Behaviours of animals in captivity tend to differ from those in the wild. This is particularly true for nocturnal species, which are often kept indoors under reversed light cycles. Knowledge of Africa's slow-moving nocturnal primates, the pottos, in captivity is lacking and wild data of the three currently recognised species are scarce. Perodicticus edwardsi, the only species studied for more than a year in the wild, lives in social pairs, spending a third of their time together during the active period, alongside sharing sleeping sites. We investigated the activity budgets and substrate use of two individuals (a female with a tail, light brown pelage and facial markings, a male with no tail, dark pelage and facial markings) at Birmingham Wildlife Conservation Park, United Kingdom. We collected data from June to August 2024 between 10:00 h and 16:00 h via 5-minute focal instantaneous sampling, totalling 240 hours. We observed 43 of 55 behaviours, suggesting that the captive environment was suitably enriching. Despite being in a relatively small enclosure, pottos spent an average of 17% of their activity in social interactions. No race walk and less bridging was observed in the study individuals as seen in other lorisids. To stimulate those behaviours, those keeping this genus in captivity need to provide interconnected bridges in the form of ropes or rubber tubes in enclosures.
The study of sleeping site selection in primates is fundamental to the development of appropriate conservation strategies. Here we present data on the characteristics and usage of sleeping sites of the northern sportive lemurs (Lepilemur septentrionalis) at Montagne des Français, Madagascar. The study was conducted on three individuals over a period of seven months from December 2018 to June 2019. The research objective is to describe the sleeping site characteristics and usage patterns of L. septentrionalis in the dry forest of Montagne des Français. The northern sportive lemurs in this study used three types of sleeping sites: tree holes, vine tangles, and branches. Among the tree species used as sleeping sites by L. septentrionalis, Strychnos madagascariensis was used most frequently, and most of these sleeping sites were food trees. We most often observed L. septentrionalis using tall trees with large diameters at breast height. Tree holes are generally found in living trees rather than in dead or partially dead trees. We observed a significant difference in the frequency of sleeping sites reuse, with repeated use of tree holes being particularly noticeable. There is no variation in distance between the different types of sleeping sites and the first or last feeding trees. The results of this study suggest that L. septentrionalis depends primarily on large trees with tree holes. The reuse of sleeping sites may serve as a strategy for predator avoidance or for easy access to food resources, while the use of food trees as sleeping sites may be a strategy to reduce the cost of travel to access food resources. Sampling efforts must be considered to better understand the sleeping sites selection preferences of this species.
Anthropogenic climate change poses an ongoing major threat to Earth's biodiversity and is predicted to accelerate species extinctions. Primates in particular are considered highly vulnerable to changing temperature, precipitation, and seasonality characteristics. The Kenya coast dwarf galago (Paragalago cocos) and the Zanzibar dwarf galago (P. zanzibaricus) are two closely related nocturnal primates that are endemic to coastal lowland and submontane humid forest environments of eastern Kenya and Tanzania. This region of East Africa is predicted to become hotter under future climate change trajectories, and other similarly distributed species in the Paragalago genus are predicted to either lose considerable habitat or become significantly more exposed to weather extremes. In this study, we modeled how future climate change will impact climatic habitat suitability and potential distributions across the ranges of P. cocos and P. zanzibaricus under different models of atmospheric circulation and emissions pathways. We also assessed the degree of suitable habitat extents within protected areas and anthropogenic modification characteristics under climate change trajectories. Overall, climate change is predicted to have a negligible impact on future suitability. Protected areas will encompass a limited degree of suitable habitat under current and future climatic conditions. Most of the climatically suitable habitat predicted for both species occurs in heavily modified landscapes with little intact high canopy forest, and future climate change will not lead to any major changes in the composition of modified habitat in either species' ranges. Future studies should examine more localized abundance and habitat use patterns for both species, particularly in more modified habitats.
