Primate conservation: Lessons learned in the last 20 years can guide future efforts

Effects of protected area coverage and research on conservation status of primates globally

Conducting conservation research and establishing protected areas (PAs) based on research results are critical to biodiversity conservation. However, the effect of research and PAs on conservation of threatened species has rarely been evaluated simultaneously. We collected data on PAs from 2000 for 2021 and determined the number of publications on global primates (published from 1950 to 2021) to assess the effect of PAs, research, and biological and socioeconomic factors on the current International Union for Conservation of Nature endangered status and change in status. We used the MCMCglmm package to conduct a phylogenetic comparative analysis to control the phylogenetic relationship of primate species. The status of 24.6% (82 of 333) of species assessed at least twice declined. Only the black lion tamarin (Leontopithecus chrysopygus) had an improved status. Species with status declines mostly occurred on the south coast of West Africa and in Madagascar. PAs covered 22.1% of each species' range. Forest loss in PAs (5.5%) was significantly lower than forest loss within 5 km outside PAs (13.8%), suggesting PAs effectively mitigated forest loss. Both the median number of total publications and conservation publications on critically endangered species were higher than those of other categories. Models showed that PA coverage and number of publications or conservation-focused publications were not related to current status or change in status over time. A decline in status was not related to creation of PAs or increase of research since the last assessment. Our results suggest that current PAs and research are not reversing the extinction crisis of global primates. Doing more conservation-oriented research, strengthening management of current PAs, and expanding PAs will be needed to protect primates globally.

Behavioral thermoregulation in primates: A review of literature and future avenues

Primates face severe challenges from climate change, with warming expected to increase animals' thermoregulatory demands. Primates have limited long-term options to cope with climate change, but possess a remarkable capacity for behavioral plasticity. This creates an urgency to better understand the behavioral mechanisms primates use to thermoregulate. While considerable information exists on primate behavioral thermoregulation, it is often scattered in the literature in a manner that is difficult to integrate. This review evaluates the status of the available literature on primate behavioral thermoregulation to facilitate future research. We surveyed peer-reviewed publications on primate thermoregulation for N = 17 behaviors across four thermoregulatory categories: activity budgeting, microhabitat use, body positioning, and evaporative cooling. We recorded data on the primate taxa evaluated, support for a thermoregulatory function, thermal variable assessed, and naturalistic/manipulative study conditions. Behavioral thermoregulation was pervasive across primates, with N = 721 cases of thermoregulatory behaviors identified across N = 284 published studies. Most genera were known to utilize multiple behaviors (x ¯  = 4.5 ± 3.1 behaviors/genera). Activity budgeting behaviors were the most commonly encountered category in the literature (54.5% of cases), while evaporative cooling behaviors were the least represented (6.9% of cases). Behavioral thermoregulation studies were underrepresented for certain taxonomic groups, including lemurs, lorises, galagos, and Central/South American primates, and there were large within-taxa disparities in representation of genera. Support for a thermoregulatory function was consistently high across all behaviors, spanning both hot- and cold-avoidance strategies. This review reveals asymmetries in the current literature and avenues for future research. Increased knowledge of the impact thermoregulatory behaviors have on biologically relevant outcomes is needed to better assess primate responses to warming environments and develop early indicators of thermal stress.

Population status of proboscis monkeys in Balikpapan Bay and their potential survival challenges in Nusantara, the proposed new capital city of Indonesia

Populations of rare and endangered species are nowadays in peril due to large-scale habitat conversion, and even sizeable and stable populations are confronted with unexpected challenges. We conducted a full census of a proboscis monkey (Nasalis larvatus) population in Balikpapan Bay and located 292 one-male-multifemale units and 67 all-male units in 2022. Using data on average group size, subsampled from Balikpapan Bay, we estimated a total population size of 3907 individuals. The rate of proboscis monkey habitat loss in Balikpapan Bay has been slowing down to the current 0.69% per year. It is predicted that habitat recovery may exceed habitat loss after 13 years. The Indonesian capital city relocation was announced in 2019 with spatial plans designed to cover a total land area of 2,560 km2 across various habitats until 2045. A total number of 1449 individuals (37.08% of the population) were found on 80.55 km2 (41.29%) of habitat that overlapped with current spatial plans of Nusantara Capital city. The construction work just started; before that, the government had already claimed it would be a "smart, green, beautiful, and sustainable city". We, therefore, include our recommendations to mitigate the impact of the construction and to pursue the goal to construct the most sustainable capital city, concerning local biodiversity and thus become a pioneer in a new direction of proboscis monkey conservation.

