Langur Research Articles

Low Genetic Diversity and Strong Geographical Structure of the Critically Endangered White-Headed Langur (Trachypithecus leucocephalus) Inferred from Mitochondrial DNA Control Region Sequences.

Many Asian colobine monkey species are suffering from habitat destruction and population size decline. There is a great need to understand their genetic diversity, population structure and demographic history for effective species conservation. The white-headed langur (Trachypithecus leucocephalus) is a Critically Endangered colobine species endemic to the limestone karst forests in southwestern China. We analyzed the mitochondrial DNA (mtDNA) control region sequences of 390 fecal samples from 40 social groups across the main distribution areas, which represented one-third of the total extant population. Only nine haplotypes and 10 polymorphic sites were identified, indicating remarkably low genetic diversity in the species. Using a subset of 77 samples from different individuals, we evaluated genetic variation, population structure, and population demographic history. We found very low values of haplotype diversity (h = 0.570 ± 0.056) and nucleotide diversity (π = 0.00323 ± 0.00044) in the hypervariable region I (HVRI) of the mtDNA control region. Distribution of haplotypes displayed marked geographical pattern, with one population (Chongzuo, CZ) showing a complete lack of genetic diversity (having only one haplotype), whereas the other population (Fusui, FS) having all nine haplotypes. We detected strong population genetic structure among habit patches (Φ ST = 0.375, P < 0.001). In addition, the Mantel test showed a significant correlation between the pairwise genetic distances and geographical distances among social groups in FS (correlation coefficient = 0.267, P = 0.003), indicting isolation-by-distance pattern of genetic divergence in the mtDNA sequences. Analyses of demographic history suggested an overall stable historical population size and modest population expansion in the last 2,000 years. Our results indicate different genetic diversity and possibly distinct population history for different local populations, and suggest that CZ and FS should be considered as one evolutionarily significant unit (ESU) and two management units (MUs) pending further investigation using nuclear markers.

First discovery of colobine fossils from the Late Miocene/Early Pliocene in central Myanmar

Here we report two kinds of colobine fossils discovered from the latest Miocene/Early Pliocene Irrawaddy sediments of the Chaingzauk area, central Myanmar. A left mandibular corpus fragment preserving M1–3 is named as a new genus and species, Myanmarcolobus yawensis. Isolated upper (M1?) and lower (M2) molars are tentatively identified as Colobinae gen. et sp. indet. Although both forms are medium-sized colobines, they are quite different from each other in M2 morphology. The isolated teeth of the latter show typical colobine-type features, so it is difficult to identify their taxonomic position, whereas lower molars of Myanmarcolobus have unique features, such as a trapezoid-shaped long median lingual notch, a deeply concave median buccal cleft, a strongly developed mesiobuccal notch, and rather obliquely running transverse lophids. Compared with fossil and living Eurasian colobine genera, Myanmarcolobus is most similar in lower molar morphology to the Pliocene Dolichopithecus of Europe rather than to any Asian forms. In Dolichopithecus, however, the tooth size is much larger and the median lingual notch is mesiodistally much shorter than that of Myanmarcolobus. The discovery of Myanmarcolobus in central Myanmar is the oldest fossil record in Southeast Asia not only of colobine but also of cercopithecid monkeys and raises many questions regarding the evolutionary history of Asian colobine monkeys.

The Hand of Cercopithecoides williamsi (Mammalia, Primates): Earliest Evidence for Thumb Reduction among Colobine Monkeys.

Thumb reduction is among the most important features distinguishing the African and Asian colobines from each other and from other Old World monkeys. In this study we demonstrate that the partial skeleton KNM-ER 4420 from Koobi Fora, Kenya, dated to 1.9 Ma and assigned to the Plio-Pleistocene colobine species Cercopithecoides williamsi, shows marked reduction of its first metacarpal relative to the medial metacarpals. Thus, KNM-ER 4420 is the first documented occurrence of cercopithecid pollical reduction in the fossil record. In the size of its first metacarpal relative to the medial metacarpals, C. williamsi is similar to extant African colobines, but different from cercopithecines, extant Asian colobines and the Late Miocene colobines Microcolobus and Mesopithecus. This feature clearly links the genus Cercopithecoides with the extant African colobine clade and makes it the first definitive African colobine in the fossil record. The postcranial adaptations to terrestriality in Cercopithecoides are most likely secondary, while ancestral colobinans (and colobines) were arboreal. Finally, the absence of any evidence for pollical reduction in Mesopithecus implies either independent thumb reduction in African and Asian colobines or multiple colobine dispersal events out of Africa. Based on the available evidence, we consider the first scenario more likely.

