Evaluating expert-based habitat suitability information of terrestrial mammals with GPS-tracking data.

Aim: Macroecological studies that require habitat suitability data for many species often derive this information from expert opinion. However, expert-based information is inherently subjective and thus prone to errors. The increasing availability of GPS tracking data offers opportunities to evaluate and supplement expert-based information with detailed empirical evidence. Here, we compared expert-based habitat suitability information from the International Union for Conservation of Nature (IUCN) with habitat suitability information derived from GPS-tracking data of 1,498 individuals from 49 mammal species. Location: Worldwide. Time period: 1998-2021. Major taxa studied: Forty-nine terrestrial mammal species. Methods: Using GPS data, we estimated two measures of habitat suitability for each individual animal: proportional habitat use (proportion of GPS locations within a habitat type), and selection ratio (habitat use relative to its availability). For each individual we then evaluated whether the GPS-based habitat suitability measures were in agreement with the IUCN data. To that end, we calculated the probability that the ranking of empirical habitat suitability measures was in agreement with IUCN's classification into suitable, marginal and unsuitable habitat types. Results: IUCN habitat suitability data were in accordance with the GPS data (> 95% probability of agreement) for 33 out of 49 species based on proportional habitat use estimates and for 25 out of 49 species based on selection ratios. In addition, 37 and 34 species had a > 50% probability of agreement based on proportional habitat use and selection ratios, respectively. Main conclusions: We show how GPS-tracking data can be used to evaluate IUCN habitat suitability data. Our findings indicate that for the majority of species included in this study, it is appropriate to use IUCN habitat suitability data in macroecological studies. Furthermore, we show that GPS-tracking data can be used to identify and prioritize species and habitat types for re-evaluation of IUCN habitat suitability data.

Infant adoptions in wild bonnet macaques (Macaca radiata).

Though uncommon, adoption of orphaned infants has been observed in both wild and captive non-human primates. In two groups of wild bonnet macaques (Macaca radiata), we observed five instances of infants being cared for after they lost their mothers at a pre-weaning age (< 6 months). Orphaned infants had one or more caregivers (juvenile, subadult, and adult female or male) involved in carrying, grooming, hugging, and protecting them. Adoption did not appear to be related to the age/sex class of the infant, or directly to the mother's rank. Although the dominance rank of the mother of an orphaned infant did not have a direct effect on orphan survivorship, it determined the number of caregivers available to the orphaned infant, and infant survivorship was positively related to the number of caregivers of the orphaned infant. Thus, survivorship was likely a function of the mother's sociality. Two other infants born to high-ranking mothers were also adopted by more individuals and survived longer than the infants of low-ranking mothers.

Titi monkey neophobia and visual abilities allow for fast responses to novel stimuli.

The Snake Detection Theory implicates constricting snakes in the origin of primates, and venomous snakes for differences between catarrhine and platyrrhine primate visual systems. Although many studies using different methods have found very rapid snake detection in catarrhines, including humans, to date no studies have examined how quickly platyrrhine primates can detect snakes. We therefore tested in captive coppery titi monkeys (Plecturocebus cupreus) the latency to detect a small portion of visible snake skin. Because titi monkeys are neophobic, we designed a crossover experiment to compare their latency to look and their duration of looking at a snake skin and synthetic feather of two lengths (2.5 cm and uncovered). To test our predictions that the latency to look would be shorter and the duration of looking would be longer for the snake skin, we used survival/event time models for latency to look and negative binomial mixed models for duration of looking. While titi monkeys looked more quickly and for longer at both the snake skin and feather compared to a control, they also looked more quickly and for longer at larger compared to smaller stimuli. This suggests titi monkeys' neophobia may augment their visual abilities to help them avoid dangerous stimuli.

Influence of rainfall on sleeping site choice by a group of anubis baboons (Papio anubis).

