Birth-related behaviors in wild proboscis monkeys (Nasalis larvatus)

Two births of wild proboscis monkeys took place during a 1991/1992 field study at Tanjung Puting National Park, Indonesia. After conception, both females continued copulating with their group’s male. One of the births took place during the night, the other during mid-morning. In the latter case, the infant was born unassisted while the members of the group watched the birthing process. After parturition, the mother consumed the placenta.     

Feeding ecology of the proboscis monkey (Nasalis larvatus)

Proboscis monkey (Nasalis larvatus) feeding behavior and ecology were studied at the Natai Lengkuas Station, Tanjung Puting National Park, Kalimantan Tengah, Indonesia. Data on feeding behavior were collected using scan sampling during group follows. Three vegetational plots containing 1,732 trees were established and monitored monthly for changes in fruit, flower, and young leaf production. Basal area and canopy cover were calculated and used in estimating food abundance. Proboscis monkeys were found to be folivore/frugivores, specializing in seed consumption. At least 55 different plant species were used as food sources, with a marked preference for Eugenia sp. 3/4,Ganua motleyana and Lophopetalum javanicum. These tree species were among the most frequent and most dominant. However, proboscis monkeys were selective feeders; use of tree species as food sources was not based simply on relative density. During times of low food abundance and/or availability proboscis monkeys switched dietary strategies and increased dietary diversity. The average total home range was estimated to be 130.3 ha, with an average group density of 5.2 groups per km². The average biomass per km² was estimated to be 499.5 kg. Given their high biomass and predilection for consuming seeds of dominant species, proboscis monkeys may help to maintain and increase vegetational diversity.     

Habitat use,ranging behaviour,and food habits of the proboscis monkey,Nasalis larvatus (van Wurmb), in Sarawak

Studies on the ecology of the proboscis monkey were conducted in seven areas of Sarawak during 1980–1981. Groups were found in a variety of riparian and coastal habitats but where high forests occurred they appeared to be preferred over other adjacent types. Undisturbed tidal forests were widely used but were preferred only where high forest was lacking or limited in extent. Clear-felled tidal forests and areas around human settlements were completely avoided, although some use was made of selectively felled tidal forests, remnant tidal forests adjacent to agricultural land, and selectively logged high forest. Monkeys slept primarily and perhaps exclusively along river edges where these were available, moving inland up to 750m during the day and returning to the riverside in late afternoon. Groups often split up into distinct subunits during daily movements. Feeding occurred throughout the day and in all habitats occupied. Proboscis monkeys were observed feeding on at least 90 plant species, including leaves or shoots of 75 species, fruits of 15 species, seeds of 10 species, and flowers of 4 species. Certain tidal forest species (Sonneratia alba, Avicennia alba, Bruguiera gymnorrhiza, Rhizophora spp.) appeared to be the single most important food plants, although where high forests were available more feeding time was spent in these types than in tidal forests or other habitats.     

Social organization and ecology of proboscis monkeys (Nasalis larvatus) in mixed coastal forest in Sarawak

Data are presented from a 16-month study of proboscis monkeys in an area of mixed coastal forest in Sarawak. The population density, social organization, and feeding and ranging behavior are described in detail. Results are compared with those from other primates in an attempt to understand why females of certain species (including proboscis monkeys) transfer between social groups. The scarcity of available food and reasons for the limited habitat preferences of proboscis monkeys are also discussed.     

Selection of river crossing location and sleeping site by proboscis monkeys (Nasalis larvatus) in Sabah, Malaysia

From May 2005-2006, selections of river crossing locations and sleeping sites used by a one-male group (BE-Group) of proboscis monkeys (Nasalis larvatus) were investigated along the Menanggul River, tributary of the Kinabatangan River, Sabah, Malaysia. The frequency of river crossings for focal monkeys in the BE-Group was significantly higher at locations with narrow branch-to-bank distances. Branch-to-bank distances were defined as the distances between the longest tree branches extending over the river and the bank of river on each side. This was measured in areas crossed by the monkeys. The focal monkeys used locations with a higher probability of successful river crossings that did not require jumping into the water and swimming across than those that did. The frequency of sleeping site usage by the BE-Group was positively correlated with the frequency of using river crossing locations by the focal monkeys. Previous reports on predation of proboscis monkeys indicate that clouded leopards (Neofelis diardi) and crocodilians (Tomistoma schlegeli and Crocodylus porosus) may be the major terrestrial and aquatic predators of these monkeys. The selection of river crossing locations by proboscis monkeys may be influenced both by the threat of these predators and the location of suitable and protected sleeping sites. Finally, sleeping sites locations that offer arboreal escape routes may protect proboscis monkeys from leopard attack.     

