Primates最新文献

Food selection in primates is guided by a sensory evaluation of the physical and chemical properties of the foods. These properties vary with plant species, plant part, and plant maturity. Spider monkeys generally consume ripe fruits, but their diet also includes unripe fruits and young and mature leaves from a wide variety of plant species. We evaluated food selection in ten adult black-handed spider monkeys (Ateles geoffroyi) living in a controlled environment in Catemaco (Veracruz, Mexico). We used six plant species which are part of their natural diet and compared selection between ripe and unripe fruits and young and mature leaves, respectively, for the same plant species. We also analyzed the sucrose content, pH, size, and color of fruits and the color and size of leaves of each plant species. For fruit selection, our model showed that 75% of choices depended on an association between the plant species and the stage of maturity. In contrast, our model predicted 52% of the leaf selection, and monkeys considered both the stage of maturity and the plant species. Our results suggest that Ateles geoffroyi exhibit a more specific food selection for fruits than leaves, resulting in different food choices based on the physical and chemical properties of these food items.

The influence of gut microbiota on vertebrate health, development, growth, and physiology is increasingly evident. Considerable research has concentrated on Primates, not only because many non-human species have long acted as laboratory models to better understand human health, but also to improve our knowledge of the ecology of this mammalian Order with the highest proportion of endangered wild taxa. While bacteria have been the primary focus, other gut components (archaea, protozoa, fungi, viruses, and helminths) also play critical roles in host survival. Only recently have there been microbiota studies examining interactions among gut components and their influence in both captive and wild non-human primates. Here we systematically reviewed all research articles on non-human primates where gut bacteria were studied together with at least one other gut taxon. Studies on humans were included in each comparison where these suggested (i) potential health outcomes of patterns observed in non-human primates, or (ii) how approaches used in human microbiota studies could more effectively advance non-human primate research and conservation. Specifically, we focused on associations (such as covariations in diversity indices or abundance between taxa), direct interactions (one taxon affecting another with experimental evidence), and external influences (e.g., disease, diet, environment) impacting multiple taxa. We found that for non-human primates, direct interactions among bacteria and other gut taxa have rarely been confirmed except under experimental captive conditions, especially for wild species. However, the associated changes in richness, abundance, and/or metabolic pathways indicate interdependence among gut taxa, confirming their links with host nutrition and immunity and, consequently, their potential impact on host health and species conservation.

The study of animal activity budgets provides information regarding species' behavioural repertoire and how this can change over various time scales and due to external factors, both natural and anthropogenic. External environmental factors affecting animal behaviour vary on temporal and spatial scales, and include fluctuations in daily weather patterns, annual and long-term climatic variability, and the spatial and temporal distribution of resources, as well as inter- and intra-specific interactions. We present the results from the first long-term, 10 years, study of activity budgets of the Critically Endangered yellow tailed woolly monkey (Lagothrix flavicauda), a species endemic to high elevation forests in northern and central Peru. Our study took place at the El Toro field station which lies on the eastern slopes of the Andes in the Comunidad Campesina de Yambrasbamba in Amazonas Region, Peru. We collected behavioural data using instantaneous sampling on focal individuals. We analysed a total of 18,440 instantaneous samples, covering 3,073 h of survey effort, across 65 months between October 2009 and November 2018. Overall activity budgets for L. flavicauda were 30.3% 'Travel', 29.3% 'Rest', 27.7% 'Feed', 9.6% 'Forage', 1.5% 'Social' and 1.7% 'Other' behaviours. Our results are similar to the previously published activity budget for L. flavicauda at the site, and comparisons with other woolly monkeys show similar tendencies. There were significant differences in behaviours between age/sex classes with adult males resting more, juveniles the most social, and females foraging most. There was a trend of more foraging and resting during the dry season. We found lower incidences of resting and increased social behaviours correlated with higher minimum temperatures, and reduced social behaviour with increased precipitation. Better understanding of primate behavioural ecology and adaptability to temporal changes in environmental conditions and resource availability can help improve conservation strategies.

Establishing clear, rationales for conservation actions is critical to optimizing the chances of rescuing threatened species worldwide. We propose a simple habitat suitability index, a trade-off between occupancy probability and extinction risk, to guide conservation actions for the blond capuchin monkey (Sapajus flavius), whose distribution spans the contrasting but adjacent Atlantic Forest and Caatinga phytogeographic domains of northeastern Brazil. Our objective was to create a map to spatially coordinated management options considering both domains under two divergent but plausible scenarios assuming contrasting conservation outcomes: (1) active conservation efforts, in which government agencies/communities agree to invest and participate in conservation actions; and (2) no intervention and no additional effort. Based on the habitat suitability index, sites were classified into three types: A (protected and suitable, n = 3); B (suitable but under high extinction risk, n = 9); and C (unsuitable and highly defaunated, n = 75). Our results show that under Scenario 1 it would be possible to fund an active taskforce to improve forest quality in habitat remnant types B and C while supporting monitoring and protection of type-A sites. However, little can be done under Scenario 2 without successful educational programs to raise awareness and change the perception of local stakeholders. This study introduces a spatial index to prioritise conservation actions at key sites, providing a practical approach to effective resource management in a changing environment. Our protocol may be useful in guiding conservation action in the face of resource constraints and rapid environmental and climatic change in increasingly threatened biodiversity hotspots.