For diurnal nonhuman primates, shifting among different sleeping sites may provide multiple benefits such as better protection from predators, reduced risk of parasitic infection, and closer proximity to spatially and temporally heterogeneous food and water. This last benefit may be particularly important in sleeping site selection by primates living in savanna-woodlands where rainfall is more limited and more seasonally pronounced than in rainforests. Here, we examined the influence of rainfall, a factor that affects food and water availability, on the use of sleeping sites by anubis baboons (Papio anubis) over two 13-month study periods that differed in rainfall patterns. We predicted that during wet periods, when food and water availability should be higher, the study group would limit the number of sleeping sites and would stay at each one for more consecutive nights than during dry periods. Conversely, we predicted that during dry periods the group would increase the number of sleeping sites and stay at each one for fewer consecutive nights as they searched more widely for food and water. We also predicted that the group would more often choose sleeping sites closer to the center of the area used during daytime (between 07:00 and 19:00) during wet months than during dry months. Using Global Positioning System data from collared individuals, we found that our first prediction was not supported on either monthly or yearly timescales, although past monthly rainfall predicted the use of the main sleeping site in the second study period. Our second prediction was supported only on a yearly timescale. This study suggests that baboons' choice of sleeping sites is fluid over time while being sensitive to local environmental conditions, one of which may be rainfall.

Effects of body size on estimation of mammalian area requirements.

Accurately quantifying species' area requirements is a prerequisite for effective area-based conservation. This typically involves collecting tracking data on species of interest and then conducting home-range analyses. Problematically, autocorrelation in tracking data can result in space needs being severely underestimated. Based on the previous work, we hypothesized the magnitude of underestimation varies with body mass, a relationship that could have serious conservation implications. To evaluate this hypothesis for terrestrial mammals, we estimated home-range areas with global positioning system (GPS) locations from 757 individuals across 61 globally distributed mammalian species with body masses ranging from 0.4 to 4000 kg. We then applied block cross-validation to quantify bias in empirical home-range estimates. Area requirements of mammals <10 kg were underestimated by a mean approximately15%, and species weighing approximately100 kg were underestimated by approximately50% on average. Thus, we found area estimation was subject to autocorrelation-induced bias that was worse for large species. Combined with the fact that extinction risk increases as body mass increases, the allometric scaling of bias we observed suggests the most threatened species are also likely to be those with the least accurate home-range estimates. As a correction, we tested whether data thinning or autocorrelation-informed home-range estimation minimized the scaling effect of autocorrelation on area estimates. Data thinning required an approximately93% data loss to achieve statistical independence with 95% confidence and was, therefore, not a viable solution. In contrast, autocorrelation-informed home-range estimation resulted in consistently accurate estimates irrespective of mass. When relating body mass to home range size, we detected that correcting for autocorrelation resulted in a scaling exponent significantly >1, meaning the scaling of the relationship changed substantially at the upper end of the mass spectrum.

Efectos del Tamaño Corporal sobre la Estimación de los Requerimientos de Área de Mamíferos Resumen La cuantificación precisa de los requerimientos de área de una especie es un prerrequisito para que la conservación basada en áreas sea efectiva. Esto comúnmente implica la recolección de datos de rastreo de la especie de interés para después realizar análisis de la distribución local. De manera problemática, la autocorrelación en los datos de rastreo puede resultar en una subestimación grave de las necesidades de espacio. Con base en trabajos previos, formulamos una hipótesis en la que supusimos que la magnitud de la subestimación varía con la masa corporal, una relación que podría tener implicaciones serias para la conservación. Para probar esta hipótesis en mamíferos terrestres, estimamos las áreas de distribución local con las ubicaciones en GPS de 757 individuos de 61 especies de mamíferos distribuidas mundialmente con una masa corporal entre 0.4 y 4,000 kg. Después aplicamos una validación cruzada en bloque para cuantificar el sesgo en estimaciones empíricas de la distribución local. Los requerimientos de área de los mamíferos <10 kg fueron subestimados por una media ∼15% y las especies con una masa ∼100 kg fueron subestimadas en ∼50% en promedio. Por lo tanto, encontramos que la estimación del área estaba sujeta al sesgo inducido por la autocorrelación, el cual era peor para las especies de talla grande. En combinación con el hecho de que el riesgo de extinción incrementa conforme aumenta la masa corporal, el escalamiento alométrico del sesgo que observamos sugiere que la mayoría de las especies amenazadas también tienen la probabilidad de ser aquellas especies con las estimaciones de distribución local menos acertadas. Como corrección, probamos si la reducción de datos o la estimación de la distribución local informada por la autocorrelación minimizan el efecto de escalamiento que tiene la autocorrelación sobre las estimaciones de área. La reducción de datos requirió una pérdida de datos del ∼93% para lograr la independencia estadística con un 95% de confianza y por lo tanto no fue una solución viable. Al contrario, la estimación de la distribución local informada por la autocorrelación resultó en estimaciones constantemente precisas sin importar la masa corporal. Cuando relacionamos la masa corporal con el tamaño de la distribución local, detectamos que la corrección de la autocorrelación resultó en un exponente de escalamiento significativamente >1, lo que significa que el escalamiento de la relación cambió sustancialmente en el extremo superior del espectro de la masa corporal.