Aye-ayes possess an unusual suite of morphological characteristics that are used to locate and extract xylophagous invertebrates. A growing body of evidence supports the long-held claim that xylophagous invertebrates comprise a significant portion of aye-aye diets; however, several aye-aye features are also used to harvest endosperm from seeds of Canarium spp., another important aye-aye resource. Using continuous focal animal sampling, we collected feeding data on a female aye-aye in Madagascar's Ihofa Forest from January 2016 to December 2017 to better elucidate resource preference. We used aye-aye feeding traces in woody substrates as a proxy for xylophagous invertebrate presence to estimate xylophagous invertebrate abundance along 20 transects (10 m × 100 m). During observational follows, we also counted each trace made during feeding. Using the same transects, we also estimated Canarium seed abundance based on fruit in the canopy and fruit on the ground. There were more aye-aye feeding traces in woody substrates for xylophagous invertebrates (3206) than for Canarium seeds (2153). A Wilcoxon signed-rank test found no significant difference in the number of xylophagous invertebrates and Canarium seeds consumed during this study ( p = 0.317); however, a two-item preference index indicated that xylophagous invertebrates were the preferred resource monthly and annually. Our results indicated that the aye-aye in this study preferentially consumed xylophagous invertebrates. This provides further evidence that the aye-aye's highly derived morphology is specifically adapted for extracting insect larvae from structurally defended substrates. The use of some of these morphological autapomorphies for Canarium seed feeding may be an example of an exaptation.
Movement is critical for animals' dynamics and survival. However, the movement patterns of small-bodied animals (body mass <500 g) are rarely documented, given the difficulties in tracking them in their natural habitats. Here, we report the distance travelled by a small-bodied and nocturnal lemur (brown mouse lemur, Microcebus rufus) in Ranomafana National Park, southeastern Madagascar, using telemetry and tracking data ( N = 7 night-tracking from 5 individuals). We found that M. rufus travelled up to 840.41 m in one night with a maximum 1-hour step length of 502.90 m. Our data also showed that, on average, females (755.50 m) travelled further than males (381.90 m). We suggest that such long-distance movements could be a strategy to maintain their metabolic rate and budget activities, avoid predators, and/or respond to changes in food source distribution. Furthermore, such movements can have critical consequences on their ecological roles in the rainforest, contributing to the self-maintenance of diversity, health, and regeneration of the ecosystem.
Wild primates spend a significant portion of their lives in resting sites that are critical for survival, providing protection from predators and against weather extremes. The small-bodied and heterothermic dwarf lemurs (Cheirogaleus spp.) inhabit diverse environments in Madagascar, where they face high predation risk and thermoregulatory constraints. These lemurs variably use nests and tree holes as resting sites, and tree holes and underground locations as hibernacula, depending on the species and habitat. Here, we compare resting-site ecology in the sympatric Sibree's (C. sibreei) and furry-eared (C. crossleyi) dwarf lemurs at Tsinjoarivo forest. Whereas C. sibreei is an ecological specialist restricted to the cold rainforests of eastern Madagascar above 1500 m, C. crossleyi is an ecological generalist widely distributed across the eastern rainforests and forest fragments of the central highlands. We collate data collected between 2007 and 2019 on a total of 62 radio-collared dwarf lemurs tracked at different times of the year. We demonstrate that C. sibreei exclusively used tree holes as resting sites, showed greater resting-site fidelity, began hibernating earlier in the season, and only showed evidence of torpor once underground. In contrast, C. crossleyi occupied more and diverse resting sites in the active season, including tree holes, nests, and even exposed branches, and entered hibernation later, with many individuals expressing torpor while in nests, i.e., before switching to underground hibernacula. Adapted to cold rainforests, C. sibreei prioritizes resting sites with greater thermal insulation and a long, stable hibernation season of up to seven months. C. crossleyi opts for greater flexibility in both resting-site ecology and torpor expression. Although Tsinjoarivo is likely the coldest habitat occupied by C. crossleyi, perhaps pushing this species to the limits of their thermal tolerance, their ecological flexibility may give them a competitive edge over C. sibreei given ongoing habitat degradation at this site.
The species of the Macaca genus are classified into four social styles based on aggression and affiliative patterns, as well as their phylogenetic relationships. However, some studies suggest that social parameters can change under different local conditions, particularly in semi-free-ranging environments. The aim of our study was to examine whether the social parameters (aggression, affiliative behaviors and spatial distribution) of two groups of macaques in semi-free-ranging conditions aligned with their expected social styles. We studied a group of Macaca tonkeana (nine individuals), which the social style expected is high tolerant, and a group of Macaca fascicularis (nine individuals), which the social style expected is low tolerant. Our results indicated that some social parameters in these groups did not conform to the expected parameters. M. tonkeana exhibited lower tolerance than expected, while, conversely, the aggression patterns of M. fascicularis resembled more tolerant behaviors. These findings suggest that group characteristics, such as semi-free-ranging conditions, should be considered when analyzing social parameters like aggression, affiliative behavior, and spatial distribution.