Feeding and nesting ecology of Indian giant squirrel Ratufa indica (erxleben,1777) in Kuldiha wildlife sanctuary, Balasore, Odisha, India and its conservation.

The Indian Giant Squirrel (IGS) Ratufa indica, an endemic species to India is widely distributed in the peninsular India from the ever green to mixed moist and dry deciduous forest of Western and Eastern Ghats and central Indian Hills. We studied its activity pattern, feeding and nesting behavior in the selected sites of Kuldiha Wildlife Sanctuary during 2008-2012. A total of 8640 minutes of observation spent using Focal Animal Sampling Method to study activity budget, feeding and nesting patterns of IGS reveals that the animal spends maximum time in feeding (58%) followed by resting (34%), movement (6.8%) and other activity (1.2%) of its daily activity. The diet of IGS constitutes seed, bark, petiole, leaf, flower and fruit from 23 species of plants belonging to 15 families with Terminalia tomentosa as the most significant contributor i.e20.04% to the diet of the animal followed by Tamarindus indica (17.1%) and Mangifera indica (13.1%) . Seeds formed the highest bulk of the IGH diet i.e. 29.4% followed by leaf (18.2%), flower (12.8%), fruit (11.7%) and bark (11.3%). Nesting characteristics assessed through 44 nests shows that IGS uses 15 species of plant belonging to 14 families with highest preference to Shorea robusta (20%) followed by Schleicheria oleosa (17.5%) and Terminalia tomentosa (15.0%). Nest trees are taller in height, larger in GBH and canopy contiguity which are attributed to easy movement and better protection and escape from predators like Langur and Rhesus monkey. Habitat restoration, reduction in anthropogenic pressure and systematic scientific research are measures suggested for management and sustainable conservation of Indian Giant Squirrel in the study area.

Different Roles of Seeds and Young Leaves in the Diet of Red Leaf Monkeys (Presbytis rubicunda): Comparisons of Availability, Nutritional Properties, and Associated Feeding Behavior

It is important to clarify the roles of different types of foods in the diet of primates that switch to other foods as preferred food items become rare. Using red leaf monkeys (Presbytis rubicunda) in Danum Valley, Borneo, as an example, we compare the availability and nutritional properties of young leaves and seeds, as well as the monkeys’ feeding behavior, to examine food choice and how such choices may affect their competitive regime. Over 21 mo, the number of flushing trees was larger than that of fruiting trees. When we compared nutritional content for all species, including those that the monkeys did not eat, seeds contained more lipids than young leaves but young leaves did not have any nutritional advantage over seeds. However, when we compared only food species, young leaves contained more crude ash than seeds. The proportion of food species to the total available species was significantly higher for seeds than for young leaves. In addition, red leaf monkeys selected young leaf species with higher digestible protein, but no nutritional component predicted seed selection. Young leaves are nutritionally low-quality in general, so monkeys may need to select species with higher quality leaves. However, seeds generally have high-quality nutritional values, so it may not be necessary to select species with marginally higher quality. When eating seeds, the number of individuals eating in the patch was larger, and this feeding in the patch tended to last longer than when monkeys ate young leaves, suggesting more intense feeding competition when feeding on seeds. In conclusion, seeds and young leaves have different nutritional advantages as foods and red leaf monkeys were more selective when eating young leaves than when eating seeds.

RECONSTRUCTING THE DIET AND PALEOECOLOGY OF PLIO-PLEISTOCENE CERCOPITHECOIDES WILLIAMSI FROM STERKFONTEIN, SOUTH AFRICA

ABSTRACT The Plio-Pleistocene cave site of Sterkfontein has yielded the remains of Cercopithecoides williamsi, a colobine monkey reconstructed as a terrestrial folivore given its dental morphology, heavily worn teeth and robustly built postcranial skeleton. To address the validity of these dietary and habitat inferences, patterns of dental microwear obtained from low-magnification stereomicroscopy for C. williamsi specimens from Sterkfontein Member 4 (n = 13) are compared to a broad comparative sample of extant primates, including Cebus apella (n = 10), Colobus polykomos, (n = 6), Papio anubis (n = 13), and Papio ursinus (n = 39) as well as extinct Parapapio broomi (n = 12) from Sterkfontein Member 4 and Theropithecus oswaldi danieli (n = 6) from Swartkrans Member 1. Cercopithecoides williamsi exhibits numerous large pits and puncture pits, and few fine scratches. When diet is considered, C. williamsi is closely associated with C. polykomos and C. apella, suggesting folivorous resources and ...

