Impacts of fire and prospects for recovery in a tropical peat forest ecosystem.

Uncontrolled fires place considerable burdens on forest ecosystems, compromising our ability to meet conservation and restoration goals. A poor understanding of the impacts of fire on ecosystems and their biodiversity exacerbates this challenge, particularly in tropical regions where few studies have applied consistent analytical techniques to examine a broad range of ecological impacts over multiyear time frames. We compiled 16 y of data on ecosystem properties (17 variables) and biodiversity (21 variables) from a tropical peatland in Indonesia to assess fire impacts and infer the potential for recovery. Burned forest experienced altered structural and microclimatic conditions, resulting in a proliferation of nonforest vegetation and erosion of forest ecosystem properties and biodiversity. Compared to unburned forest, habitat structure, tree density, and canopy cover deteriorated by 58 to 98%, while declines in species diversity and abundance were most pronounced for trees, damselflies, and butterflies, particularly for forest specialist species. Tracking ecosystem property and biodiversity datasets over time revealed most to be sensitive to recurrent high-intensity fires within the wider landscape. These megafires immediately compromised water quality and tree reproductive phenology, crashing commercially valuable fish populations within 3 mo and driving a gradual decline in threatened vertebrates over 9 mo. Burned forest remained structurally compromised long after a burn event, but vegetation showed some signs of recovery over a 12-y period. Our findings demonstrate that, if left uncontrolled, fire may be a pervasive threat to the ecological functioning of tropical forests, underscoring the importance of fire prevention and long-term restoration efforts, as exemplified in Indonesia.

The power of gibbon songs: Going beyond the research to inform conservation actions.

Gibbons (Hylobatidae) are the smallest of the apes, known for their arboreal behavior and stereotyped songs. These species and sex-specific songs are often the subject of detailed studies regarding their evolution, responses to changing environments, involvement in social behavior, and used to design vocalization-based survey techniques to monitor population densities and trends. What is poorly understood is the value and impact of using the science and sound of gibbon vocalization and gibbon stories in education and outreach to complement nongovernmental organizations (NGOs) efforts. We present an example of how Borneo Nature Foundation, a NGOs based in Indonesia, is working to use the recordings of the songs of Bornean white-bearded gibbons (Hylobates albibarbis) to inform conservation actions and education efforts. Gibbons in Indonesia are often poorly known or understood by the public compared to orangutans (Pongo spp). We showcase how a field of study, namely primate acoustics, is an untapped resource to create digital content to engage with local, national and international communities and can be developed into educational tools in the form of storytelling, mobile apps and games, to highlight the plight of these threatened species and how to conserve them.

Mental health and well-being in primatology: Breaking the taboos.

We hope to raise awareness of mental health and well-being among primatologists. With this aim in mind, we organized a workshop on mental health as part of the main program of the Winter meeting of the Primate Society of Great Britain in December 2021. The workshop was very well received. Here, we review the main issues raised in the workshop, and supplement them with our own observations, reflections, and reading. The information we gathered during the workshop reveals clear hazards to mental health and suggests that we must collectively acknowledge and better manage both the hazards themselves and our ability to cope with them if we are to avert disaster. We call on institutions and learned societies to lead in seeking solutions for the benefit of primatologists and primatology.

Passive acoustic monitoring using smartphones reveals an alarming gibbon decline in a protected area in the central Annamite Mountains, Vietnam.