Healing Hanuman's Army: Veterinary Care as a Core Component of One Health Principles in a Southeast Asian Monkey Forest

Wildlife that inhabit urban landscapes face the dual challenge of negotiating their positions in their group while navigating obstacles of anthropogenically modified landscapes. The dynamics of urban environments can result in novel injuries and mortalities for these animals. However, these negative impacts can be mitigated through planning, and onsite veterinary care like that provided by the Ubud Monkey Forest in Bali, Indonesia. We examined 275 recorded injuries and mortalities among six social groups of long-tailed macaques (Macaca fascicularis) brought to the veterinary clinic from 2015-2018. We fit the probabilities of injury vs. death among macaques brought to the clinic using a multilevel logistic regression model to infer the relationship between injury vs. death and associated demographic parameters. Males were more likely to sustain injuries and females were more likely to die. The frequency of injuries and mortalities changed over the four-year study period, which was reflected in our model. The odds of mortality were highest among young macaques and the odds of injury vs. mortality varied across the six social groups. We categorized injuries and mortalities as "natural" or "anthropogenic". Most injuries and mortalities were naturally occurring, but powerlines, motorized vehicles, and plastic present ongoing anthropogenic threats to macaque health. Most wounds and injuries were successfully treated, with healthy animals released back to their group. We suggest other sites with high levels of human-alloprimate interplays consider the Ubud Monkey Forest veterinary office as a model of care and potentially adopt their approaches.

Fifty+ years of primate research illustrates complex drivers of abundance and increasing primate numbers

Many primate populations are threatened by human actions and a central tool used for their protection is establishing protected areas. However, even if populations in such areas are protected from hunting and deforestation, they still may be threatened by factors such as climate change and its cascading impacts on habitat quality and disease dynamics. Here we provide a long-term and geographically wide-spread population assessment of the five common diurnal primates of Kibale National Park, Uganda. Over 7 year-long or longer census efforts that spanned 52 years, our team walked 1466 km, and recorded 480 monkey groups. Populations were generally relatively stable with a few exceptions, for which no apparent causative factors could be identified. This stability is unexpected as many ecological changes documented over the last 34+ years (e.g., decreasing food abundance and quality) were predicted to have negative impacts. Populations of some species declined at some sites but increased at others. This highlights the need for large, protected areas so that declines in particular areas are countered by gains in others. Kibale has large areas of regenerating forest and this most recent survey revealed that after 20+ years, forest regeneration in many of these areas appears sufficient to sustain sizeable primate populations, except for blue monkeys that have not colonized these areas. Indeed, the average primate abundance in the regenerating forest was only 8.1% lower than in neighboring old-growth forest. Thus, park-wide primate abundance has likely increased, despite many pressures on the park having risen; however, some areas in the park remain to be assessed. Our study suggests that the restoration, patrolling, and community outreach efforts of the Uganda Wildlife Authority and their partners have contributed significantly to protecting the park and its animals.

Primate population dynamics in Ngogo, Kibale National Park, Uganda, over nearly five decades

Many anthropogenic-driven changes, such as hunting, have clear and immediate negative impacts on wild primate populations, but others, like climate change, may take generations to become evident. Thus, informed conservation plans will require decades of population monitoring. Here, we expand the duration of monitoring of the diurnal primates at Ngogo in Kibale National Park, Uganda, from 32.9 to 47 years. Over the 3531 censuses that covered 15,340 km, we encountered 2767 primate groups. Correlation analyses using blocks of 25 census walks indicate that encounters with groups of black and white colobus, blue monkeys, and baboons neither increased nor decreased significantly over time, while encounters with groups of redtail monkeys and chimpanzees marginally increased. Encounters with mangabeys and L'Hoesti monkeys increased significantly, while red colobus encounters dramatically decreased. Detailed studies of specific groups at Ngogo document changes in abundances that were not always well represented in the censuses because these groups expanded into areas away from the transect, such as nearby regenerating forest. For example, the chimpanzee population increased steadily over the last 2 + decades but this increase is not revealed by our census data because the chimpanzees expanded, mainly to the west of the transect. This highlights that extrapolating population trends to large areas based on censuses at single locations should be done with extreme caution, as forests change over time and space, and primates adapt to these changes in several ways.