Food transfer occurs when part or all of a food item is passed from one individual to another. Adult transfer of solid food to infants has been reported in 45 primate species. For aye-ayes, this behaviour was recorded in captivity where individuals were provisioned, but little is known about this behaviour in the wild. Wild aye-ayes consume hard-to-process foods that are inaccessible to infants such as wood-boring larvae embedded in trees and the endosperm of Canarium spp. seeds which are protected by a hard coat. Learning to process these food resources may be essential for aye-aye development. We used ad libitum sampling to record the social activities and behaviours of a mother and her male infant from January to December 2020 in Sangasanga Forest, Kianjavato, Madagascar. We collected in total 4 hours 57 minutes and 57 seconds of social behaviours. Over two days in December, we observed eight occurrences of the 11-month-old infant usurping Canarium sp. seeds from his mother. Our findings suggest that, due to physical limitations, the infant aye-aye primarily resorted to food transfer via theft to obtain hard-to-process food. Transfer of larvae, their main resource, was not observed, though it may occur until young aye-aye have the bite force needed to gouge holes in substrates and the coordination to retrieve and extract wood-boring larvae. Future research should explore if food transfer differs across individuals' sex, sites and type of food as well as the effects of anthropogenic disturbances on foraging.
Madagascar's lemurs are globally unique primates, yet many nocturnal taxa remain poorly studied. Among them, the eastern woolly lemur (Avahi laniger) is widespread across the island's northern and central-eastern rainforests, but little is known about its ecology outside protected areas. We surveyed 18 unprotected forests, representing about one third of the species' range, to evaluate its occurrence, population density, habitat use, and interactions with local communities. Using 97 nocturnal line transects (291.8 km of survey effort) combined with vegetation assessments and 208 interviews, we found A. laniger at all study sites. Estimated population density was 41.3 individuals/km2, which is at the lower margin of reported values for the genus. Encounter rates did not differ significantly along a gradient of forest degradation (undisturbed to highly logged primary forest), suggesting some tolerance to structural degradation. However, use of fallow-derived habitats was restricted to sites with the early successional tree Harungana madagascariensis, highlighting the importance of vertical structures and specific food plants. Morphological measurements showed no evidence of reduced body condition compared to populations in protected areas. Interviews revealed broad local knowledge of the species (73% recognition), occasional and opportunistic hunting, and low prevalence of taboos against consumption. Notably, hunting could be linked to locally reduced abundances. We demonstrate that A. laniger persists across a gradient of human-modified landscapes, if vertical forest structures and food resources remain available. Conservation strategies should therefore include forested areas not generally considered suitable for lemurs (e.g., agroforests), while strictly preventing hunting to ensure population viability under ongoing habitat fragmentation.
Sleep behaviour has been recorded for only ten percent of primate species. Here, we contribute to this literature by using videography to collect novel sleep behaviour data on captive gorillas. We measured, to our knowledge, the first ever sleep architecture preliminary baseline estimate data in a population of captive western lowland gorillas (Gorilla gorilla gorilla) at the Basel Zoo (Switzerland) over three months (n = 90 nights of observation). The results of this study showed significant differences in levels of sleep fragmentation between the one dominant male of our gorilla community and the subordinate individuals (one young male and females ranging in age) of the same community. This perhaps suggests that dominant individuals may suffer in their overall sleep quality however, because dominance and sex are confounded in this population, these patterns should be interpreted cautiously. While this result could be interpreted to be tradeoff between the requirements of sleep and group protection by the dominant silver back, the results of this study are novel and the first of its kind. Thus, while these preliminary differences raise questions about how social roles may relate to sleep behaviour in gorillas, further research with larger samples is required to understand how biological sex, dominance rank, and the interaction between the two within gorilla populations, influences sleep within gorillas.
