Topic
Trachypithecus laotum
About: Trachypithecus laotum is a research topic. Over the lifetime, 8 publications have been published within this topic receiving 125 citations.
Papers
TL;DR: The use of a laboratory-based method to measure the mechanical properties of foods selected and processed by 4 captive species of Southeast Asian Colobinae and the findings suggest that Trachypithecus spp.
Abstract: Colobines are similar in their exploitation of a high percentage of leaf matter. However, this observation obfuscates interesting differences among genera of Southeast Asian colobines in morphology and behavior that may be reflected in the degree to which they rely on mastication or gut volume and gut retention time when ingesting and digesting leaves. We detail the use of a laboratory-based method to measure the mechanical properties of foods selected and processed by 4 captive species of Southeast Asian Colobinae —Pygathrix nemaeus, Pygathrix cinerea, Trachypithecus delacouri, and Trachypithecus laotum hatinhensis— at the Endangered Primate Rescue Center (EPRC), Vietnam. We also detail a field method that quantifies chewing rates and chewing behavior via a consumer-grade video camera and laptop computer. Observations in the captive setting permit a degree of experimental control that is not possible in the wild, and the location of the EPRC in the primates’ habitat country permitted us to provide leaves that they encounter and eat in the wild. We collected toughness data with a portable tester designed by Lucas et al. The average toughness of selected leaves does not differ among the taxa, nor does the length of time spent chewing foods. However, there are differences in feeding rate, with Trachypithecus spp. chewing foods twice as fast as Pygathrix spp. Our findings suggest that Trachypithecus spp. emphasize comminution of food by mastication, while Pygathrix spp. emphasize the comminution of leaf matter in the stomach. The hypothesis is supported by data on molar size, gut mass, and gut morphology. We provide new insights into dietary variation among primate species and detail methods that are typically conducted only in a laboratory setting. We augment the findings with additional data on activity, feeding rates, and tooth morphology.
59 citations
TL;DR: A detailed examination of the distribution of the Laotum taxon and its conservation status is presented in this article, with a focus on the Lao leaf monkeys (Trachypithecus (francoisi) laotum).
Abstract: Lao leaf monkeys (Trachypithecus (francoisi) laotum) are endemic to a small area of central and, marginally, north Lao. They are known from a few, mostly vague, historical records. We here present a detailed examination of the distribution of this little-known taxon and discuss its conservation status. Surveys since 1992 show its range to be centered upon the karst-dominated Phou Hin Poun National Protected Area (NPA), Nam Sanam Provincial Protected Area, and the southern part of Nam Kading NPA. The known range encompasses <2000 km², within which occurrence is patchy, reflecting habitat availability. The taxonomic identity of leaf monkeys plausibly of this group reported to the north of this area is not known. In the south of Phou Hin Poun NPA, village reports that the monkeys have black heads are corroborated by the few sightings; their taxonomic relationship with typical Trachypithecus laotum is unknown. In the mid–late 1990s large populations remained and individuals were easily seen. There is no apparent large-scale threat to their habitat. There has been no significant reassessment of status since the late 1990s, nor is there any active conservation action in place. Although the monkeys are to a significant extent protected by the arduous terrain, this cannot be relied upon indefinitely: Trade-directed hunting, although apparently limited in the 1990s, is a potential threat that could cause rapid population declines. Local traditions offer significant starting points for conserving these monkeys.
13 citations
TL;DR: The Hatinh langur, Trachypithecus laotum hatinhensis (Dao, 1970), is one of the many Vietnamese primates on the brink of extinction due to hunting and the loss of its natural habitat as mentioned in this paper.
Abstract: The Hatinh langur, Trachypithecus laotum hatinhensis (Dao, 1970), is one of the many Vietnamese primates on the brink of extinction due to hunting and the loss of its natural habitat. This black langur, distinguished by its white moustache and sideburns that extend behind the ears to the nape, inhabits the limestone forests of the Central Annamite Mountains. The Hatinh langur is diurnal and largely arboreal, and group sizes are 15 or more. Here we report on surveys carried out in 1998–1999 in Quang Binh Province to determine the population status of T. laotum hatinhensis. In Vietnam, it occurs only in the limestone areas of five districts in the Quang Binh Province and Huong Hoa District of Quang Tri Province. The most important population is in the Phong Nha–Ke Bang National Park of Quang Binh Province; the only Vietnamese protected area where it is known to occur. Some observations on the species ecology and behavior are also included.
11 citations
TL;DR: Trachypithecus delacouri lives among limestone cliffs and consumes the leaves of a broad spectrum of plant species but its choice of food items tends to be based on the chemical makeup of the plant phenophases with protein content the strongest predictor of leaf selection.
Abstract: Trachypithecus delacouri (Osgood, 1932), commonly called Delacour's langur or lutung, is a black and white lutung (leaf monkey) endemic to northern Vietnam. It is a diurnal and primarily arboreal species, but spends more time on the ground than other species of Trachypithecus. T. delacouri lives among limestone cliffs and consumes the leaves of a broad spectrum of plant species but its choice of food items tends to be based on the chemical makeup of the plant phenophases with protein content the strongest predictor of leaf selection. Territorial, but with overlapping territories, it usually lives in single-male–multifemale groups of 5–30, although 2 adult males may be present. With a declining population perhaps as low as 200 individuals in 17 or fewer isolated populations, it is 1 of the world's most endangered primates.
8 citations
1 Jan 2008
TL;DR: In this paper, a semi-wild enclosure for Hatinh langurs from the Endangered Primate Rescue Center (EPRC) in central Vietnam was built and two groups from the EPRC were transferred to the Frankfurt Zoological Society.
Abstract: Summary In 2005 the Frankfurt Zoological Society in cooperation with the Cologne Zoo launched a reintroduction program for two endangered primate species, the Hatinh langur ( Trachypithecus laotum hatinhensis ) and red-shanked douc langur ( Pygathrix nemaeus ) in the Phong Nha ‐ Ke Bang National Park in central Vietnam. As a first step, a semi-wild enclosure was built and in early September 2007 two groups of Hatinh langurs from the Endangered Primate Rescue Center were transferred. All individuals were equipped with radio collars and continuously monitored over a periodofnineweeks.Thelangurssettled-inwellandrapidlyexploredthewholeenclosure.Original group composition was not maintained, but the langurs finally merged into one group. While during the first half of the study, observation conditions were limited as animals were hiding under dense liana covers, later on the langurs gradually exposed themselves in more open areas, allowing extended data sampling periods. Follow-up studies are recommended.
5 citations
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| Year | Papers |
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| 2021 | 1 |
| 2011 | 2 |
| 2008 | 3 |
| 2006 | 1 |
| 2004 | 1 |