Ecology and behavior of the wild proboscis monkey,Nasalis larvatus (Wurmb), in Sabah,Malaysia

Proboscis monkeys,Nasalis larvatus (Wurmb), were investigated in the Padas Bay and Kinabatangan River areas, Sabah, from July 1968 to March 1969. The proboscis monkey is a common, widely distributed species of coloboids in Sabah, living in the various vegetations that extend from the coastal swamp to the inland plain. It appears to have a terrestrial tendency, compared with other coloboids, moving around on the ground in the forest and extending its activity, sometimes, to the open land along the river beach. The number of monkey in a troop, we observed, ranged from 11 to 32, and almost all troops were composed of several adult males, many more adult females, and immature animals. The adult males appear to play the role of leaders in the troop through their characteristic behavior, attacking, threatening, warning, watching, etc., other troop members or invaders. Each troop always emitted various boisterous vocalizations which were divided into 14 types.     

Ranging Behavior of Proboscis Monkeys (Nasalis larvatus) in the Lower Kinabatangan, Northern Borneo

I studied the ranging behavior of proboscis monkeys (Nasalis larvatus) at two sites in the Lower Kinabatangan Region of northern Borneo. I collected data on ranging behavior via scan sampling during group follows. Groups of Nasalis larvatus had ranges overlapping those of other groups in each area. I observed no territorial behavior. Groups of Nasalis larvatus occasionally swam across the Kinabatangan River, and frequently across its tributaries. The home range size of a focal one-male group (SU1) was 220.5 ha. The group traveled farther on days when the proportion of young leaves in the diet was higher. In addition, SU1 used particular areas when they fed on flowers and fruits. Apparently, rainfall and phenology did not influence ranging patterns.     

Clouded leopard (<Emphasis Type="Italic">Neofelis diardi</Emphasis>) predation on proboscis monkeys (<Emphasis Type="Italic">Nasalis larvatus</Emphasis>) in Sabah,Malaysia

In this study, we have reported two direct observations of individuals from a one-male group of proboscis monkeys (Nasalis larvatus) being killed by clouded leopards (Neofelis diardi) in the riverine forest along the Menanggul river, a tributary of the Kinabatangan river in Sabah, Malaysia. One of the two individuals was an infant female and the other was a juvenile female. Based on literature reviews and the observations reported here, we suggest that clouded leopard and crocodile might be significant potential predators of proboscis monkeys of any age or sex and that predation threats elicit the monkeys' anti-predator strategies. Moreover, the observations of the monkeys' behaviour when the group is attacked by a predator suggest that the adult males in one-male groups play an important role as protectors.     

Does intraspecific variation in social systems explain reported differences in the social structure of the proboscis monkey (Nasalis larvatus)?

The social structure of proboscis monkeys (Nasalis larvatus) was investigated in the Brunei Bay area of Brunei Darussalam (Northern Borneo). Intraspecific variability in social systems had been suggested to occur in this species, with social structure varying with habitat differences. Prior reports for this area suggested that groups contained several males, females, and offspring and were unstable. Contrary to these reports, I found that the monkeys were organized into groups containing one male, several females, and offspring. These groups associated at sleeping sites at the river’s edge, thus forming a secondary level of organization. This is the same social system reported in Sarawak, Malaysia and Kalimantan, Indonesia in different habitat types. It appears that methodological differences may account for the discrepancies between reports. I have found no evidence to suggest that intraspecific variation in social systems occurs in this species.     

Intestinal parasites and bacteria of mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda

A survey in 1994 examined intestinal helminths and bacterial flora of mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda. Parasites and bacteria were identified to genus in the feces of two groups of tourist-habituated and one group of non-tourist-habituated mountain gorillas. Eggs were identified as those of an anoplocephalid cestode, and nematode eggs representative of the genera: Trichuris, Ascaris, Oesophagostomum, Strongyloides, and Trichostrongylus. This is the first report of Ascaris lumbricoides-like eggs in mountain gorillas. Fecal samples (n=76) from all groups contained helminth eggs, with strongyle eggs and anoplocephalid eggs being the most common. Salmonella and Campylobacter were found in both gorilla groups. Regular long-term non-invasive fecal monitoring of the populations of mountain gorillas is essential for the prevention and identification of potential health threats by intestinal parasites and bacteria in this highly endangered subspecies.This revised version was published online in April 2005 with corrections to the cover date of the issue.     

Demographics and parasites of African buffalo (Syncerus caffer Sparrman, 1779) in Ruaha National Park,Tanzania

The number of African buffaloes (Syncerus caffer Sparrman, 1779) inhabiting Ruaha National Park, Tanzania, is thought to be declining, but little data exist to determine whether the population is actually in decline. As an initial phase of collecting population data, we conducted demographic surveys, faecal egg counts and gastrointestinal parasite identification in Ruaha's buffalo herds in September 2011 and 2013. Most herds encountered in the two surveys appeared to be in good health, but with fewer calves in 2013 compared with 2011. The herd‐level body condition score was positively associated with the number of calves per 100 cows after adjusting for year, and the lower number of offspring in 2013 could possibly be associated with a below average rainfall in the 2012–2013 rainy season. Mean herd‐level egg counts ranged from 83 to 140 and from 28 to 113 eggs per g faeces in 2011 and 2013, respectively. Haemonchus, Nematodirus, Cooperia and Oesophagostomum spp., as well as coccidian oocysts, were detected in the population. Monitoring herd demographics and baseline health parameters over time will provide insight into population performance, increase the understanding of population stressors and contribute to buffalo conservation within Ruaha National Park and other protected areas of Africa.     