Capture, immobilization, and Global Positioning System collaring of olive baboons (Papio anubis) and vervets (Chlorocebus pygerythrus): Lessons learned and suggested best practices.

As the value of Global Positioning System (GPS) technology in addressing primatological questions becomes more obvious, more studies will include capturing and collaring primates, with concomitant increased risk of adverse consequences to primate subjects. Here we detail our experiences in capturing, immobilizing, and placing GPS collars on six olive baboons (Papio anubis) in four groups and 12 vervet monkeys (Chlorocebus pygerythrus) in five groups in Kenya. We captured baboons with cage traps and vervets with box traps, immobilized them, and attached GPS collars that were to be worn for 1 year. Adverse consequences from the trapping effort included incidental death of two nonsubjects (an adult female and her dependent infant), temporary rectal prolapse in one baboon, superficial wounds on the crown of the head in two vervets, and failure to recapture/remove collars from two baboons and two vervets. Obvious negative effects from wearing collars were limited to abrasions around the neck of one vervet. A possible, and if so, serious, adverse effect was greater mortality for collared adult female vervets compared with known uncollared adult female vervets, largely due to leopard (Panthera pardus) predation. Collared animals could be more vulnerable to predation because trapping favors bolder individuals, who may also be more vulnerable to predation, or because collars could slow them down or make them more noticeable to predators. Along with recommendations made by others, we suggest that future studies diversify trapping bait to minimize the risk of rectal prolapse, avoid capturing the first individuals to enter traps, test the movement speeds of collared versus noncollared animals, include a release system on the collars to avoid retrapping failure, and publish both positive and negative effects of capturing, immobilizing, and collaring.

Complete rectal prolapse in wild anubis baboons (Papio anubis).

This report describes two cases of rectal prolapse in wild anubis baboons (Papio anubis), with one spontaneous resolution. Both occurred after individuals consumed low-water, high-fibre dried maize during provisioning prior to capture, while one also experienced distress during capture.

Assessing Transmission of Antimicrobial-Resistant Escherichia coli in Wild Giraffe Contact Networks.

There is growing evidence that anthropogenic sources of antibiotics and antimicrobial-resistant bacteria can spill over into natural ecosystems, raising questions about the role wild animals play in the emergence, maintenance, and dispersal of antibiotic resistance genes. In particular, we lack an understanding of how resistance genes circulate within wild animal populations, including whether specific host characteristics, such as social associations, promote interhost transmission of these genes. In this study, we used social network analysis to explore the forces shaping population-level patterns of resistant Escherichia coli in wild giraffe (Giraffa camelopardalis) and assess the relative importance of social contact for the dissemination of resistant E. coli between giraffe. Of 195 giraffe sampled, only 5.1% harbored E. coli isolates resistant to one or more tested antibiotics. Whole-genome sequencing on a subset of resistant isolates revealed a number of acquired resistance genes with linkages to mobile genetic elements. However, we found no evidence that the spread of resistance genes among giraffe was facilitated by interhost associations. Giraffe with lower social degree were more likely to harbor resistant E. coli, but this relationship was likely driven by a correlation between an individual's social connectedness and age. Indeed, resistant E. coli was most frequently detected in socially isolated neonates, indicating that resistant E. coli may have a selective advantage in the gastrointestinal tracts of neonates compared to other age classes. Taken together, these results suggest that the maintenance of antimicrobial-resistant bacteria in wild populations may, in part, be determined by host traits and microbial competition dynamics within the host.IMPORTANCE Antimicrobial resistance represents a significant threat to human health, food security, and the global economy. To fully understand the evolution and dissemination of resistance genes, a complete picture of antimicrobial resistance in all biological compartments, including natural ecosystems, is required. The environment and wild animals may act as reservoirs for anthropogenically derived resistance genes that could be transferrable to clinically relevant bacteria of humans and domestic animals. Our study investigated the possible transmission mechanisms for antimicrobial-resistant bacteria within a wild animal population and, more broadly, contributes to our understanding of how resistance genes are spread and maintained in natural ecosystems.