Multilocus typing of Cryptosporidium spp. and Giardia duodenalis from non-human primates in China

Non-human primates (NHPs) are commonly infected with Cryptosporidium spp. and Giardia duodenalis. However, molecular characterisation of these pathogens from NHPs remains scarce. In this study, 2,660 specimens from 26 NHP species in China were examined and characterised by PCR amplification of 18S rRNA, 70kDa heat shock protein (hsp70) and 60kDa glycoprotein (gp60) gene loci for Cryptosporidium; and 1,386 of the specimens by ssrRNA, triosephosphate isomerase (tpi) and glutamate dehydrogenase (gdh) gene loci for Giardia. Cryptosporidium was detected in 0.7% (19/2660) specimens of four NHP species including rhesus macaques (0.7%), cynomolgus monkeys (1.0%), slow lorises (10.0%) and Francois’ leaf monkeys (6.7%), belonging to Cryptosporidium hominis (14/19) and Cryptosporidium muris (5/19). Two C. hominis gp60 subtypes, IbA12G3 and IiA17 were observed. Based on the tpi locus, G. duodenalis was identified in 2.2% (30/1,386) of specimens including 2.1% in rhesus macaques, 33.3% in Japanese macaques, 16.7% in Assam macaques, 0.7% in white-headed langurs, 1.6% in cynomolgus monkeys and 16.7% in olive baboons. Sequence analysis of the three targets indicated that all of the Giardia-positive specimens belonged to the zoonotic assemblage B. Highest sequence polymorphism was observed at the tpi locus, including 11 subtypes: three known and eight new ones. Phylogenetic analysis of the subtypes showed that most of them were close to the so-called subtype BIV. Intragenotypic variations at the gdh locus revealed six types of sequences (three known and three new), all of which belonged to so-called subtype BIV. Three specimens had co-infection with C. hominis (IbA12G3) and G. duodenalis (BIV). The presence of zoonotic genotypes and subtypes of Cryptosporidium spp. and G. duodenalis in NHPs suggests that these animals can potentially contribute to the transmission of human cryptosporidiosis and giardiasis.

Molecules support morphology: species status of South Indian populations of the widely distributed Hanuman langur

The taxonomy of the Hanuman langur (Semnopithecus spp.), a widely distributed Asian colobine monkey, has been in a flux for a long time due to much disagreement between various classification schemes. However, results from a recent field-based morphological study were consistent with Hill's (Ceylon J Sci 21:277-305, 1939) species level classification scheme. Here we tested the validity of S. hypoleucos and S. priam, the two South Indian species recognized by Hill. To this end, one mitochondrial and four nuclear markers were sequenced from over 72 non-invasive samples of Hanuman langurs and S. johnii collected from across India. The molecular data were subjected to various tree building methods. The nuclear data was also used in a Bayesian structure analysis and to determine the genealogical sorting index of each hypothesized species. Results from nuclear data suggest that the South Indian population of Hanuman langur consists of two units that correspond to the species recognized by Hill. However in the mitochondrial tree S. johnii and S. priam were polyphyletic probably due to retention of ancestral polymorphism and/or low levels of hybridization. Implications of these results on conservation of Hanuman langurs are also discussed.