Density estimates of Panamanian owl monkeys (Aotus zonalis) in three habitat types

The resolution of the ambiguity surrounding the taxonomy of Aotus means data on newly classified species are urgently needed for conservation efforts. We conducted a study on the Panamanian owl monkey (Aotus zonalis) between May and July 2008 at three localities in Chagres National Park, located east of the Panama Canal, using the line transect method to quantify abundance and distribution. Vegetation surveys were also conducted to provide a baseline quantification of the three habitat types. We observed 33 individuals within 16 groups in two out of the three sites. Population density was highest in Campo Chagres with 19.7 individuals/km² and intermediate densities of 14.3 individuals/km² were observed at Cerro Azul. In la Llana A. zonalis was not found to be present. The presence of A. zonalis in Chagres National Park, albeit at seemingly low abundance, is encouraging. A longer‐term study will be necessary to validate the further abundance estimates gained in this pilot study in order to make conservation policy decisions. Am. J. Primatol. 72:187–192, 2010. © 2009 Wiley‐Liss, Inc.     

From research to implementation: Nature conservation in the Eastern Rhodopes mountains (Greece and Bulgaria), European Green Belt

Nature conservation should ideally build on the scientific recommendations that are concluded from applied conservation research, as well as on monitoring schemes that evaluate the effectiveness of recommendations. We considered as a case study a system of six protected areas located in the Eastern Rhodopes mountains in the southern part of the European Green Belt (EGB). To investigate nature conservation effectiveness, we reviewed 196 articles from scientific journals and books, eight doctoral and master theses, and 39 scientific reports regarding the Greek (one protected area, 428 km²) and the Bulgarian (five protected areas, 904 km²) part of the study area. We extracted 743 conservation recommendations, and through questionnaires completed by 10 local experts, we found that 74% of the recommendations were familiar for the experts. In the Greek (GR) and the Bulgarian part (BG) only 52% and 16%, respectively, of the recommendations were implemented, and only 15% (GR) and 3.1% (BG) were implemented and evaluated regarding their effectiveness. According to the experts, the main reasons for non-implementation and non-evaluation were absence or incompetence of the responsible authorities. Some recommendations obtained a remarkable low rate of implementation, such as those regarding agriculture and livestock rearing practices (GR: 29%, BG: 16%) or mammal conservation (GR: 0%, BG: 16%). Some other recommendations obtained rather high rates at least for Greece, such as tourism and environmental education (GR: 57%, BG: 42%) and bird conservation (GR: 57%, BG: 11%). We found that researchers and conservation managers at both sides of the Greek-Bulgarian border face similar implementation problems, related often to the lack of political will for nature conservation and establishment of competent authorities. The role of the EGB is crucial in enhancing the established cross-border collaborations between stakeholders involved in nature conservation.     

Without management interventions,endemic wet‐sclerophyll forest is transitioning to rainforest in World Heritage listed K’gari (Fraser Island), Australia

Wet‐sclerophyll forests are unique ecosystems that can transition to dry‐sclerophyll forests or to rainforests. Understanding of the dynamics of these forests for conservation is limited. We evaluated the long‐term succession of wet‐sclerophyll forest on World Heritage listed K'gari (Fraser Island)—the world's largest sand island. We recorded the presence and growth of tree species in three 0.4 hectare plots that had been subjected to selective logging, fire, and cyclone disturbance over 65 years, from 1952 to 2017. Irrespective of disturbance regimes, which varied between plots, rainforest trees recruited at much faster rates than the dominant wet‐sclerophyll forest trees, narrowly endemic species Syncarpia hillii and more common Lophostemon confertus. Syncarpia hillii did not recruit at the plot with the least disturbance and recruited only in low numbers at plots with more prominent disturbance regimes in the ≥10 cm at breast height size. Lophostemon confertus recruited at all plots but in much lower numbers than rainforest trees. Only five L. confertus were detected in the smallest size class (<10 cm diameter) in the 2017 survey. Overall, we find evidence that more pronounced disturbance regimes than those that have occurred over the past 65 years may be required to conserve this wet‐sclerophyll forest, as without intervention, transition to rainforest is a likely trajectory. Fire and other management tools should therefore be explored, in collaboration with Indigenous landowners, to ensure conservation of this wet‐sclerophyll forest.