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Concept: Geoffroy's Spider Monkey


Animal home ranges may vary little in their size and location in the short term but nevertheless show more variability in the long term. We evaluated the degree of site fidelity of two groups of spider monkeys (Ateles geoffroyi) over a 10- and 13-year period, respectively, in the northeastern Yucatan peninsula, Mexico. We used the Local Convex Hull method to estimate yearly home ranges and core areas (defined as the 60% probability contour) for the two groups. Home ranges varied from 7.7 to 49.6 ha and core areas varied from 3.1 to 9.2 ha. We evaluated the degree of site fidelity by quantifying the number of years in which different areas were used as either home ranges or core areas. Large tracts were used only as home ranges and only for a few years, whereas small areas were used as either core area or home range for the duration of the study. The sum of the yearly core areas coincided partially with the yearly home ranges, indicating that home ranges contain areas used intermittently. Home ranges, and especially core areas, contained a higher proportion of mature forest than the larger study site as a whole. Across years and only in one group, the size of core areas was positively correlated with the proportion of adult males in the group, while the size of home ranges was positively correlated with both the proportion of males and the number of tree species included in the diet. Our findings suggest that spider monkey home ranges are the result of a combination of long-term site fidelity and year-to-year use variation to enable exploration of new resources.

Concepts: Time, Primate, Term, Atelidae, Home range, Spider monkey, Geoffroy's Spider Monkey, Black-headed Spider Monkey


The presentation of food may affect feeding competition and the well-being of captive social species. We hypothesized that feeding competition in a captive group of 5 black-handed spider monkeys (Ateles geoffroyi) should increase in response to certain food presentations in terms of size, distribution and quality of food, and that higher feeding competition should lead to an increase in agonism and physiological stress (measured by faecal glucocorticoid metabolites, FGCM) as well as to a decrease in affiliation, proximity among individuals and feeding activity. We used 5 experimental treatments representing different combinations of size, distribution and quality of food. We observed social interactions for 100 h, collected 6,500 proximity and feeding activity records, and gathered 226 faecal samples. When food was clumped, individuals spent less time feeding, and there was also significant individual variation in feeding activity within treatments. FGCM levels were higher when food was clumped. These results are probably linked to an increase in feeding competition when food is concentrated. At least in small groups of spider monkeys, dispersing food in two feeding stations may be sufficient to decrease differences among individuals in priority of access to food resources, hence reducing physiological stress and interindividual differences in feeding activity.

Concepts: Primate, Hypothesis, Stress, Presentation, Atelidae, Spider monkey, Geoffroy's Spider Monkey, Black-headed Spider Monkey


Studies of the gut microbiome have become increasingly common with recent technological advances. Gut microbes play an important role in human and animal health, and gut microbiome analysis holds great potential for evaluating health in wildlife, as microbiota can be assessed from non-invasively collected fecal samples. However, many common fecal preservation protocols (e.g. freezing at -80°C) are not suitable for field conditions, or have not been tested for long-term (greater than 2 weeks) storage. In this study, we collected fresh fecal samples from captive spider monkeys (Ateles geoffroyi) at the Columbian Park Zoo (Lafayette, IN, USA). The samples were pooled, homogenized, and preserved for up to 8 weeks prior to DNA extraction and sequencing. Preservation methods included: freezing at -20°C, freezing at -80°C, immersion in 100% ethanol, application to FTA cards, and immersion in RNAlater. At 0 (fresh), 1, 2, 4, and 8 weeks from fecal collection, DNA was extracted and microbial DNA was amplified and sequenced. DNA concentration, purity, microbial diversity, and microbial composition were compared across all methods and time points. DNA concentration and purity did not correlate with microbial diversity or composition. Microbial composition of frozen and ethanol samples were most similar to fresh samples. FTA card and RNAlater-preserved samples had the least similar microbial composition and abundance compared to fresh samples. Microbial composition and diversity were relatively stable over time within each preservation method. Based on these results, if freezers are not available, we recommend preserving fecal samples in ethanol (for up to 8 weeks) prior to microbial extraction and analysis.

Concepts: Bacteria, Biotechnology, Primate, Food preservation, Atelidae, Spider monkey, Geoffroy's Spider Monkey, Black-headed Spider Monkey


We analyzed the effect of human visitors on the behavior of a group of spider monkeys (Ateles geoffroyi) kept on a small tourist island. Although the spider monkey is a common species in zoos, there are very few specific studies on visitor effects on these monkeys. We conducted behavioral observations on the group of spider monkeys to evaluate the effect of visitors. We also used actimetry devices to measure the variations in the spider monkeys' locomotor activity associated with human presence. With regard to the effect on behavior, we found an increase in self-directed behaviors and a decrease in vocalization, both associated with human presence. Moreover, our results suggest that when people feed monkeys, there is an increase in agonistic behaviors. On the other hand, we found that changes in activity levels in response to human presence vary among individuals. We conclude that changes in spider monkeys' behavior could provide evidence of the negative effect of visitors in our study conditions. Although we discuss the differences in activity levels due to differences in social position, further research is required this topic. Our results can be used to inform management plans for this species in captivity. Improving this relationship between humans and non-human primates through tourism education programs would benefit ecotourism and therefore species conservation programs.