Male-inflicted wounds have opposite effects on hair cortisol for captive male and female rhesus macaques (Macaca mulatta) following new group formation.

Sexual dimorphism in body size, aggression, and dispersal patterns may affect the degree to which males and females perceive aggression from either sex as stressful. Whereas male macaques typically disperse to new groups at maturity, thus encountering many unfamiliar individuals of both sexes, females are philopatric, usually only encountering unfamiliar males who transfer into their natal groups. In rare circumstances, however, group fusions can expose both males and females to many novel individuals, which often increases aggression. Here, we use a captive new group formation of rhesus macaques (Macaca mulatta) as a model of social instability during fusions and examine differences in male and female chronic stress responses to male-pattern and female-pattern trauma (i.e., trauma inflicted by males or by females, respectively). We found that male- but not female-pattern traumas predicted hair cortisol concentrations during the first 9 months after new group formation, but in opposite ways for males and females. A greater number of male-pattern traumas was linked to elevated hair cortisol concentrations in females but slightly lower hair cortisol concentrations in males. We suggest that the apparent importance of male-pattern trauma, but not female-pattern-trauma, in predicting higher hair cortisol concentrations in females can be attributed to the more acutely intense but less persistent nature of male aggression toward females.

The role of sleeping sites in the predator-prey dynamics of leopards and olive baboons.

Predation is widely recognized as an important selective pressure on prey animals such as baboons (Papio spp.), which face high leopard (Panthera pardus) predation risk, particularly at night. Baboons regularly sleep on cliff faces and in trees at night, ostensibly to avoid such predators. Despite retreating to such "refuges," baboons are most often killed by leopards at or near their sleeping sites. Because of the challenges of studying nocturnal behavior and human-averse predators, few systematic data exist to reveal how leopard ranging near baboon sleeping sites influences baboons' selection of sites and behavior at those sites. To investigate leopard-baboon dynamics at sleeping sites we deployed GPS/VHF radio collars on six representatives of four baboon groups and four leopards during a 14-month field study in Kenya. We used locations recorded every 15 min to identify baboons' cliffside and riverine sleeping sites, the frequency and duration of leopard visits to these sites, and baboons' adjustments in site use after leopard visits. Collared leopards visited riverine sites more frequently than cliffside sites, whereas most baboon groups strongly preferred cliffside sites, suggesting that leopard visits were often due to factors other than baboon presence, and that baboons used cliffside sites to reduce their risk of leopard predation. Regardless of type, collared leopards remained near baboon-occupied sleeping sites longer than vacant ones, indicating interest in hunting baboons then. Baboons at riverine sites departed later on mornings after leopard visits. Baboon groups occasionally shared sleeping sites simultaneously, possibly reducing risk through dilution. However, they did not reduce risk by frequently changing sleeping sites, minimizing detection at sleeping sites, or after leopard visits, arriving earlier the next evening or moving to a different site. Future research should explore if baboons readily detect nocturnal leopard presence and if predation-related changes in sleeping site use have cascading ecological effects.

Coping style and cortisol levels in infancy predict hair cortisol following new group formation in captive rhesus macaques (Macaca mulatta).

