Wildlife of Lao PDR: 1999 Status Report - IUCN

Wildlife of Lao PDR: 1999 Status Report
another (RB; Plate 13). The supposition that S. f. delacouri
could possibly also extend into north-east Lao PDR from
adjacent Vietnam has not been confirmed by field work.
Black-coloured langurs are reported from several areas within
which there has been no recent fieldwork, e.g. near Nam
Chouan PNBCA (Robichaud 1998d); limestone areas south
and west of Hin Namno NBCA; and the limestone northeast
of Nam Theun north of Ban Lak (20), and between Nakai-
Nam Theun NBCA, Nam Kading NBCA and Nam Chouan
PNBCA (RJTim). Detailed villagers’ descriptions from some
of these areas suggest that as yet undocumented forms may
exist. The general distribution of positive responses during
1988-1993 village interviews accords closely with the above
information (Annex 5). Although Francois’s Langurs are shot
opportunistically for food, the inaccessibility of their habitat
and the sheer size of these rugged areas means that most
populations may still be healthy. In neighbouring Vietnam,
however, several forms face imminent extinction (Nadler
1996a, Duckworth and Walston in prep.) indicating that there
is no room for complacency in Lao PDR. Taxonomic issues:
This nominal species comprises seven phenotypically distinct
forms and there is little consensus on the relationships
between them and on how many should be viewed as full
species (contrast Corbet and Hill 1992, Brandon-Jones 1995
and Rowe 1996). For conservation planning purposes, however,
two forms occurring in Lao PDR (laotum and
hatinhensis) should be treated as separate units (see Eudey
1987). The taxonomic status of the black-headed form is
unclear. A black-headed skin of unknown provenance was
named by Brandon-Jones (1995) as (S. f.) ebenus, and Nadler
(1996b) hypothesised that this form also occurred in Lao PDR.
It is unclear whether the black-headed animals in Lao PDR
are the same as (S. f.) ebenus, and whether, if so, the latter is
a discrete taxon. Were it confirmed to occur, S. f. delacouri
would also constitute an individual unit, as would any as-yet
undescribed form.
• Semnopithecus cristatus (= Presbytis cristata M2, M3, M4 ; =
Trachypithecus cristatus M6, M7 ) Silvered Langur (= Silvered
Leaf Monkey M4, M5 ). Conservation Significance: Globally
Near-Threatened; At Risk in Lao PDR; CITES Appendix II.
Documented Range and Habitat: Centre (potentially,
Boonratana 1998b), south M8 . Evergreen forest, particularly
along watercourses, including in areas otherwise dominated
by deciduous forest. Status Information: See below. Silvered
Langur is widespread in south Lao PDR, where it has been
found in at least seven survey areas (Table 12). Recent villager
reports of grey langurs from two sites north of the confirmed
range, Dong Phou Vieng and Phou Xang He NBCAs
(Steinmetz 1998a, Boonratana 1998b; RS, RB) are perhaps
more likely to be this species than Phayre’s. Silvered Langurs
provisionally identified in 1998 in Nam Phoun NBCA
(Boonratana 1998b; RB) would represent a large northward
extension of known range, as the outlying populations mapped
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in the Assam / Myanmar area for this species in Corbet and
Hill (1992) are both mistakes (D. Brandon-Jones in litt. 1999).
Historical specimens come from Ban Phone on the Bolaven
Plateau and Xe Don (the former as Pithecus pyrrhus
argenteus; Osgood 1932, Fooden 1976). Taxonomic issues:
The taxonomic contents of S. cristatus and S. phayrei are
unclear (Lekagul and McNeely 1977: 276; D. Brandon-Jones
verbally 1998). The arrangement here, of a largely southern
form (assigned to S. cristatus) separated by a large area (where
no form of this group is common) from a largely northern
one (assigned to S. phayrei), is provisional. C. P. Groves (in
litt. 1999) assigns all the Indochinese animals of the southern
form to S. germaini, reserving S. cristatus for Sundaic
animals. Dao Van Tien (1977) described Presbytis cristata
caudalis from two zoo specimens. Their origin is unknown,
but it could have been Lao PDR.
• Semnopithecus phayrei (= Presbytis phayrei M2, M4 ; =
Trachypithecus phayrei M6, M7 ) Phayre’s Langur (= Phayre’s
Leaf Monkey M4, M5 ). Conservation Significance: Data Deficient
(Global); At Risk in Lao PDR; CITES Appendix II.
Documented Range and Habitat: North M15 , centre
(provisionally M13 ). Various forest types, including degraded
areas; sometimes on limestone. Occurs from the Mekong
valley up to at least 800 m. Status Information: See below.
There are recent records from only three survey areas. In
five others, grey langurs seen and/or reported by villagers
were assigned to this species on the basis of range (Table
12). These are fewer confirmed records than of any other
monkey species in Lao PDR, despite its wide range. Furthermore,
several areas surveyed within the species’s range lack
even provisional records. In marked contrast to Douc and
Francois’s Langurs, Phayre’s has not been found commonly
in any single area, although it may be locally numerous in
Phou Dendin NBCA (Plate 13). Historically the species was
found in Khet Dong Hieng (Vientiane Province),
Xiangkhouang, Muang Mo, Ban Muangyo and
Louangphabang (Delacour 1940, Fooden 1976); Osgood
(1932) referred to some of these (as well as some from southern
Indochina now considered as S. cristatus) as Pithecus
pyrrhus argenteus (now taken as a synonym of S. p.
crepusculus). Taxonomic issues: See note under S. cristatus.
• Pygathrix nemaeus Douc Langur (= Douc Monkey M7 );
(separated as Pygathrix nemaeus Red-shanked Douc Langur
by various sources). Conservation Significance: Globally
Threatened - Endangered; At Risk in Lao PDR; CITES
Appendix I. Endemic to parts of Lao PDR, Vietnam and Cambodia;
occurs only east of the Mekong (Corbet and Hill 1992,
Nadler 1997). Documented Range and Habitat: North
(Timmins and Duckworth in press), centre M8 , south M8 . Evergreen
forest from the Mekong valley to at least 1200 m,
including on limestone. Absent from most areas which are
degraded, fragmented and/or largely deciduous (Timmins and