Human-modified landscapes driving the global primate extinction crisis

The world's primates have been severely impacted in diverse and profound ways by anthropogenic pressures. Here, we evaluate the impact of various infrastructures and human-modified landscapes on spatial patterns of primate species richness, at both global and regional scales. We overlaid the International Union for the Conservation of Nature (IUCN) range maps of 520 primate species and applied a global 100 km2 grid. We used structural equation modeling and simultaneous autoregressive models to evaluate direct and indirect effects of six human-altered landscapes variables (i.e., human footprint [HFP], croplands [CROP], road density [ROAD], pasture lands [PAST], protected areas [PAs], and Indigenous Peoples' lands [IPLs]) on global primate species richness, threatened and non-threatened species, as well as on species with decreasing and non-decreasing populations. Two-thirds of all primate species are classified as threatened (i.e., Critically Endangered, Endangered, and Vulnerable), with ~86% experiencing population declines, and ~84% impacted by domestic or international trade. We found that the expansion of PAST, HFP, CROP, and road infrastructure had the most direct negative effects on primate richness. In contrast, forested habitat within IPLs and PAs was positively associated in safeguarding primate species diversity globally, with an even stronger effect at the regional level. Our results show that IPLs and PAs play a critical role in primate species conservation, helping to prevent their extinction; in contrast, HFP growth and expansion has a dramatically negative effect on primate species worldwide. Our findings support predictions that the continued negative impact of anthropogenic pressures on natural habitats may lead to a significant decline in global primate species richness, and likely, species extirpations. We advocate for stronger national and international policy frameworks promoting alternative/sustainable livelihoods and reducing persistent anthropogenic pressures to help mitigate the extinction risk of the world's primate species.

Sustaining Traditional Ethnomedicinal Knowledge and Protected Areas in Synergy: A Case Study of Overa-Aru Wildlife Sanctuary in Kashmir Himalaya

The ethnic communities living near protected areas are critically dependent on medicinal plants for their healthcare. Although several ethnomedicinal studies are available from the Himalaya, quantitative studies focusing on protected areas in this region are largely overlooked. In this study, we aimed to document the ethnomedicinal plants of the Overa-Aru wildlife sanctuary in Kashmir Himalaya. We conducted a systematic field survey in the study area during 2020 - 2021 to collect primary data from 110 participants through semi-structured interviews and questionnaires. The data was analyzed using quantitative indices and Pearson's correlation. We recorded 64 plant species used against 8 human disease categories, including some first-time reports from the region. Asteraceae and Lamiaceae were the most dominant families and herbs were the dominant growth form. The most common plant part used were leaves, and the main method of preparation was decoction. Plant species with the highest relative frequency of citation was Achillea millifolium (0.83). Informant consensus factor for each disease category ranged from 0.94 to 0.97. We found a strong positive correlation between participants' age and citations (r = 0.85), but a negative correlation between the participants' education status and citations (r = - 0.11). Our results revealed that the younger generation possesses the least ethnomedicinal information. We recommend that the species with high use values and fidelity level merit priority in phytochemical and pharmaceutical studies. Our findings highlight that protected areas, besides their prime importance in biodiversity conservation, play a pivotal role in providing the healthcare provisioning ecosystem services to the ethnic communities.

Population dynamics of western gorillas at Mbeli Bai

Long-term studies of population dynamics can provide insights into life history theory, population ecology, socioecology, conservation biology and wildlife management. Here we examine 25 years of population dynamics of western gorillas at Mbeli Bai, a swampy forest clearing in Nouabalé-Ndoki National Park, the Republic of Congo. The Mbeli population more than doubled from 101 to 226 gorillas during the study. After adjusting for a net influx of gorillas into the study population, the increase represents an inherent growth rate of 0.7% per year, with 95% confidence limits between -0.7% and 2.6%. The influx of gorillas mainly involved immigration of individuals into existing study groups (social dispersal), but it also included the appearance of a few previously unknown groups (locational dispersal). The average group size did not change significantly during the study, which is consistent with the possibility that western gorillas face socioecological constraints on group size, even when the population is increasing. We found no significant evidence of density dependence on female reproductive success or male mating competition. The distribution of gorillas among age/sex categories also did not change significantly, which suggests that the population had a stable age structure. Our results provide evidence of population stability or growth for some western gorillas (albeit within a small area). The results highlight the value of law enforcement, long-term monitoring, and protected areas; but they do not diminish the importance of improving conservation for this critically endangered species.

Factors influencing terrestriality in primates of the Americas and Madagascar

Among mammals, the order Primates is exceptional in having a high taxonomic richness in which the taxa are arboreal, semiterrestrial, or terrestrial. Although habitual terrestriality is pervasive among the apes and African and Asian monkeys (catarrhines), it is largely absent among monkeys of the Americas (platyrrhines), as well as galagos, lemurs, and lorises (strepsirrhines), which are mostly arboreal. Numerous ecological drivers and species-specific factors are suggested to set the conditions for an evolutionary shift from arboreality to terrestriality, and current environmental conditions may provide analogous scenarios to those transitional periods. Therefore, we investigated predominantly arboreal, diurnal primate genera from the Americas and Madagascar that lack fully terrestrial taxa, to determine whether ecological drivers (habitat canopy cover, predation risk, maximum temperature, precipitation, primate species richness, human population density, and distance to roads) or species-specific traits (body mass, group size, and degree of frugivory) associate with increased terrestriality. We collated 150,961 observation hours across 2,227 months from 47 species at 20 sites in Madagascar and 48 sites in the Americas. Multiple factors were associated with ground use in these otherwise arboreal species, including increased temperature, a decrease in canopy cover, a dietary shift away from frugivory, and larger group size. These factors mostly explain intraspecific differences in terrestriality. As humanity modifies habitats and causes climate change, our results suggest that species already inhabiting hot, sparsely canopied sites, and exhibiting more generalized diets, are more likely to shift toward greater ground use.