Erratum to: Fallback Foods of Red Leaf Monkeys (Presbytis rubicunda) in Danum Valley, Borneo

In the published paper, the number of fruiting/flushing trees was erroneously scored as zero for February–May 2008, rather than as missing data due to the incomplete phenology recording. The authors apologize sincerely for this error. Following reanalysis without these incorrect data, we found that both fruiting and flushing phenology affect seasonal variation in the diet, rather than fruiting phenology alone. The final conclusion is unchanged. The following changes correct this error, with new text in bold: Page 325: Methods subsection “Phenology” should read: We used data on monthly tree phenology accumulated by the Danum Valley Field Centre since July 2004, using the same plot set as Norhayati (2001) and the same protocol as the census conducted from August 1997 until December 2000 (Wong et al. 2005). They monitored flushing, flowering, and fruiting activities of 511–533 identified trees of ≥10 cm diameter at breast height (DBH) every month. Plots were situated in primary forest, including the home range of the study group. The monitored area consisted of five transects, each 20 × 100 m, placed every 400 m along the 2-km trail. We did not use data for February–May 2008 because data on species composition in these months were incomplete. Page 326: paragraph 2 of Methods subsection “Data Analysis” should read: We examined the effect of the proportion of fruiting and flushing trees in the phenology survey on the proportion of feeding time of the particular food category Int J Primatol (2014) 35:1077–1082 DOI 10.1007/s10764-014-9785-1

The role of ecological opportunity in shaping disparate diversification trajectories in a bicontinental primate radiation

Exceptional species and phenotypic diversity commonly are attributed to ecological opportunity (EO). The conventional EO model predicts that rates of lineage diversification and phenotypic evolution are elevated early in a radiation only to decline later in response to niche availability. Foregut fermentation is hypothesized to be a key innovation that allowed colobine monkeys (subfamily Colobinae), the only primates with this trait, to successfully colonize folivore adaptive zones unavailable to other herbivorous species. Therefore, diversification rates also are expected to be strongly linked with the evolution of traits related to folivory in these monkeys. Using dated molecular phylogenies and a dataset of feeding morphology, I test predictions of the EO model to evaluate the role of EO conferred by foregut fermentation in shaping the African and Asian colobine radiations. Findings from diversification methods coupled with colobine biogeographic history provide compelling evidence that decreasing availability of new adaptive zones during colonization of Asia together with constraints presented by dietary specialization underlie temporal changes in diversification in the Asian but not African clade. Additionally, departures from the EO model likely reflect iterative diversification events in Asia.

The meaning of weaning in wild Phayre's leaf monkeys: Last nipple contact, survival, and independence

In primates and other mammals, weaning is an equivocal concept, as is reflected in the numerous ways it is measured: a) first intake of solid food, b) conflict over access to the nipple, c) ability to survive without mother, d) maternal resumption of cycling, or e) the cessation of nipple contact. The lack of a consistent definition means that weaning age, although it falls between gestation (fetal growth) and age at first reproduction (most energy diverted from growth), is currently not a reliable life history variable capturing offspring independence. Using data for wild Phayre's leaf monkeys (Trachypithecus phayrei crepusculus) at Phu Khieo Wildlife Sanctuary, Thailand (51 offspring, four groups), we asked whether the end of nipple contact indicates offspring independence as measured by survival to 3 years. To establish a baseline for the onset of independence, we assessed the youngest age at which individuals were orphaned (15-17 months) but then survived to 3 years. Next we determined that offspring age at last nipple contact (19.0 months) was comparable to two other independently calculated measures: offspring age at mother's first postpartum ovulation (11.5 months), and age at mother's re-conception (15.6 months). Using these separate "starting points," we arrived at similar ages for nipple contact cessation (18.4 and 19.2 months, respectively). Overall, in wild (but not in provisioned) Asian colobines, age at last nipple contact was allometrically related to adult female body mass, supporting its designation as a life history variable. Future comparisons need to show if this holds for other taxa.

Genetic Polymorphism and Zoonotic Potential of Enterocytozoon bieneusi from Nonhuman Primates in China

Enterocytozoon bieneusi is an important zoonotic pathogen. To assess the human-infective potential of E. bieneusi in nonhuman primates (NHPs), we examined the prevalence and genotype distribution of E. bieneusi in 23 NHP species by PCR and sequence analysis of the ribosomal internal transcribed spacer (ITS). A total of 1,386 fecal specimens from NHPs from five provinces in China were examined, and E. bieneusi was detected in 158 (11.4%) specimens from five NHP species, including cynomolgus monkey (67.7%), rhesus macaque (8.8%), Japanese macaque (33.3%), white-headed langur (13.6%), and golden snub-nosed monkey (3.5%) (P < 0.0001). The infection rates were 70.2%, 21.5%, 8.5%, 7.5%, and 5.6% in Guangdong, Yunnan, Guangxi, Henan, and Sichuan Provinces, respectively (P < 0.0001). The prevalence was significantly higher in captive (13.7%) than in free-range (5.0%) animals (P < 0.0001). Altogether, 16 ITS genotypes were observed, including nine known genotypes (IV, D, Henan V, Peru8, PigEBITS7, EbpC, Peru11, BEB6, and I) and seven new genotypes (CM1 to CM7). The common genotypes included CM1, IV, and D, which were detected in 43, 31, and 30 specimens, respectively. Phylogenetic analysis revealed that seven known genotypes (but not BEB6 and I) and four new genotypes (CM1, CM2, CM3, and CM6) belonged to the previously described group 1 with zoonotic potential. Genotypes CM5 and CM7 clustered with group 2, whereas genotype CM4 did not belong to any of the previously proposed groups. It was concluded that humans and NHPs residing in the same geographical location shared the same E. bieneusi genotypes, indicating a potential role of these animals in the zoonotic transmission of E. bieneusi.