The emergence of tolerance between distinct social groups is a central question in social evolution, with relevance to both nonhuman primates and early human societies. Ecological factors such as resource heterogeneity and social threats like bachelor male presence have each been proposed as drivers of intergroup proximity, but their combined effects remain unclear. We developed a spatially explicit agent-based model to examine how resource patchiness and bachelor threat jointly shape aggregation dynamics and intergroup tolerance among mixed-sex groups. In the model, groups forage across heterogeneous landscapes and expand their ranges with increasing patchiness. Bachelor groups move according to local resource gradients and generate location-dependent social pressure when in proximity to social groups, prompting groups to aggregate probabilistically according to threat intensity. Aggregation decisions follow a sigmoid response, and familiarity accumulates through repeated overlap or joint aggregation. Intergroup tolerance thus arises from encounter histories rather than being preprogrammed. Simulations show that resource heterogeneity promotes tolerance by increasing overlap and encounter frequency, while bachelor threat induces aggregation as a protective response. Tolerance can also emerge without consistent aggregation, provided that ecological conditions repeatedly bring groups together. When both heterogeneity and threat are high, aggregation and familiarity peak, indicating a synergistic effect. These outcomes are robust across the explored parameter space and do not require explicit coordination or cooperative intent. Our findings highlight how simple behavioural rules embedded in ecological and social contexts can yield complex intergroup outcomes, offering a general framework for understanding the evolution of intergroup tolerance in primates and humans.
Mangrove forests are highly threatened ecosystems, regarded as important habitats for many non-human primates, including tarsiers. However, for Philippine tarsiers (Carlito syrichta; formerly Tarsius syrichta), our understanding of their relationship with mangroves remains poor. Here, we explored how Philippine tarsiers used mangrove habitats by locating their sleeping sites, describing their sleeping behaviours, and estimating their home ranges. We surveyed Philippine tarsiers from 24 June to 10 July 2025 in a mangrove forest within the Del Carmen Mangrove Reserve on Siargao Island. We were able to record 44 sleeping sites from six Philippine tarsiers that were radio-tracked. The tarsiers frequently slept on screw pines, non-mangrove trees, and thickets, although they also used true mangrove species (Rhizophora sp. and Nypa fruticans) within the flooded portions of the site. Adult males were skittish and consistently slept solitarily, whereas the adult females were often accompanied by their juvenile offspring. From the three adult males we fitted with GPS tags, we estimated minimum home range sizes (±SE) of 3.16 ± 0.59 ha based on minimum convex polygons and 4.22 ± 1.34 ha based on kernel density estimates, with percentages of mangrove overlap ranging from 17.56 to 72.99%. Our observations underscore the value of mangrove habitats as potential refugia for supporting insular primate populations against predators, disturbances, and stochastic events, and as evolutionarily significant ecosystems that, along with their behavioral flexibility, possibly contributed to their dispersal across open oceans. We recommend extending ecological research of tarsiers in mangroves and integrating mangrove protection in tarsier conservation.
Tree- or branch-shaking displays have been reported in some nonhuman primate species, but large-sample studies addressing their possible functions are rare. The present study examined 842 and 72 tree-shaking (TS) displays by free-ranging male and female Japanese macaques (Macaca fuscata), respectively, recorded in and around the group's provisioned feeding site. In the mating season, TS displays performed by peripheral and non-group (i.e., non-central) males were almost always accompanied by loud vocalizations, whereas central males were less vocal. Also, non-central males rarely performed female-directed aggressive behaviours, whereas central males frequently did so. Aggression towards females by non-central males poses a potential cost, i.e. punishment by central males, whereas vocalizing to attract females appears to have few costs, if any, yet it might provide substantial reproductive benefits. By contrast, central males performed fewer TS displays with vocalizations as they were at less risk of getting punished for threatening or attacking females. In the non-mating season, almost all TS displays were performed by central males; non-central males were rarely observed in or around the feeding site in the non-mating season. TS displays in the non-mating season may help central males to reinforce their high-ranking positions. Most female TS displays were by the alpha female and her daughters in the non-mating season, their probable function also being to reinforce their high ranks.