Social instability in primate groups has been used as a model to understand how social stress affects human populations. While it is well established that individual cercopithecines have different temperaments or personalities, little is known about how temperament mediates the experience of social instability in large, naturalistic groups. Here, we report findings from a study tracking a newly formed group of captive rhesus macaques (Macaca mulatta). We examine whether inter-individual differences in temperament during infancy affect physiological responses to new group formation years later, measured through hair cortisol 9 months after the group was formed. Our results show that early life measures of temperament characteristics predict later-life hypothalamic-pituitary-adrenal activity following new group formation, though not always in the directions we predicted. Individuals with higher blood cortisol concentrations in response to a novel stressor and lower blood cortisol concentrations following a Dexamethasone Suppression Test in infancy had lower hair cortisol values following new group formation later in life. Individuals characterized in infancy as more emotional or more active exhibited lower hair cortisol profiles 9 months after group formation. We suggest that these two temperament characteristics, emotionality and activity, may represent two different mechanisms leading to low hair cortisol values. That is, the physiological measure of low hair cortisol may have two different meanings depending on temperament characteristics of the individual. Our results demonstrate that temperament and physiological responsiveness measures in infancy can predict individual responses to a new group formation years later.

GPS-identified vulnerabilities of savannah-woodland primates to leopard predation and their implications for early hominins.

Predation is thought to have been a key selection pressure in primate evolution, especially in the savannah-woodland habitats where several early hominin species lived. However, predator-primate prey relationships are still poorly understood because human presence often deters predators, limiting our ability to quantify the impact of predation. Synchronized high-resolution tracking of leopards (Panthera pardus), vervets (Chlorocebus pygerythrus), and olive baboons (Papio anubis) during a 14-month study in Kenya revealed that increased vulnerability to leopard predation was not associated with higher encounter rates, smaller body size, smaller group size, or greater distance from refuges, contrary to long-standing inferences. Instead, the initiation, rate, timing, and duration of encounters, outcome of approaches, and predation events showed only a diel pattern of differential vulnerability. In the absence of human observers, vervets were more vulnerable during the day, whereas baboons were more vulnerable at night, but overall neither species was more vulnerable than the other. As our results show that leopards avoided baboons during the day and hunted them at night, we suggest that the same pattern would have applied to hominins-because they were even larger than baboons and bipedal, resulting in similarly offensive capability on the ground during the day but poorer agility in the trees at night, especially as they became committed bipeds. Drawing from hominid behavior and archaeopaleontological and ethnographic evidence, we hypothesize that ground-sleeping hominins initially dealt with this formidable threat by using stone tools to modify Acacia branches into 'bomas', thorny enclosures that provided nighttime shelter. The ability of hominins to create their own nightly refuges on the ground wherever Acacia spp. were available would have allowed them to range more widely, a crucial step in furthering the spread of hominins across Africa and beyond.

Moving in the Anthropocene: Global reductions in terrestrial mammalian movements.

Animal movement is fundamental for ecosystem functioning and species survival, yet the effects of the anthropogenic footprint on animal movements have not been estimated across species. Using a unique GPS-tracking database of 803 individuals across 57 species, we found that movements of mammals in areas with a comparatively high human footprint were on average one-half to one-third the extent of their movements in areas with a low human footprint. We attribute this reduction to behavioral changes of individual animals and to the exclusion of species with long-range movements from areas with higher human impact. Global loss of vagility alters a key ecological trait of animals that affects not only population persistence but also ecosystem processes such as predator-prey interactions, nutrient cycling, and disease transmission.

GPS-identified, low-level nocturnal activity of vervets (Chlorocebus pygerythrus) and olive baboons (Papio anubis) in Laikipia, Kenya.