Individual, contextual, and age-related acoustic variation in Simakobu (Simias concolor) loud calls.

Primate loud calls have the potential to encode information about the identity, arousal, age, or physical condition of the caller, even at long distances. In this study, we conducted an analysis of the acoustic features of the loud calls produced by a species of Asian colobine monkey (simakobu, Simias concolor). Adult male simakobu produce loud calls spontaneously and in response to loud sounds and other loud calls, which are audible more than 500 m. Individual differences in calling rates and durations exist, but it is unknown what these differences signal and which other acoustic features vary among individuals. We aimed to describe the structure and usage of calls and to examine acoustic features that vary within and among individuals. We determined the context of 318 loud calls and analyzed 170 loud calls recorded from 10 adult males at an undisturbed site, Pungut, Siberut Island, Indonesia. Most calls (53%) followed the loud call of another male, 31% were spontaneous, and the remaining 16% followed a loud environmental disturbance. The fundamental frequency (F0) decreased while inter-unit intervals (IUI) increased over the course of loud call bouts, possibly indicating caller fatigue. Discriminant function analysis indicated that calls were not well discriminated by context, but spontaneous calls had higher peak frequencies, suggesting a higher level of arousal. Individual calls were distinct and individuals were mainly discriminated by IUI, call duration, and F0. Loud calls of older males had shorter IUI and lower F0, while middle-aged males had the highest peak frequencies. Overall, we found that calls were individually distinct and may provide information about the age, stamina, and arousal of the calling male, and could thus be a way for males and females to assess competitors and mates from long distances.

First detailed reconstruction of the karyotype of Trachypithecus cristatus (Mammalia: Cercopithecidae).

BackgroundThe chromosomal homologies of human (Homo sapiens = HSA) and silvered leaf monkey (Trachypithecus cristatus = TCR) have been previously studied by classical chromosome staining and by fluorescence in situ hybridization (FISH) applying chromosome-specific DNA probes of all human chromosomes in the 1980s and 1990s, respectively.ResultsHowever, as the resolution of these techniques is limited we used multicolor banding (MCB) at an ~250-band level, and other selected human DNA probes to establish a detailed chromosomal map of TCR. Therefore it was possible to precisely determine evolutionary conserved breakpoints, orientation of segments and distribution of specific regions in TCR compared to HSA. Overall, 69 evolutionary conserved breakpoints including chromosomal segments, which failed to be resolved in previous reports, were exactly identified and characterized.ConclusionsThis work also represents the first molecular cytogenetic one characterizing a multiple sex chromosome system with a male karyotype 44,XY1Y2. The obtained results are compared to other available data for old world monkeys and drawbacks in hominoid evolution are discussed.

Nutmeg-Vertebrate Interactions in the Asia-Pacific Region: Importance of Frugivores for Seed Dispersal in Myristicaceae