Monitoring populations is critical for understanding how they respond to anthropogenic disturbance and for management of protected areas. The use of passive acoustic monitoring can improve monitoring efforts as it allows for collection of data on vocal animals at spatial and temporal scales that are difficult using only human observers. In this study, we used a multiseason occupancy model to monitor occurrence, apparent extinction, and colonization probabilities of a northern yellow-cheeked gibbon, Nomascus annamensis population with acoustic data collected from mobile smartphones in Dakrong Nature Reserve, Vietnam. Forty-five sites were randomly selected for repeated surveys in 2019 and 2022. At each site, a mobile smartphone was attached to a tree and recorded sounds for 4.2 days and 3.89 days on average, in 2019 and 2022, respectively. We manually annotated spectrograms for the presence of gibbon calls, and we detected gibbons at 24 and 12 recording posts in 2019 and 2022, respectively. Estimated local apparent extinction from occupancy models was high with 67% of occupied sites in 2019 becoming unoccupied in 2022. Apparent colonization was low with ~25% of unoccupied sites in 2019 becoming occupied in 2022. As a result, the apparent occurrence probability declined from 0.58 in 2019 to 0.30 in 2022. If the absence of calls indicates that cells are unoccupied this would mean an alarming decline of the gibbon population in the nature reserve. We suggest that in the areas with high hunting pressure, monitoring intervals should be shortened to at least yearly. In addition, urgent actions, such as patrolling, or gun confiscation, should be implemented to conserve the gibbon populations in Dakrong Nature Reserve and other protected areas with the same management context.

Corrigendum: A Severe Lack of Evidence Limits Effective Conservation of the World's Primates.

[This corrects the article DOI: 10.1093/biosci/biaa082.].

Open-access platform to synthesize knowledge of ape conservation across sites.

Despite the large body of literature on ape conservation, much of the data needed for evidence-based conservation decision-making is still not readily accessible and standardized, rendering cross-site comparison difficult. To support knowledge synthesis and to complement the IUCN SSC Ape Populations, Environments and Surveys database, we created the A.P.E.S. Wiki (https://apeswiki.eva.mpg.de), an open-access platform providing site-level information on ape conservation status and context. The aim of this Wiki is to provide information and data about geographical ape locations, to curate information on individuals and organizations active in ape research and conservation, and to act as a tool to support collaboration between conservation practitioners, scientists, and other stakeholders. To illustrate the process and benefits of knowledge synthesis, we used the momentum of the update of the conservation action plan for western chimpanzees (Pan troglodytes verus) and began with this critically endangered taxon. First, we gathered information on 59 sites in West Africa from scientific publications, reports, and online sources. Information was compiled in a standardized format and can thus be summarized using a web scraping approach. We then asked experts working at those sites to review and complement the information (20 sites have been reviewed to date). We demonstrate the utility of the information available through the Wiki, for example, for studying species distribution. Importantly, as an open-access platform and based on the well-known wiki layout, the A.P.E.S. Wiki can contribute to direct and interactive information sharing and promote the efforts invested by the ape research and conservation community. The Section on Great Apes and the Section on Small Apes of the IUCN SSC Primate Specialist Group will guide and support the expansion of the platform to all small and great ape taxa. Similar collaborative efforts can contribute to extending knowledge synthesis to all nonhuman primate species.

Primate Selfies and Anthropozoonotic Diseases: Lack of Rule Compliance and Poor Risk Perception Threatens Orangutans.

Our understanding of the transmission of anthropozoonotic diseases between humans and non-human primates, particularly great apes due to their close genetic relationship with humans, highlights a serious potential threat to the survival of these species. This is particularly the case at tourism sites where risk of disease transmission is increased. We focus on the interaction between tourists and the Critically Endangered Sumatran orangutan (Pongo abelii) at Bukit Lawang in the Gunung Leuser National Park, Indonesia, before and after the park was closed due to the threat of COVID-19 in April 2020. Through analysis of posts on Instagram we determine the extent of compliance by visitors with the rule to keep a minimum distance of 10 m from orangutans and assess the positional behaviours of the orangutans. Of the 2,229 photographs we assessed between November 2019 and July 2020, 279 depicted one or more orangutans. Forty-two of these contained both a human and an orangutan, and of these all showed inappropriate behaviours (direct contact, feeding orangutans, close proximity <5 m) providing direct evidence of non-compliance with the 10-m distance rule. Most of these photographs additionally showed orangutans performing abnormal positional behaviours such as being low to or on the ground rather than their natural high position in the canopy; being near the ground and in close proximity to humans increases the risk of anthropozoonotic disease transmission. As expected, we found a significant decrease in number of photographs that were posted following the closure, and a decrease in the proportion of photographs that showed orangutans, or tourists feeding orangutans. Tourists do not seem to perceive that they pose risks to the orangutans and therefore increased awareness, education and enforcement of rules by all stakeholders, tourism bodies and government officials need to be actioned in order to safeguard this important population, which is crucial to the future survival of the Sumatran orangutan.

