Animal Info - Grizzled Leaf Monkey

(Other Names: Gray, Grizzled or Sunda Island Sureli; Grizzled or Stripe-crested Langur; Javan Grizzled Langur; Java or Javan Leaf Monkey; Langur Gris)

Presbytis comata (P. aygula)

Status: Endangered

1. Profile (Picture)
2. Tidbits
3. Status and Trends (IUCN Status, Countries Where Currently Found, Population Estimates, History of Distribution, Threats and Reasons for Decline)
4. Data on Biology and Ecology (Weight, Habitat, Diet, Behavior, Social Organization, Density and Range)
5. References

Profile

Picture: Grizzled Leaf Monkey (3 Kb JPEG)

The grizzled leaf monkey weighs 6 - 8 kg (13 - 18 lb). It is found in tropical rainforest, where it has been recorded in primary forest and in secondary forest, both at the edges and in the interior. Specific locations include lowland forests, forests on steep slopes and on hills, and in upper montane forests up to 2600 m (8500'). (Nijman & van Balen 1998) The grizzled leaf monkey is folivorous, with one study showing that 62% of its diet comprising young leaves and an additional 6% comprising mature leaves. (Davies & Oates 1994)

All leaf monkeys are diurnal and arboreal forest dwellers (Nowak 1999). The grizzled leaf monkey often occurs in family groupings averaging 6 - 7 individuals (range: 3 - 12 individuals). Some groups have been reported as being monogamous. All-male groups have been observed. Groups are territorial, defending the exclusive use of the majority of their home ranges, although "much overlap" of home ranges has been observed in some cases. (Davies & Oates 1994; Nijman & van Balen 1998)

The grizzled leaf monkey is endemic to the western half of Java, Indonesia. It is threatened by continued habitat loss. Only 4% of its original habitat remained by the late 1980's (Kool 1992). It has declined by at least 50% in the last decade because of habitat destruction (IUCN, cited in Nowak 1999).

Tidbits

*** The unusual nature of the stomach of leaf monkeys and related species probably has a profound influence on their ecology. The stomach is large and multi-chambered, and the forestomach supports bacteria with cellulose-digesting abilities. These monkeys are enabled by their stomach to digest plant fibers, and many include large quantities of foliage in their diet. (Davies & Oates 1994)

Status and Trends

IUCN Status:

1988 - 1994: Endangered
1996 - 2004: Endangered (Criteria: A1c, C2a) (IUCN 2004)

Countries Where the Grizzled Leaf Monkey Is Currently Found:

2004: Occurs in Indonesia (Java) (IUCN 2004).

Population Estimates:

[Note: Figures given are for wild populations only.]

WORLD (Java, Indonesia)
- 1986: 8040 (Kool 1992)
- 1994: 2285 (Nijman & van Balen 1998)
- 1999: Fewer than 2500 mature individuals (IUCN, cited in Nowak 1999)

History of Distribution:

The grizzled leaf monkey is endemic to the western half of Java, Indonesia, and it is found as far east as Mt Lawu on the border with East Java. In 1978 it was reported that the grizzled leaf monkey had a very local distribution and may have been locally abundant (Kool 1992).

Threats and Reasons for Decline:

The grizzled leaf monkey is threatened by continued habitat loss. Only 4% of its original habitat remained by the late 1980's (Kool 1992). It has declined by at least 50% in the last decade because of habitat destruction (IUCN, cited in Nowak 1999).

Data on Biology and Ecology

Weight:

The grizzled leaf monkey weighs 6 - 8 kg (13 - 18 lb).

Habitat:

The grizzled leaf monkey is found in tropical rainforest. It has been recorded in primary forest and in secondary forest, both at the edges and in the interior. Specific locations include lowland forests, forests on steep slopes and on hills, and in upper montane forests up to 2600 m (8500'). (Nijman & van Balen 1998)

The grizzled leaf monkey is found in both the Sundaland Biodiversity Hotspot (Cons. Intl. 2005) and the Mt. Kinabalu Montane & Alpine Scrub & Forest Global 200 Ecoregion. (Olson & Dinerstein 1998, Olson & Dinerstein 1999)

Diet:

In the submontane forests of Kamojong, western Java, the grizzled leaf monkey appeared to be more folivorous than any other member of the genus Presbytis, with 62% of its diet comprising young leaves and an additional 6% comprising mature leaves. Furthermore, its diet is unusual in that 9% was branch-tips, fungi and pseudo bulbs. (Davies & Oates 1994)

Behavior:

All leaf monkeys are diurnal and arboreal forest dwellers (Nowak 1999).

Social Organization:

The grizzled leaf monkey often occurs in family groupings averaging 6 - 7 individuals (range: 3 - 12 individuals). Some groups have been reported as being monogamous. All-male groups have been observed. Groups are territorial, defending the exclusive use of the majority of their home ranges, although "much overlap" of home ranges has been observed in some cases. (Davies & Oates 1994; Nijman & van Balen 1998)

Density and Range:

Density:

4-5 individuals/sq km (10 - 13 individuals/sq mi) (Halimun National Park)

25 individuals/sq km (65 individuals/sq mi) (Mts Gede Pangrango National Park)

28 individuals/sq km (73 individuals/sq mi) (Dieng Mountains)

35 individuals/sq km (91 individuals/sq mi) (Patenggang)

(Nijman & van Balen 1998)

Group Density:

3.5 groups/sq km (9.1 groups/sq mi) (Kamajong)

5 groups/sq km (13 groups/sq mi) (Patenggang)

(Davies & Oates 1994)

Home Range:

Avg: 38 hectares (35 - 40 hectares) (avg: 95 acres (88 - 100 acres)) (Kamajong)

14 hectares (35 acres) (Patenggang)

(Davies & Oates 1994)

References

Cons. Intl. 2005, Davies & Oates 1994, IUCN 1994, IUCN 1996, IUCN 2000, IUCN 2003a, IUCN 2004, Kool 1992, Macdonald 1984, Nijman & van Balen 1998, Nowak 1999, Nowak & Paradiso 1983, Olson & Dinerstein 1998, Olson & Dinerstein 1999

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Last modified: March 16, 2005;