OBJECTIVES: Except for owl monkeys (Aotus spp.), all anthropoid primates are considered strictly diurnal. Recent studies leveraging new technologies have shown, however, that some diurnal anthropoids also engage in nocturnal activity. Here we examine the extent to which vervets (Chlorocebus pygerythrus) and olive baboons (Papio anubis) are active at night. MATERIALS AND METHODS: We deployed GPS collars with tri-axial accelerometer data loggers on 18 free-ranging adult females: 12 vervets spread among 5 social groups, and 6 olive baboons spread among 4 groups. Their locations were recorded every 15 min, and their activity levels, for 3 s/min over 7.5 months. We also used camera traps that were triggered by heat and movement at seven sleeping sites. RESULTS: Travel was detected on 0.4% of 2,029 vervet-nights involving 3 vervets and 1.1% of 1,109 baboon-nights involving 5 baboons. Travel was mainly arboreal for vervets but mainly terrestrial for baboons. During the night, vervets and baboons were active 13% and 15% of the time, respectively. Activity varied little throughout the night and appeared unaffected by moon phase. DISCUSSION: Our results confirm the low nocturnality of vervets and olive baboons, which we suggest is related to living near the equator with consistent 12-hr days, in contrast to other anthropoids that are more active at night. Since anthropoid primates are thought to have evolved in northern latitudes, with later dispersal to tropical latitudes, our results may have implications for understanding the evolution of anthropoid diurnality.

Delayed Dispersal and Immigration in Equatorial Sakis (Pithecia aequatorialis): Factors in the Transition from Pair- to Group-Living.

Saki monkeys (Pithecia spp.) live in pairs and small groups, sometimes with more than 1 same-sex adult. Previous studies have not been able to distinguish additional, unrelated adults from adult-sized offspring, but both can influence social relationships and mating strategies, albeit in different ways. In this study, we documented the immigration of an adult male equatorial saki (P. aequatorialis) into a group following the departure of the previous resident male. At immigration, the group contained an adult female, her 5-year-old (adult age) and 1.5-year-old daughters, and her 1-month-old infant. We used nearest neighbor, approach, grooming, playing, aggression, and copulation data to describe the social dynamics between the immigrant male and the 2 adult females. In the 12 months following his arrival, the immigrant male tended to be closer to and groom the adult daughter more than the mother, but he mated with both females. Both females interacted more with the immigrant male than with each other, and both females eventually reproduced. These observations provide evidence that in equatorial sakis, adult offspring may delay dispersal and reproduce within their natal group, thus transitioning from groups of reproductive pairs to groups with more than 1 reproductive adult of the same sex.

Snake scales, partial exposure, and the Snake Detection Theory: A human event-related potentials study.

Studies of event-related potentials in humans have established larger early posterior negativity (EPN) in response to pictures depicting snakes than to pictures depicting other creatures. Ethological research has recently shown that macaques and wild vervet monkeys respond strongly to partially exposed snake models and scale patterns on the snake skin. Here, we examined whether snake skin patterns and partially exposed snakes elicit a larger EPN in humans. In Task 1, we employed pictures with close-ups of snake skins, lizard skins, and bird plumage. In task 2, we employed pictures of partially exposed snakes, lizards, and birds. Participants watched a random rapid serial visual presentation of these pictures. The EPN was scored as the mean activity (225-300 ms after picture onset) at occipital and parieto-occipital electrodes. Consistent with previous studies, and with the Snake Detection Theory, the EPN was significantly larger for snake skin pictures than for lizard skin and bird plumage pictures, and for lizard skin pictures than for bird plumage pictures. Likewise, the EPN was larger for partially exposed snakes than for partially exposed lizards and birds. The results suggest that the EPN snake effect is partly driven by snake skin scale patterns which are otherwise rare in nature.

Fast Detector/First Responder: Interactions between the Superior Colliculus-Pulvinar Pathway and Stimuli Relevant to Primates.

Primates are distinguished from other mammals by their heavy reliance on the visual sense, which occurred as a result of natural selection continually favoring those individuals whose visual systems were more responsive to challenges in the natural world. Here we describe two independent but also interrelated visual systems, one cortical and the other subcortical, both of which have been modified and expanded in primates for different functions. Available evidence suggests that while the cortical visual system mainly functions to give primates the ability to assess and adjust to fluid social and ecological environments, the subcortical visual system appears to function as a rapid detector and first responder when time is of the essence, i.e., when survival requires very quick action. We focus here on the subcortical visual system with a review of behavioral and neurophysiological evidence that demonstrates its sensitivity to particular, often emotionally charged, ecological and social stimuli, i.e., snakes and fearful and aggressive facial expressions in conspecifics. We also review the literature on subcortical involvement during another, less emotional, situation that requires rapid detection and response-visually guided reaching and grasping during locomotion-to further emphasize our argument that the subcortical visual system evolved as a rapid detector/first responder, a function that remains in place today. Finally, we argue that investigating deficits in this subcortical system may provide greater understanding of Parkinson's disease and Autism Spectrum disorders (ASD).

