Endemic to Borneo, the proboscis monkey or Long-Nosed Monkey (Nasalis larvatus), also known as
monyet belanda or bekantan, is an endangered primate that inhabits coastal mangrove, riverine and lowland forests. This species is easily identified by its prominent nose, which is particularly pendulous in adult males.Proboscis monkeys live in troops and are primarily diurnal and arboreal. Their specialized digestive system allows them to feed primarily on leaves and other plant material, and give them a pot-bellied appearance. They are also known to be good swimmers and may dive into water to escape danger. Wild proboscis monkeypopulations are threatened by habitat loss and conversion, hunting, and other human activities. A small captive population of this species is maintained by zoos in Indonesia and Singapore.The Southeast Asia Zoo Association (SEAZA) and the Indonesian Zoological Parks Association(Perhimpunan Kebun Binatang Seluruh Indonesia, or PKBSI) have identified the proboscis monkey as a high priority species for ex situ and in situ conservation. As part of their conservation initiative, it was recommended to conduct a Population and Habitat Viability Assessment (PHVA) workshop for the proboscis monkey in Indonesia to assist in the development of conservation strategies for the species. Two international conservation workshops were held in early December in Cisarua-Bogor, West Java, Indonesia under the coordination of CBSG Indonesia and its parent office of CBSG (Conservation Breeding Specialist Group of the IUCN-The World Conservation Union). A two-day training workshop in CBSG skills and processes was held at Safari Garden Hotel on 2-3 December, followed by an Indonesian Proboscis Monkey Population and Habitat Viability Assessment (PHVA) workshop on 4-6 December. Both workshops were attended by participants from several Asian countries and demonstrated strong international cooperation among a variety of organizations, both in situ and ex situ. These workshops were made possible through the concerted 
efforts of several CBSG offices: workshop organization was handled by CBSG Indonesia (Jansen
Manansang, Convener), financial support was provided by CBSG Japan (Hiroshi Hori, Convener), and CBSG Europe and the CBSG main office provided trainers and workshop facilitators.Support and cooperation also were provided by the Southeast Asian Zoo Association (SEAZA), the Indonesian Zoological Parks Association (PKBSI), the Indonesian Forestry Department (PHKA), the Research Center for Biology (LIPI), and Taman Safari Indonesia (TSI). Participants ranged from nine countries and included representatives from Asian zoos, forestry, universities and conservation NGOs. Inbreeding Depression: We included inbreeding depression in these models. We used the median value for mammals in captivity of 3.14 lethal equivalents (Ralls et al., 1988). We modeled inbreeding depression forjuvenile survival only. We assumed that 50% of the lethal equivalents were due to completely recessive lethal alleles and the other 50% was due to recessive alleles of smaller effect.Environmental Concordance of Reproduction and Survival: The working group felt that the major causes of environmental variation (disease, drought, forest fires) were likely to impact both adults and juveniles in a way that would produce a strong correlation between the two demographic parameters.Correlation among Populations in Environmental Variation: Because the populations modeled are scattered throughout Kalimantan and are thought to be genetically isolated from each other, the working group felt that the overall correlation among the individual populations was fairly low. However, widespread drought and the increased risk of forest fires is something that can impact all of Borneo in a correlated fashion. We set the correlation at 0.30. Catastrophes: The working group felt that the single greatest non-anthropogenic threat to the proboscis monkey was the threat of forest fire. However, even this natural threat is increased in frequency and intensity due to its synergism with human-
Manansang, Convener), financial support was provided by CBSG Japan (Hiroshi Hori, Convener), and CBSG Europe and the CBSG main office provided trainers and workshop facilitators.Support and cooperation also were provided by the Southeast Asian Zoo Association (SEAZA), the Indonesian Zoological Parks Association (PKBSI), the Indonesian Forestry Department (PHKA), the Research Center for Biology (LIPI), and Taman Safari Indonesia (TSI). Participants ranged from nine countries and included representatives from Asian zoos, forestry, universities and conservation NGOs. Inbreeding Depression: We included inbreeding depression in these models. We used the median value for mammals in captivity of 3.14 lethal equivalents (Ralls et al., 1988). We modeled inbreeding depression forjuvenile survival only. We assumed that 50% of the lethal equivalents were due to completely recessive lethal alleles and the other 50% was due to recessive alleles of smaller effect.Environmental Concordance of Reproduction and Survival: The working group felt that the major causes of environmental variation (disease, drought, forest fires) were likely to impact both adults and juveniles in a way that would produce a strong correlation between the two demographic parameters.Correlation among Populations in Environmental Variation: Because the populations modeled are scattered throughout Kalimantan and are thought to be genetically isolated from each other, the working group felt that the overall correlation among the individual populations was fairly low. However, widespread drought and the increased risk of forest fires is something that can impact all of Borneo in a correlated fashion. We set the correlation at 0.30. Catastrophes: The working group felt that the single greatest non-anthropogenic threat to the proboscis monkey was the threat of forest fire. However, even this natural threat is increased in frequency and intensity due to its synergism with human-
caused deforestation and global climate change. We modeled this as Breeding System: The species is
polygynous (long-term polygyny). Successful males were assumed to breed with an average of 1.6 females. the single catastrophe facing these populations. It should be recognized, however, that what is being modeled as a single catastrophe (forest fires) often combines many interacting environmental perturbations. Forest firesare more likely during drought conditions that have already stressed the populations. Mortality from the forest fires may actually stem from starvation brought on by the loss of food resources after the fire. Malnutrition and crowding, due to habitat loss from forest fires, may trigger disease epidemics. Thus, the catastrophe regime may include a host of environmental factors directly or indirectly related to forest fires. Age of First Reproduction: Expert opinion was five years of age for females and six years of age for males.Maximum Age of Reproduction: Considerable variation existed among the experts’ guess as to the maximum age of reproduction for female proboscis monkeys. We chose 22 years, because it was the median value suggested to the working group and agreed well with data from captive populations.Proportion of Females Breeding: We used a combination of unpublished data (from Malaysia), expert opinion, and the life histories of other monkeys of similar size or similar ecology to arrive at an estimate of 46.1% with a standard deviation of 7.0%.Offspring Number: Twinning in proboscis moneys is so rare that we assumed that all births consisted of a single individual.Source: Animal Discovery-chanel
polygynous (long-term polygyny). Successful males were assumed to breed with an average of 1.6 females. the single catastrophe facing these populations. It should be recognized, however, that what is being modeled as a single catastrophe (forest fires) often combines many interacting environmental perturbations. Forest firesare more likely during drought conditions that have already stressed the populations. Mortality from the forest fires may actually stem from starvation brought on by the loss of food resources after the fire. Malnutrition and crowding, due to habitat loss from forest fires, may trigger disease epidemics. Thus, the catastrophe regime may include a host of environmental factors directly or indirectly related to forest fires. Age of First Reproduction: Expert opinion was five years of age for females and six years of age for males.Maximum Age of Reproduction: Considerable variation existed among the experts’ guess as to the maximum age of reproduction for female proboscis monkeys. We chose 22 years, because it was the median value suggested to the working group and agreed well with data from captive populations.Proportion of Females Breeding: We used a combination of unpublished data (from Malaysia), expert opinion, and the life histories of other monkeys of similar size or similar ecology to arrive at an estimate of 46.1% with a standard deviation of 7.0%.Offspring Number: Twinning in proboscis moneys is so rare that we assumed that all births consisted of a single individual.Source: Animal Discovery-chanel