A Severe Lack of Evidence Limits Effective Conservation of the World's Primates.

Threats to biodiversity are well documented. However, to effectively conserve species and their habitats, we need to know which conservation interventions do (or do not) work. Evidence-based conservation evaluates interventions within a scientific framework. The Conservation Evidence project has summarized thousands of studies testing conservation interventions and compiled these as synopses for various habitats and taxa. In the present article, we analyzed the interventions assessed in the primate synopsis and compared these with other taxa. We found that despite intensive efforts to study primates and the extensive threats they face, less than 1% of primate studies evaluated conservation effectiveness. The studies often lacked quantitative data, failed to undertake postimplementation monitoring of populations or individuals, or implemented several interventions at once. Furthermore, the studies were biased toward specific taxa, geographic regions, and interventions. We describe barriers for testing primate conservation interventions and propose actions to improve the conservation evidence base to protect this endangered and globally important taxon.

Environment and time as constraints on the biogeographical distribution of gibbons.

We develop a time budget model for the hylobatid family with the aim of assessing the extent to which their contemporary and historical biogeographic distributions might be explained by ecological constraints. The model uses local climate to predict time budgets, and from this the limiting size of social group that animals could manage at a given location. The model predicts maximum group sizes that vary between 3 and 15 within the taxon's current distribution, indicating that the combination of their dietary and locomotor styles with the kinds of habitats they inhabit radically constrain group size. Beyond the edges of their current distribution, sustainable group size rapidly tends to zero, although if they had been able to bypass some of these areas, they would have found very suitable habitats in southern India and beyond the Wallace Line. While travel time would be a major constraint on group size at larger group sizes, as it is in great apes, the main factor limiting the gibbon's current distribution is the time they need to spend resting that is imposed on them by the environment. The model also indicates that gibbons would not now be able to survive in regions of central and southeastern China where they are known to have occurred within historical times, perhaps because historical climate change following the Little Ice Age of the C18th made these regions uninhabitable for them. Finally, our results indicate that gibbons have the ecological capacity to live in larger groups than they do, making it unlikely that their adoption of monogamy reflects purely ecological constraints.

A Short Cut to Mushrooms - Red Langur (Presbytis rubicunda) Consumption of Terrestrial Fungus.

We report the first in-depth evidence of targeted mushroom foraging in an Asian colobine. Using direct observations (2010-2018) and camera traps (2008-2018) in the Sebangau Forest, Central Kalimantan, Indonesian Borneo, we show how adult female red langurs (Presbytis rubicunda) are regularly descending to the ground to consume mushrooms. We recorded 82 counts (0.36% of all focal observations, n = 25,502) of the focal adult langur on the ground from direct observations of habituated groups, and 80 independent images/videos of red langurs on the ground were obtained from the camera traps representing 1.12% of total images (n = 7,145). Mushroom consumption took place in 4 families, representing 0.04% of total focal behaviour observations and 24.3% of total time feeding on the ground. From the camera trap photos, red langurs are spending 20% of time on the ground feeding. We speculate that mushrooms could be a supplementary food for adult female langurs as there is an increase in consumption in April and November.

Sleep patterns, daytime predation, and the evolution of diurnal sleep site selection in lorisiforms.