Scales drive detection, attention, and memory of snakes in wild vervet monkeys (Chlorocebus pygerythrus).

Predatory snakes are argued to have been largely responsible for the origin of primates via selection favoring expansion of the primate visual system, and even today snakes can be deadly to primates. Neurobiological research is now beginning to reveal the mechanisms underlying the ability of primates (including humans) to detect snakes more rapidly than other stimuli. However, the visual cues allowing rapid detection of snakes, and the cognitive and ecological conditions contributing to faster detection, are unclear. Since snakes are often partially obscured by vegetation, the more salient cues are predicted to occur in small units. Here we tested for the salience of snake scales as the smallest of potential visual cues by presenting four groups of wild vervet monkeys (Chlorocebus pytherythrus) with a gopher snake (Pituophis catenifer) skin occluded except for no more than 2.7 cm, in natural form and flat, the latter to control for even small curvilinear cues from their unusual body shape. Each of these treatments was preceded by a treatment without the snakeskin, the first to provide a baseline, and the second, to test for vigilance and memory recall after exposure to the snakeskin. We found that (1) vervets needed only a small portion of snakeskin for detection, (2) snake scales alone were sufficient for detection, (3) latency to detect the snakeskin was longer with more extensive and complex ground cover, and (4) vervets that were exposed to the snakeskin remembered where they last saw "snakes", as indicated by increased wariness near the occluding landmarks in the absence of the snakeskin and more rapid detection of the next presented snakeskin. Unexpectedly, adult males did not detect the snakeskin as well as adult females and juveniles. These findings extend our knowledge of the complex ecological and evolutionary relationships between snakes and primates.

Snakes elicit earlier, and monkey faces, later, gamma oscillations in macaque pulvinar neurons.

Gamma oscillations (30-80 Hz) have been suggested to be involved in feedforward visual information processing, and might play an important role in detecting snakes as predators of primates. In the present study, we analyzed gamma oscillations of pulvinar neurons in the monkeys during a delayed non-matching to sample task, in which monkeys were required to discriminate 4 categories of visual stimuli (snakes, monkey faces, monkey hands and simple geometrical patterns). Gamma oscillations of pulvinar neuronal activity were analyzed in three phases around the stimulus onset (Pre-stimulus: 500 ms before stimulus onset; Early: 0-200 ms after stimulus onset; and Late: 300-500 ms after stimulus onset). The results showed significant increases in mean strength of gamma oscillations in the Early phase for snakes and the Late phase for monkey faces, but no significant differences in ratios and frequencies of gamma oscillations among the 3 phases. The different periods of stronger gamma oscillations provide neurophysiological evidence that is consistent with other studies indicating that primates can detect snakes very rapidly and also cue in to faces for information. Our results are suggestive of different roles of gamma oscillations in the pulvinar: feedforward processing for images of snakes and cortico-pulvinar-cortical integration for images of faces.

A Saki Saga: Dynamic and Disruptive Relationships among Pithecia aequatorialis in Ecuador.

Saki monkeys live in socially monogamous groups and in groups containing more than one same-sex adult. As part of a 10-year study of equatorial sakis (Pithecia aequatorialis) in Ecuador, we documented the immigration of a second adult male into a group containing a resident male-female pair that had associated with one another for seven years and the resident female's two daughters. In the first month after immigration, the resident male spent more time closer to and grooming his putative adult daughter than the resident female, and the two males were seen performing a cooperative territorial display. After two months, the resident male interacted more with the resident female than with his putative adult daughter, while that daughter interacted more with the immigrant male and copulated with him. After three months, the males left the group together and associated with an unfamiliar female, leaving the resident females and a neonate behind. The resident male then paired with a new female, while the immigrant male joined another group, again as a second male. Compared to other socially monogamous primates, sakis appear to have a more variable social system whereby additional males can join established groups and form relationships with putatively unrelated males.