As human populations expand and modify landscapes, interactions between wild primates and domesticated animals have become increasingly frequent. This review synthesizes literature on primate-domestic animal interactions to assess patterns across these associations and set the context for the subsequent articles in the special issue on this topic. In our review, we sampled reports of directly observed interactions published in full-length manuscripts within the last 25 years. Dogs (Canis lupus familiaris) are the most frequently reported domestic species involved in agonistic encounters with primates, often acting as predators or human-directed deterrents in agricultural settings. In a sample of 100 search results for relevant key words, most interactions that were documented involved dogs (92% of 117 interactions recorded in 15 of 16 articles), most of which were free-ranging. Habitat type (agroforest, protected area, or town) showed an association dog type (free-ranging or with a known owner), where dogs with known owners in agroforest make up the largest proportion of interactions, followed by free-ranging dogs in agroforest. The nature of interactions (agonism or neutral) associated with taxonomic group, where no strepsirrhines were involved in neutral interactions with dogs, and all interactions with cattle were neutral. Despite the impact of domestic animals on wild primate populations, systematic studies on primates and domestic animals, especially beyond canines, are often limited. To better understand the nature of anthropogenically influenced interspecies interactions, we recommend that researchers distinguish between the degree of human control domesticated animals are under, document the behavioural responses of both primates and domestic animals, and include interactions with non-canine domestic species, such as livestock.
Many primate species consume insects as part of their regular diet, yet few researchers have systematically collected them and analyzed their nutritional content. In this study, we developed protocols for collecting and analyzing prey items consumed by Weddell's saddleback tamarins (Leontocebus weddelli), focusing on Orthoptera (crickets, grasshoppers, and katydids) which have been documented to be a central component of their diet. We used five methods to collect insect prey (pitfall, sheet, water, moth trap and manual capture) at a field site in northwestern Bolivia over the course of two months. In total, we collected 1302 insect samples, which we photographed, weighed, dried, and sorted into nine taxonomic groups (Acrididoidea/Eumastacoidea, Blattodea, Cicadoidea, Gryllidae, Lepidoptera, Mantodea, Phasmatodea Proscopiidae, and Tettigoniidae). We then analyzed the samples for their macro- and micro-nutrients. We found that the manual capture method was the most effective for capturing orthopterans. Our analyses showed that the samples primarily contained crude protein (52.63-78.54 % dry matter (PCDM)), chitin (12.05-27.26 PCDM) and fat (4.63-15.6 PCDM). The samples also contained high levels of a wide variety of minerals, including iron (42-655 parts per million (ppm)), zinc (85-554 ppm), and manganese (37-1200 ppm). These results indicate that orthopterans and other Neotropical insects can serve as important sources of macro- and micronutrients for tamarins. Given the variation in nutrient content among taxa, we recommend that researchers collect and analyze insects that most closely resemble the prey consumed by their study subjects to determine their nutritional value, and not assume equivalent nutritional composition across species, higher taxa, or life stages. Given the success of using night walks with manual capture for collecting Orthopterans, we recommend that other primatologists use this method to allow for cross-site comparisons of insect nutrition.
Amongst the colobines (Colobinae subfamily), the douc langurs (Pygathrix) are known to use higher proportions of arm-swinging behavior in their locomotor repertoire. Previously, researchers have suggested the increased use of arm-swinging to be a result of habitat constraints. For example, suspensory locomotion allows animals to travel across unstable substrates, such as the terminal ends of branches, than would be possible in above branch locomotion. In this paper, we attempt to identify patterns of habitat use and arm-swinging amongst the doucs. Specifically, we predict arm-swinging will occur significantly more on horizontal substrates, in the main canopy, on branches (medium-sized substrates), and in old-growth forest. Data was recorded in the Son Tra Nature Reserve, Vietnam between November 2016 and April 2017. The monkeys were filmed and data was extracted continuously. Results indicate the red-shanked douc arm-swings more often when they are in the main part of the canopy compared to the top of the canopy, and possibly on substrates smaller than a bough. No differences were found in frequency of arm-swinging when individuals were in old versus new forest or on horizontal versus oblique substrates. The patterns of arm-swinging behavior follow patterns similar to that of spider monkeys, especially in substrate preferences. This information is critical for understanding and conserving the habitat of the critically-endangered red-shanked douc.