OBJECTIVES: Synthesize information on sleep patterns, sleep site use, and daytime predation at sleep sites in lorisiforms of Asia and Africa (10 genera, 36 species), and infer patterns of evolution of sleep site selection. MATERIALS AND METHODS: We conducted fieldwork in 12 African and six Asian countries, collecting data on sleep sites, timing of sleep and predation during daytime. We obtained additional information from literature and through correspondence. Using a phylogenetic approach, we established ancestral states of sleep site selection in lorisiforms and traced their evolution. RESULTS: The ancestral lorisiform was a fur-clinger and used dense tangles and branches/forks as sleep sites. Use of tree holes and nests as sleep sites emerged ∼22 Mya (range 17-26 Mya) in Africa, and use of bamboo emerged ∼11 (7-14) Mya in Asia and later in Africa. Fur clinging and some sleep sites (e.g., tree holes, nests, but not bamboo or dense tangles) show strong phylogenetic signal. Nests are used by Galagoides, Paragalago, Galago and Otolemur; tree holes by Galago, Paragalago, Sciurocheirus and Perodicticus; tangles by Nycticebus, Loris, Galagoides, Galago, Euoticus, Otolemur, Perodicticus and Arctocebus; all but Sciurocheirus and Otolemur additionally sleep on branches/forks. Daytime predation may affect sleep site selection and sleep patterns in some species of Nycticebus, Galago, Galagoides, Otolemur and Perodicticus. Most lorisiforms enter their sleep sites around sunrise and leave around sunset; several are active during twilight or, briefly, during daytime. CONCLUSION: Variations in sleep behavior, sleep patterns and vulnerability to daytime predation provide a window into the variation that was present in sleep in early primates. Overall, lorisiforms use the daytime for sleeping and no species can be classified as cathemeral or polycyclic.

Modelling Population Viability of Three Independent Javan Gibbon (Hylobates moloch) Populations on Java, Indonesia.

Population viability analysis is a predictive procedure that uses a combination of different modelling approaches to estimate species vulnerability to extinction. Javan gibbons (Hylobates moloch) are vulnerable to local extinction primarily due to loss of habitat and hunting for the illegal pet trade. Using the modelling software VORTEX, we assessed the status of Javan gibbons in 3 areas (Ujung Kulon National Park, Halimun-Salak National Park, and Dieng Mountains) which hold over half of the remaining estimated number of gibbons on Java. Ujung Kulon and Halimun-Salak are long-time protected areas, whereas Dieng Mountains remain unprotected. For each area, we calculated the probability of extinction over a 100-year time period by testing different area-specific scenarios (e.g., hunting, deforestation, and increase in carrying capacity). Our modelling suggests each of the populations has a high chance of becoming extinct within the next 100 years if hunting and deforestation persist. If these threats are eliminated, the model shows each of the populations are large enough to persist in the long term whilst maintaining high levels of current genetic diversity. We conclude that specific actions should be implemented to develop more inclusive conservation management practices, especially improving awareness regarding the illegal wildlife trade and increased protection of wild populations and their habitats.

Primate dietary ecology in the context of food mechanical properties.

Substantial variation exists in the mechanical properties of foods consumed by primate species. This variation is known to influence food selection and ingestion among non-human primates, yet no large-scale comparative study has examined the relationships between food mechanical properties and feeding strategies. Here, we present comparative data on the Young's modulus and fracture toughness of natural foods in the diets of 31 primate species. We use these data to examine the relationships between food mechanical properties and dietary quality, body mass, and feeding time. We also examine the relationship between food mechanical properties and categorical concepts of diet that are often used to infer food mechanical properties. We found that traditional dietary categories, such as folivory and frugivory, did not faithfully track food mechanical properties. Additionally, our estimate of dietary quality was not significantly correlated with either toughness or Young's modulus. We found a complex relationship among food mechanical properties, body mass, and feeding time, with a potential interaction between median toughness and body mass. The relationship between mean toughness and feeding time is straightforward: feeding time increases as toughness increases. However, when considering median toughness, the relationship with feeding time may depend upon body mass, such that smaller primates increase their feeding time in response to an increase in median dietary toughness, whereas larger primates may feed for shorter periods of time as toughness increases. Our results emphasize the need for additional studies quantifying the mechanical and chemical properties of primate diets so that they may be meaningfully compared to research on feeding behavior and jaw morphology.