In tropical forests, large frugivores are assumed to be important seed dispersers for many large-seeded trees such as the Myristicaceae, a widespread and common family. However, not all frugivores are effective seed dispersers, and understanding which frugivores are effective is vital for conservation biology. Here, we summarize the available data on fruit characteristics and frugivores for a large number of Myristicaceae species in the Asia-Pacific region and suggest future directions for evaluating the effects of disperser loss for these trees. Studies of fruit characteristics of Myristicaceae were highly biased toward morphological information, and few studies examined reproductive phenology or fruit chemistry. We identified 338 instances of nutmeg-frugivore interactions that included 129 species of Myristicaceae and 109 species of frugivores, including 40 bird, 68 mammal, and one reptile species. Large birds were major seed dispersers for this tree family. These bird species, such as hornbills and pigeons, consumed a variety of nutmeg species, remained briefly at fruiting trees, and dispersed intact seeds far from the parent trees in the forest. Although most seeds dispersed by birds subsequently suffered high seed predation by rodents, some germinated and established as seedlings, indicating the qualitative effectiveness of large birds as seed dispersers for Myristicaceae. Mammals were also major consumers of Myristicaceae. Gibbons, macaques, and civets potentially acted as long-distance dispersers for some nutmeg species. Orangutans, leaf monkeys, squirrels, and rodents consumed a variety of nutmeg species, but their roles as seed dispersers for Myristicaceae remain unclear. Studies of nutmeg-vertebrate interactions have typically focused on frugivory, whereas few studies have specifically quantified the effectiveness of frugivores as seed dispersers; thus, it remains difficult to evaluate the effect of frugivore loss on the populations of most nutmeg species in this region. Further studies of nutmeg-frugivore interactions are of great ecological importance, and the results of such studies will contribute to a general understanding of which evolutionary forces may have shaped current nutmeg-frugivore interactions in tropical forests worldwide.

Home-Range Use and Activity Patterns of the Red Langur (Presbytis rubicunda) in Sabangau Tropical Peat-Swamp Forest, Central Kalimantan, Indonesian Borneo

Knowledge of a species’ ranging patterns is vital for understanding its behavioral ecology and vulnerability to extinction. Given the abundance and even distribution of leaves in forested habitats, folivorous primates generally spend less time feeding; more time resting; have shorter day ranges; and require smaller home ranges than frugivorous primates. To test the influence of frugivory on ranging behavior, we established the activity budget and home-range size and use in a highly frugivorous population of the Borneo-endemic colobine, Presbytis rubicunda, within Sabangau tropical peat-swamp forest, Central Kalimantan, and examined relationships between fruit availability and ranging patterns. We collected 6848 GPS locations and 10,702 instantaneous focal behavioral scans on a single group between January and December 2011. The group had the largest home-range size recorded in genus Presbytis (kernel density estimates: mean = 108.3 ± SD 3.8 ha, N = 4 bandwidths). The annual activity budget comprised 48 ± SD 4.0% resting; 29.3 ± SD 3.9% feeding, 14.2 ± SD 2.5% traveling, and 0.4 ± SD 0.4% social behaviors. Mean monthly day-range length was the highest recorded for any folivorous primate (1645 ± SD 220.5 m/d). No significant relationships existed between ranging variables and fruit availability, and ranging behaviors did not vary significantly across seasons, potentially owing to low fluctuations in fruit availability. Our results suggest that colobine monkeys maintain larger than average ranges when high-quality food resources are available. Their extensive range requirements imply that protecting large, contiguous tracts of habitat is crucial in future conservation planning for Presbytis rubicunda.

Feeding Ecology of Red Langurs in Sabangau Tropical Peat‐Swamp Forest, Indonesian Borneo: Extreme Granivory in a Non‐Masting Forest

Southeast Asia's lowland dipterocarp forests experience supra-annual "mast" fruiting and flowering events, in which the majority of trees reproduce simultaneously at irregular intervals, with extensive intervening periods of very low primate food availability. This scarcity of food results in a negative energy balance and a reliance on "fallback foods" in some primate species. By contrast, ombrogenous tropical peat-swamp forests are non-masting, and show lower variability of food availability. We sought to test the influence of fruit availability on primate diet and preference in peat-swamp habitats and assess whether it differs from masting forests. We collected behavioral-dependent feeding data on three adult females in a group of red langurs (Presbytis rubicunda: Colobinae) between January and December 2011 in Sabangau tropical peat-swamp forest, Central Kalimantan, Indonesia, as colobine monkeys are adaptated for folivory, and are therefore generally considered less reliant on temporally variable fruits than monogastric primates. We documented the highest level of granivory recorded to date in colobine monkeys: mean annual diet comprised 76.4% seeds and 7.3% other fruit parts; 7.7% young and 2.5% mature leaves; 2.8% flowers; 2.6% piths, and <1% on other minor food items. Fruit availability was fairly constant throughout the year and fruit parts were consumed at consistently higher levels than expected based on availability, confirming that fruit is preferred. Leaves and flowers were consumed consistently less than expected and thus are not preferred. There were no significant correlations between preferred food availability and consumption of potential fallback foods, suggesting that reliance on fallback foods did not occur in Sabangau during the study period. Furthermore, consumption of fruit was not significantly correlated with its availability. Our findings suggest that the relatively constant availability of fruit in this habitat affords P. rubicunda regular access to a nutritionally superior food, and that reliance on fallback foods is therefore not required.

