarify the number of taxa on Java, more should be obtained. Some may come from markets but, because of the pre-eminence of locality in determining systematics among very similar taxa (e.g. Groves in press: discussion under Wapiti group), specimens of known locality origin must form the basis of analysis. Whatever the number of species on Java, the difference in sighting rate between Hoogerwerf (1970) and observers from the 1990s onwards is suggestive of a major decline, although other explanations are possible (see Population and Threats). Current status needs to be clarified through specific surveys for the genus (camera-trapping, but undertaken in a way more suitable for smaller species than is usual, spotlighting, and hunting surveys may all play a role). Surveys must take care to investigate secondary and edge areas which are often eschewed by general wildlife surveys in favour of the less encroached areas.