Population of the Javan Gibbon (Hylobatesmoloch) in the Dieng Mountains, Indonesia: An updated estimation from a new approach.

The Javan gibbon (Hylobatesmoloch) is endemic to the island of Java and its distribution is restricted from the western tip of Java to the Dieng Mountains in Central Java. Unlike the other known habitats that hold a large population of Javan gibbons, the Dieng Mountains have not been protected and experience various threats. This study, which was conducted in 2018 and 2021, aimed to provide an update of the current density and population size of Javan gibbons in Dieng after the most recent study in 2010 and to investigate their relationships with habitat characteristics (vegetation and elevation). The triangulation method and a new acoustic spatial capture-recapture method were used to estimate group density. A new approach for extrapolation, based on the habitat suitability model, was also developed to calculate population size. The results show that the Javan gibbon population in the Dieng Mountains has most likely increased. The mean group density in each habitat type was high: 2.15 groups/km2 in the low suitable habitat and 5.55 groups/km2 in the high suitable habitat. The mean group size (3.95 groups/km2, n = 20) was higher than those reported in previous studies. The overall population size was estimated to be 1092 gibbons. This population increase might indicate the success of conservation efforts during the last decade. However, more effort should be made to ensure the long-term future of this threatened species. Although the density significantly differed between habitat suitability types, it was not influenced by the vegetation structure or elevation. A combination of multiple variables will probably have a greater effect on density variation.

Implications of large-scale infrastructure development for biodiversity in Indonesian Borneo.

Indonesia is embarking on an ambitious relocation of its capital city to Kalimantan, Borneo, bringing with it major urban and road infrastructure. Yet, despite being one of the world's most biologically diverse regions, the potential implications of this development for wildlife have yet to be fully assessed. We explored the potential impacts of the capital relocation, and road expansion and upgrades to critical habitat for medium-large mammals (>1 kg) using camera trap data from 11 forested landscapes. We applied Bayesian multi-species occupancy models to predict community and species-level responses to anthropogenic and environmental factors. We extrapolated spatial patterns of occupancy and species diversity across the forests of Kalimantan and identified "critical habitats" as the top 20th percentile of occupancy and species richness values. We subsequently overlapped these critical habitat layers with infrastructure impact zones to estimate the area that could potentially be affected by direct or secondary impacts. At both the community and species-level, distance to primary roads had the strongest negative influence on habitat-use. Occupancy was also influenced by forest quality and multidimensional poverty conditions in adjacent villages, demonstrating the sensitivity of biodiversity to socio-ecological pressures. Less than 1 % of the critical habitat for the threatened mammal community lay within the direct impact zone (30 km radius) of the capital relocation. However, approximately 16 % was located within 200 km and could potentially be affected by uncontrolled secondary impacts such as urban sprawl and associated regional development. The often-overlooked secondary implications of upgrading existing roads could also intersect a large amount of critical habitat for lowland species. Mitigating far-reaching secondary impacts of infrastructure development should be fully incorporated into environmental impact assessments. This will provide Indonesia with an opportunity to set an example of sustainable infrastructure development in the tropics.

Road Infrastructure and Primate Conservation: Introducing the Global Primate Roadkill Database.