Leaf selection by two Bornean colobine monkeys in relation to plant chemistry and abundance.

Focusing on the chemical basis of dietary selection while investigating the nutritional ecology of animals helps understand their feeding biology. It is also important to consider food abundance/biomass while studying the mechanism of animal food selection. We studied leaf selection in two Bornean folivorous primates in relation to plant chemistry and abundance: proboscis monkeys inhabiting a secondary riverine forest and red leaf monkeys inhabiting a primary forest. Both species tended to prefer leaves containing higher protein levels, although more abundant plant species were chosen within the preferred species, probably to maximise energy gain per unit time. However, the two species showed clear differences in their detailed feeding strategy. Red leaf monkeys strictly chose to consume young leaves to adapt to the poor nutritional environment of the primary forest, whereas proboscis monkeys were not highly selective because of the better quality of its common food in the riverine forest.

The Conservation Status of Phayre's Leaf MonkeyTrachypithecus phayreiin Lao PDR

Phayre's leaf monkey Trachypithecus phayrei had fewer confirmed 1990s records in Lao PDR than any other monkey known from the country, suggesting a general rarity there. This review collates records, historical and recent, to evaluate its national conservation status. Although in no area have surveyors regularly and readily seen the species, records come from a wide scatter of areas in and north/west of Nam Kading National Protected Area to the far north and west of the country. There are inconclusive indications of occurrence up to 120 km south of confirmed records, but this part of the country is well enough surveyed that the animal must be very rare there, if it occurs at all. Much of North Lao PDR comprises ragged highlands over 800 m altitude, but only one Phayre's leaf monkey field record is from above this height (at 1,125 m). Whether this apparent altitudinal restriction is a natural pattern or reflects heavy hunting is unclear. Despite their lower-lying locations, records are not associated with gentle terrain. Most records come from forest with a heavily broken canopy and much tall bamboo; none is from deep within extensive closed-canopy forest. This might simply reflect the paucity of such forest within the known Lao geographic and altitudinal range, but a genuine habitat association with broken canopy and tall bamboo is likely. The status of Phayre's leaf monkey in Lao PDR is less grim than was feared a decade ago, and it inhabits three national protected areas, which are benefitting from long-term external collaboration. Nonetheless, its status in Lao PDR cannot yet be considered secure. Lao populations are probably relatively insignificant to the global status of T. phayrei as here taxonomically constituted.

Population Density and Abundance of Ebony Leaf Monkeys (Trachypithecus auratus) in West Bali National Park, Indonesia

Most of the information available on the conservation status of the ebony leaf monkey (Trachypithecus auratus), a spe- cies categorized as Vulnerable on The IUCN Red List, comes from studies conducted in Java. However, these findings may not be representative of other islands of the Indonesian archipelago, such as Bali. In order to estimate the density and abundance of the ebony leaf monkey population in Prapat Agung Peninsula, located in the northern part of the West Bali National Park, Indonesia, we used repeated line transect distance sampling, a standard method for census surveys of wild animal populations, including primates. The estimated group density, individual density, group size, and total population size were 0.95 group/km², 7.11 indi- viduals/km², 7.49 individuals/group, and 422 individuals, respectively. The comparison of these values with those obtained from a previous study conducted 10 years ago in the same area and with the same method showed a marked decrease in population density and abundance as well as changes in the spatial distribution of ebony leaf monkeys. Our data suggest that such trends may be at least partially explained by anthropogenic disturbances, including illegal logging activities and habitat fragmentation. Given these alarming signs, and to better assess trends in the Balinese ebony leaf monkey populations change over time, we urge for the replication of the same survey design in the same study area, at least every five years. Such a survey effort is crucial not only to better understand the socio-ecology of ebony leaf monkeys, but also to determine conservation priorities and devise management plans related to the protection of the populations of this vulnerable primate species in Indonesia.