Endemic to the Atlantic Forest, Callithrix aurita faces endangerment due to habitat loss, fragmentation, and yellow fever epidemics, exacerbated by the introduction of non-native marmoset species, which heightens the risk of competition, hybridization, and genetic erosion. In this study, we employed playback methods and occupancy models to investigate habitat use by C. aurita and hybrid marmoset groups (Callithrix spp.) across 15 forest fragments in Guidoval, state of Minas Gerais, Brazil. We examined the influence of forest connectivity and distance from Guidoval's urban center on the occupancy of both C. aurita and Callithrix spp. We also assessed the influence of fragment size on their detection probability. Our findings revealed a mean occupancy probability of 0.65 for C. aurita and 0.83 for Callithrix spp. Interestingly, C. aurita occupancy correlated negatively with distance from Guidoval's urban center, possibly due to historical fragmentation processes that provided protection to certain groups in closer, less invaded fragments. Conversely, Callithrix spp. occupancy showed no correlation with any variable, highlighting their adaptability and raising concerns about their potential to threaten native species through hybridization and substitution. Additionally, fragment size did not influence detection probability of both taxa, this implies that the sampled areas may not be large enough for this variable to have an effect. Overall, our results underscore the urgent need for conservation efforts to mitigate the impacts of habitat fragmentation and invasive species on endangered marmoset populations in the Atlantic Forest.

The home range represents the space in which individuals of a determined species carry out their essential activities and is influenced by ecological and behavioural factors. Accurate estimates of a given home range are essential for understanding the spatial requirements of a species and for developing effective conservation strategies. Therefore, this study aimed to estimate and characterise the minimum home range of a group of blonde capuchin monkeys (Sapajus flavius) in a Caatinga dry forest in northeastern Brazil, using tool-use sites as spatial indicators. Between November 2023 and December 2024, 370 stone tool sites with evidence of recurrent use (presence of food remains) were recorded and georeferenced using handheld GPS, posteriorly confirmed by camera traps. Based on these stone tool sites, the home range of the group was delineated using the minimum convex polygon method with 100% of the locations. The size of the minimum home range was 53.7 ha; the majority of the home range consisted of Savannah Formations (67.7%, 36.35 ha), followed by anthropogenic areas (27.6%, 14.9 ha). We conclude that lithic sites can serve as an alternative indicator for spatial estimates of blonde capuchin home ranges in contexts where direct observation is difficult. Furthermore, human-modified areas in the home range may reduce the availability of food resources and consequently, stone tool use sites. Our results provide the first home range estimate for blonde capuchins in the Caatinga dry forest and highlight the need to improve habitat quality.

The Gulf of Guinea rainforests, renowned for exceptional primate endemism, are increasingly fragmented and face severe hunting-induced defaunation. However, the long-term persistence of primate assemblages in these hunted forests remains understudied. The unprotected Ebo-Ndokbou-Makombe landscape, designated the Yabassi Key Biodiversity Area (YKBA), represents one of the region's largest remaining forest tracts, yet its primate community is largely unexplored. Research and conservation efforts within this landscape predominantly focus on the Ebo block to protect its cryptic gorilla population, while Ndokbou and Makombe receive less attention. Here, we assess the persistence and polyspecific assemblages of diurnal primates across the three forest blocks. From January to December 2019, we surveyed over 1,500 km of reconnaissance walks and sighted seven IUCN Threatened and one Near-Threatened species, including chimpanzees Pan troglodytes ellioti (56 groups and 296 nest groups), putty-nosed monkeys Cercopithecus nictitans (435 groups), crowned monkeys C. pogonias (251), red-eared monkeys C. erythrotis (122), mona monkeys C. mona (108), Preuss's monkeys Allochrocebus preussi (97), red-capped mangabeys Cercocebus torquatus (40), and drills Mandrillus leucophaeus (20). Notably, over 40% of primate encounters were polyspecific groups with up to five species. Despite conservation focus on Ebo, encounter rates, association patterns, and group sizes were comparable across Ebo, Ndokbou, and Makombe. Interestingly, primate encounter rates and assemblages in this unprotected landscape were also similar to observations in Korup National Park located within the same ecoregion. These findings underscore the critical conservation value of the YKBA and call for urgent landscape-scale interventions to mitigate hunting pressure and maintain habitat integrity.

The perineal organ of male red colobus monkeys (Piliocolobus tephrosceles) is illustrated with photographs. I discuss its possible role as a mimic of female genitalia and how thereby it may play a role in social relations between adult and juvenile males and ultimately in the reproductive success of males. This is one of the few examples of a monkey species in which the male perineal anatomy appears to mimic the female external genitalia, contrary to the pattern in many New World monkey species that have hypertrophied clitorises possibly mimicking a penis or scrotum. Furthermore, I emphasize that when one can recognize this organ and distinguish it from the external genitalia of females, more refined demographic data are obtained, particularly so as it relates to when age-related changes in sex ratio occur.

Anthropogenic noise may affect the spectral and temporal structures of contact calls in wild non-human primates. However, most studies have compared groups living at varying distances from noise sources, while few have focused on the relationship between specific noise types and vocalizations at the individual level, which is necessary to examine vocal plasticity. We aimed to clarify the effects of background noise on the acoustic characteristics of coo calls of Japanese macaques on an individual basis; thus, we examined the effects of noise levels, behavioral context, and number of individuals in proximity on the duration and spectral measure of calls. We conducted focal observations of adult female Japanese macaques, and recorded coo calls and background noise levels. We analyzed 128 calls from nine subjects and found that the start and mean frequencies of coo calls were higher at higher noise levels. The call duration and frequency modulations were higher when the number of individuals in proximity was lower and the end frequency was higher during foraging and moving. These findings suggest that different factors affect the acoustic characteristics of the coo calls of Japanese macaques simultaneously. The most intense background noise sources were typically low-frequency sources that overlapped the frequency bands of the calls. Hence, they exerted a profound influence on call acoustics, which is consistent with the results of previous studies. Within-individual adjustments to ambient noise indicate vocal plasticity, enabling efficient signal transmission to the receiver.