As road infrastructure networks rapidly expand globally, especially in the tropics, previously continuous habitats are being fragmented, resulting in more frequent wildlife-vehicle collisions (WVC). Primates are widespread throughout many sub-/tropical countries, and as their habitats are fragmented, they are increasingly at risk of WVC. We created the Global Primate Roadkill Database (GPRD), the largest available standardized database of primate roadkill incidents. We obtained data from published papers, un-published and citizen science databases, anecdotal reports, news reports, and social media posts. Here, we describe the collection methods for the GPRD and present the most up-to-date version of the database in full. For each primate roadkill incident, we recorded the species killed, the exact location, and the year and month the roadkill was observed. At the time of publication, the GPRD includes 2862 individual primate roadkill records from 41 countries. As primates range in more than twice as many countries, the absence of data from these countries is not necessarily indicative of a lack of primate vehicular collisions. Given the value of these data for addressing both local and global research questions, we encourage conservationists and citizen scientists to contribute to the GPRD so that, together, we can better understand the impact road infrastructure has on primates and evaluate measures which may help mitigate risk-prone areas or species.

Sleeping site selection by agile gibbons: the influence of tree stability, fruit availability and predation risk.

Primates spend a significant proportion of their lives at sleeping sites: the selection of a secure and stable sleeping tree can be crucial for individual survival and fitness. We measured key characteristics of all tree species in which agile gibbons slept, including exposure of the tree crown, root system, height, species and presence of food. Gibbons most frequently slept in Dipterocarpaceae and Fabaceae trees and preferentially chose trees taller than average, slept above the mean canopy height and showed a preference for liana-free trees. These choices could reflect avoidance of competition with other frugivores, but we argue these choices reflect gibbons prioritizing avoidance of predation. The results highlight that gibbons are actively selecting and rejecting sleeping trees based on several characteristics. The importance of the presence of large trees for food is noted and provides insight into gibbon antipredatory behaviour.

Genetic characterization of nodular worm infections in Asian Apes.

Parasitic nematodes of Oesophagostomum spp., commonly known, as 'nodular worms' are emerging as the most widely distributed and prevalent zoonotic nematodes. Oesophagostomum infections are well documented in African non-human primates; however, the taxonomy, distribution and transmission of Oesophagostomum in Asian non-human primates are not adequately studied. To better understand which Oesophagostomum species infect Asian non-human primates and determine their phylogeny we analysed 55 faecal samples from 50 orangutan and 5 gibbon individuals from Borneo and Sumatra. Both microscopy and molecular results revealed that semi-wild animals had higher Oesophagostomum infection prevalence than free ranging animals. Based on sequence genotyping analysis targeting the Internal transcribed spacer 2 of rDNA, we report for the first time the presence of O. aculeatum in Sumatran apes. Population genetic analysis shows that there is significant genetic differentiation between Bornean and Sumatran O. aculeatum populations. Our results clearly reveal that O. aculeatum in free-ranging animals have a higher genetic variation than those in semi-wild animals, demonstrating that O. aculeatum is circulating naturally in wildlife and zoonotic transmission is possible. Further studies should be conducted to better understand the epidemiology and dynamics of Oesophagostomum transmission between humans, non-human primates and other wild species and livestock in Southeast Asia.

Vegetation correlates of gibbon density in the peat-swamp forest of the Sabangau catchment, Central Kalimantan, Indonesia.

Understanding the complex relationship between primates and their habitats is essential for effective conservation plans. Peat-swamp forest has recently been recognized as an important habitat for the Southern Bornean gibbon (Hylobates albibarbis), but information is scarce on the factors that link gibbon density to characteristics of this unique ecosystem. Our aims in this study were firstly to estimate gibbon density in different forest subtypes in a newly protected, secondary peat-swamp forest in the Sabangau Catchment, Indonesia, and secondly to identify which vegetation characteristics correlate with gibbon density. Data collection was conducted in a 37.1 km(2) area, using auditory sampling methods and vegetation "speed plotting". Gibbon densities varied between survey sites from 1.39 to 3.92 groups/km(2). Canopy cover, tree height, density of large trees and food availability were significantly correlated with gibbon density, identifying the preservation of tall trees and good canopy cover as a conservation priority for the gibbon population in the Sabangau forest. This survey indicates that selective logging, which specifically targets large trees and disrupts canopy cover, is likely to have adverse effects on gibbon populations in peat-swamp forests, and calls for greater protection of these little-studied ecosystems.