Proyecto Titi: Teaching children that cotton‐top tamarins ( Saguinus oedipus ) are not appropriate pets

Cotton-top tamarins (Saguinus oedipus) are a critically endangered species found only in Colombia. Their survival is threatened by extensive habitat destruction and the illegal pet trade. Because many people in Colombia have a low level of awareness of cotton-top tamarins and even less understanding of the impacts that the illegal pet trade has on the species and its long-term survival, Proyecto Tití has developed a series of programs for children in rural elementary schools that introduce children to cotton-top tamarins. This study examines Proyecto Titi's efforts to reduce the desire to have a cotton-top tamarin as a pet with outcomes focused specifically on (1) creating an emotional connection between people and cotton-top tamarins, (2) identifying the feelings and understanding the challenges that cotton-top tamarin face when they are kept as pets, and (3) empowering students to make positive choices to help cotton-top tamarins. Both TITI KIDS and TITIRITIANDO programs helped students to (1) increase their knowledge of cotton-top tamarins, (2) understand the damage that the pet trade has on individual animals and the long-term survival of cotton-top tamarins and (3) provide practical actions that they can engage in to protect cotton-top tamarins for the future. Our hope is that students from our programs become advocates for conservation in their communities and assist in the long-term conservation activities to protect cotton-top tamarins in Colombia.

Social media’s potential to promote conservation at the local level: an assessment in eleven primate range countries

Historically, Internet access has been linked to a country’s wealth. However, starting a decade ago, this situation changed dramatically and Internet access became increasingly available in primate range countries. The rapid growth of smartphone use in developing nations has created new avenues to communicate conservation. Here we assess the potential of social media to promote primate conservation at the local level within primate range countries. We interviewed 381 people in communities associated with 18 conservation projects from 11 countries to assess their use of social media. We found that 91% of the people had at least one social media account and 95% of these people checked their accounts daily. The median number of contacts per person across all platforms was 453 and 300 considering only each person’s most used platform. We also documented that local conservation projects had a diversity of information they wanted to relay to the local community through social media. Our research highlights the potential for social media to be an extremely useful communication tool for tropical conservation scientists. Thus, we encourage more conservation groups to explore using social media to communicate to local communities and to report on the impact it has on conservation.

Accessibility to Protected Areas Increases Primate Hunting Intensity in Bioko Island, Equatorial Guinea

Bioko is one of the most important sites for African primate conservation; yet it has seen a severe decline in its primate populations due to illegal hunting to supply a thriving wildmeat trade. The completion in 2015 of a new road bisecting the Gran Caldera Scientific Reserve (GCSR), where rugged terrain and lack of infrastructure once served as a natural barrier, further threatened this last stronghold for Bioko's primates. Here we used passive acoustic monitoring to study factors affecting hunting patterns within GCSR through the automatic detection of shotgun sounds. Ten acoustic sensors were placed in locations that varied in terrain heterogeneity, distance to the new road, human settlements, research camps (i.e., Moraka and Moaba) and elevation. Sensors recorded continuously between January 2018 and January 2020, collecting 2,671 site-days of audio. In total 596 gunshots were detected, including in the most remote areas. There were significant differences in hunting rate between areas (Kruskal-Wallis, χ2 = 102.71, df = 9, p < 0.001). We also found there were significantly fewer gunshots during 2019 than during 2018 (V = 55, p < 0.001). Occupancy modeling showed that hunting increased with decreasing terrain heterogeneity and decreasing distance to roads and villages; and decreased with increasing proximity to Research Camps. These results demonstrated that increasing accessibility increased primate hunting in GCSR, which was exacerbated by the opening of the new road. We also demonstrated that research presence was effective at reducing primate hunting. Unless strict conservation interventions are implemented, including road checkpoints, increasing biomonitoring and hunting patrols, and an island-wide, enforced ban on firearms, GCSR will see a significant decrease in primate density over the next decade, including the potential extinction of Critically Endangered Pennant's red colobus, whose entire population is restricted to GCSR and is a primary target of hunters.