Concepts: Psychology, Human, Primate, Behavior, Atelidae, Spider monkey, Geoffroy's Spider Monkey, Black-headed Spider Monkey


The physiological mechanisms that allow for sleeping in a vertical position, which is primordial for arboreal primates, have not been studied yet.

Concepts: Sleep, Electroencephalography, Primate, Atelidae, Spider monkey, Geoffroy's Spider Monkey, Arboreal theory, Black-headed Spider Monkey


The vertebral heart score (VHS) is a method of evaluation of cardiac size well documented in domestic mammals and in other primate species, and the aim of this study was to determine the VHS in three species of Spider monkey.

Concepts: Human, Heart, Mammal, Primate, Atelidae, Spider monkey, Geoffroy's Spider Monkey, Black-headed Spider Monkey


Resting by primates is considered an understudied activity, relative to feeding or moving, despite its importance in physiological and time investment terms. Here we describe spider monkeys' (Ateles geoffroyi) travel from feeding to resting trees in a seasonal tropical forest of the Yucatan Peninsula. We followed adult and subadult individuals for as long as possible, recording their activities and spatial location to construct travel paths. Spider monkeys spent 44% of the total sampling time resting. In 49% of the cases, spider monkeys fed and subsequently rested in the same tree, whereas in the remaining cases they travelled a mean distance of 108.3 m. Spider monkeys showed high linear paths (mean linearity index = 0.77) to resting trees when they travelled longer distances than their visual field, which suggests travel efficiency and reduced travel cost. Resting activity is time consuming and affects the time available to search for food and engage in social interactions.

Concepts: Primate, Rainforest, Atelidae, Spider monkey, Geoffroy's Spider Monkey, Brown Spider Monkey, Atelinae, Black-headed Spider Monkey


The rapid loss, fragmentation and degradation of tropical forests threaten the survival of many animal species. However, the way in which these phenomena affect animal health has been poorly explored, thus limiting the design of appropriate conservation strategies. To address this, here we identified using linear mixed models the effect of proximal (diet, activity pattern, hunting and logging) and distal (sum of the basal areas of fruiting-tree species [SBAFS], landscape forest cover and degree of forest fragmentation) variables over fecal glucocorticoid metabolite (fGCM) levels-hormones associated with animal health and fitness-of six groups of spider monkeys (Ateles geoffroyi) inhabiting six landscapes with different spatial structures in Mexico. Proximal variables showed a stronger predictive power over fGCMs than distal. In this sense, increases in travel time, the occurrence of hunting, and reductions in rest time and fruit consumption resulted in higher fGCM levels. Regarding distal variables, increases in SBAFS were negatively related to fGCM levels, thus suggesting that food scarcity increases stress hormone levels. Nevertheless, contrary to theoretical expectations, spider monkeys living in smaller tracts of forest spent less time travelling, but the same time feeding on fruit as those in more forested areas. The lower net energy return associated with this combination of factors would explain why, contrary to theoretical expectations, increased forest cover was associated with increased levels of fGCMs in these groups. Our study shows that, at least in the short term, spider monkeys in fragmented landscapes do not always present higher levels of stress hormones compared to those inhabiting continuous forest, and the importance of preserving fruit sources and controlling hunting for reducing the levels of stress hormones in free ranging spider monkeys.

Concepts: Time, Forest, Primate, Tropical rainforest, Atelidae, Spider monkey, Geoffroy's Spider Monkey, Black-headed Spider Monkey


Two species of pinworms, Trypanoxyuris atelis and T. atelophora were collected from the black-handed spider monkey (Ateles geoffroyi) in several localities across southeastern Mexico, representing the first record for both species in Mexican primates. Identification of pinworm species was based on morphological and molecular data. These pinworms are distinguished from other congeners, and from each other, by the buccal structure, the lateral alae, and the morphology of the oesophagus. Phylogenetic analyses based on sequences of the mitochondrial cytochrome c oxidase subunit 1 gene placed T. atelis as the sister species of T. minutus, a parasite of the howler monkey Alouatta palliata, and T. atelophora as the sister species of T. microon, a parasite of the night monkey, Aotus azarae. These relationships were supported with high posterior probability values by Bayesian inference. Comparisons of additional pinworm taxa from Neotropical primates are needed to assess oxyurid diversity, and to better understand the evolutionary relationships among these nematodes and their primate hosts.

Concepts: Primate, Howler monkey, Atelidae, New World monkey, Spider monkey, Geoffroy's Spider Monkey, Atelinae, Black-headed Spider Monkey