The Southern Lesser Bushbaby Galago moholi is a small, nocturnal, strepsirrhine primate, native to Sub-Saharan Africa. Previously considered a strict dietary specialist on tree exudates and insects, recent observations have revealed hitherto unappreciated plasticity in its feeding behaviour, encompassing fruits and even small vertebrates. While arthropods are an important seasonal component of the diet of this species, we still have little idea of the types of insect prey taken in nature, or the extent of any preferences among arthropod taxa. Here, I document behavioural observations made of G. moholi foraging at a moth trapping light on two occasions in November 2024 in Limpopo (Republic of South Africa), including details of feeding preferences and previously undocumented foraging vocalisations. To understand species-level preferences among potential insect prey, I presented an individual G. moholi with various prey types and recorded which were consumed. In addition, using male Driver Ants Dorylus helvolus, I experimentally manipulated prey items to gauge the relative importance of prey appearance, movement, and sound in determining their attractiveness to G. moholi. Lepidoptera were strongly favoured among available prey options, with increased discrimination applied to other groups such as Coleoptera and Hemiptera. Both sound and movement were important in determining predation from G. moholi. Although limited by low replication, these observations are the first to document species-level discrimination and preferences among a wide range of insect prey in wild G. moholi. Building a clearer picture of the dietary ecology of this species is vital for its conservation, and for better understanding its functional role in woodland food-webs. Future studies should seek to employ more systematic experimental approaches on captive and wild individuals (i) to clarify the traits that make different arthropod taxa suitable/attractive prey for this species, and (ii) to further explore the sensory ecology of G. moholi foraging, particularly the relative role of vision and audition.
Howler monkeys are well-known for producing long calls ("roars") as a means of long-distance communication. The ecological resource defense hypothesis posits that animals roar to defend food resources; thus monkeys should modify roaring behavior across seasons and between sites with varying food resource abundance. We investigated mantled howler monkey roaring behavior between the wet and dry seasons at a large, continuous lowland wet forest (La Selva Research Station) in northeastern Costa Rica as well as between La Selva and a nearby small forest fragment (La Suerte Biological Research Station, LSBRS). We quantified a proxy of resource abundance at each site by measuring tree diameter at breast height (DBH) and canopy cover and used all-occurrences sampling to collect data on roaring behavior. We calculated number of roars per minute, length of roar bouts, and roar bouts per hour. Number of roars per minute was significantly higher at La Selva during the wet season than the dry season. With respect to comparisons across sites, both canopy cover and DBH were significantly higher at La Selva. Correspondingly, the length of roar bouts and the number of roars per minute were significantly higher at La Selva. Roar bouts per hour, however, were significantly higher at LSBRS, which may be explained by the very high population density at LSBRS. The results for our comparison demonstrate that some features of howler monkey roaring behavior vary along with ecological conditions and that other non-ecological factors may also drive elements of roaring.
Human presence and climate constraints shaped the primate adaptation to employ behavioural strategies. In this study, we examined the relationship between the food environment (human presence and microclimate) and behavioural responses of long-tailed macaques ( Macaca fascicularis ) in secondary and mangrove forests of coastal habitats on Belitung Island, Indonesia, over six months (March-August 2023), with 509 h of total observations. The macaques were mainly frugivorous, but a small amount of human food consumption persisted in response to the presence of humans. The macaques spent more time resting and autogrooming, decreased both moving and feeding, fed more on human food, reduced mature fruit consumption, and decreased home range sizes when visitors were more present. Furthermore, higher humidity levels decreased feeding activity and reduced the consumption of mature fruit, seed, other plant matters, and water intake in macaques, whereas the frequency of their autogrooming and canopy usage increased. Rainfall and temperature did not substantially exhibit relationship with behavioural ecology of macaques, which supported other long-tailed macaque responses from several regional sites. The macaques appeared to have adapted to human presence and microclimate by employing an energy-minimizing strategy, i.e., using the least costly energy in activity and ranging behaviour in taking human resources, and shifting activity, diet, and particular strata as microhabitat selection during humidity stress. Overall, macaques exhibited a generalist primate species where their behaviour and dietary adaptation allowed them to address anthropogenic and microclimate pressure. Our findings provided valuable reports and essential data for developing conservation programs and strategies, particularly concerning the impacts of human presence and climate change on macaque behaviour.
