Biology subjects

Mundry, R.

Publications and source records attributed to Mundry, R..

At least 19 recordsLinked to original sources

bioRxiv2026

The effect of dominance rank on behavioural response to playback calls in ring-tailed lemurs (Lemur catta)

In group-living species, dominance hierarchies play a central role in shaping social dynamics, influencing both agonistic and affiliative interactions. Being able to recognise an individual's dominance rank at a distance, can reduce direct conflicts, facilitating group coordination, and mediating social cohesion. While the role of dominance in relation to aggressive or reproductive vocalizations has been well documented, its influence on affiliative contact calls, particularly in mediating group movement and social integration, remains underexplored. We conducted playback experiments with free-ranging adult ringtailed lemurs (Lemur catta) at the Affenwald Wildlife Park to investigate how dominance rank of the caller and rank differences between caller and listener affect behavioral responses. Using Generalized Linear Mixed Models (GLMMs), we analysed three response variables: vocal response, number of visual scans, and occurrence of movement. Our results revealed sex-specific effects: females exhibited increased movement following contact calls from high-ranking individuals, and tended to refrain from moving when their own rank exceeded that of the caller. In contrast, no significant effects of dominance rank were observed in males. These findings suggest that high-ranking females may play an important role in initiating group movement. This study provides insights into the role of dominance rank in mediating social coordination through contact calls and provides a foundation for further research into the role of vocal communication in maintaining group cohesion in primates.

animal behavior and cognition↗

bioRxiv2026

Expecting the unexpected: Great apes anticipate surprise in others

Humans adeptly navigate complex social environments by attempting to anticipate the actions and emotional responses of others. Although our closest ape relatives have sophisticated social cognitive abilities, we do not know whether they have a cognitive understanding of others' emotions. For the epistemic emotion surprise, a cognitive understanding would require sensitivity to an agent's belief, to reality, and to any misalignment between the two, allowing one to model the mental conditions that drive surprise. In a non-invasive eye tracking study with 31 chimpanzees and bonobos, apes showed evidence of a cognitive understanding of surprise: they detected the misalignment between an agent's belief and reality, exhibiting greater pupil dilation right before an agent encountered an unexpected outcome relative to an expected one. This suggests that apes and humans share a more complex understanding of others' mental lives than previously thought, capacities that likely evolved millions of years ago in a common ancestor.

animal behavior and cognition↗

bioRxiv2026

Copulation calls indicate fertility but do not reflect female mate competition in wild Guinea baboons

Across different modalities, signals play a core role in attracting mates and influencing mating success. In several non-human primate species, females produce calls during mating that are thought to promote male competition over receptive females. The extent to which social system characteristics modulate the function of copulation calls remains less clear. We studied copulation calls in wild Guinea baboons (Papio papio), who live in a multilevel society structured around units in which females associate and mate almost exclusively with a single male. We hypothesised that females use copulation calls as an indirect form of mate competition, with competition increasing in larger units. In addition, we hypothesised that females are more likely to mate again after calling. We analysed 6116 copulations between 2014 and 2025, involving 99 reproductively active females and 78 subadult and adult males. Females produced copulation calls in 72.7% of copulations, with large inter-individual variation. Neither unit size nor its interaction with the female's swelling size or the presence of simultaneously receptive females affected the probability of calling. A survival analysis with a subset of the data (2353 copulations) revealed no effect of calling on the latency to the next mating. Our results render the hypothesis that female Guinea baboons use calls in indirect mate competition unlikely. Yet, the probability of calling varied with sexual swelling size, suggesting that calls signal female fertility. Possibly, Guinea baboon copulation calls represent an evolutionary remnant, no longer under selective pressure, and can be considered index signals of female fertility.

animal behavior and cognition↗

bioRxiv2026

Wild chimpanzee groups increase social connectivity prior to risky collective action

Cooperation is foundational to complex sociality, yet presents profound evolutionary dilemmas - costs and benefits are rarely distributed evenly and the decision to collaborate or defect can involve a complex contextual calculus. These challenges are compounded when cooperation scales from pairs to groups. Group-level cooperation is fundamental to many species success, but how is it sustained and regulated in nature? One promising route to addressing this question is to examine how individuals reorganise their affiliative interactions in anticipation of group-level cooperation. We examine such pre-cooperative reorganisation using long-term data (2013-2018) from three neighbouring groups of wild chimpanzees at the Tai National Park, Cote dIvoire, who routinely cooperate as a collective to defend their territory against other groups. We found that chimpanzees adjusted the distribution of their social contacts in anticipation of risky and proactive territorial defence by forming more broadly connected, yet more diffuse, affiliative networks. Specifically, adult chimpanzees groomed and played with more group members on days of proactive territorial defence, and this pattern was temporally-sensitive, with increased affiliation occurring before, rather than after, the cooperative act. Chimpanzees accessed a broader range of partners through increased interaction efficiency by switching between more partners with shorter interactions per partner. This pattern suggests a shared evolutionary basis of dynamic social readjustment in preparation for group-level social dilemmas in hominids, potentially providing the foundation for the formalized systems of affiliation found in human societies.

animal behavior and cognition↗

bioRxiv2026

Maternal style does not predict infant growth and survival in wild Guinea baboons

Primate infants depend on their mothers for nursing, transportation, and survival, but also benefit from other behaviours such as contact, protection, and the mother serving as a model for social learning. During infancy, variation in maternal care ("maternal style") can have profound consequences for infant development and survival. We investigated the link between maternal style and infant growth and survival in wild Guinea baboons (Papio papio). This species lives in a tolerant social system with female-biased dispersal. We used data from N = 80 infants to assess variation in maternal style. The final statistical models comprised data from N = 50 infants for the growth analysis based on Parallel Laser Photogrammetry (PLP) measures of forearm length, and N = 63 infants for the survival analysis. To account for heterogeneity in data, we applied a recently established statistical framework that controls for variation in maternal behaviour with infant age. We found only moderate variation among mothers and no evidence for a link between maternal style and infant growth or survival. Neither infant sex, maternal age, nor NDVI variation, a measure later shown to be a poor indicator of food availability, predicted infant growth or survival. We suspect that, in this population living in a habitat with high carrying capacity, disease and predation have greater effects on infant growth and survival than maternal behaviour. Future studies should consider the interplay between infant behaviour and maternal responses in greater detail to better understand variation in early social development.

animal behavior and cognition↗

bioRxiv2025

Rapid updating of ecological information in wild Guinea baboons

Knowing where to find what kind of food when is essential for survival and reproduction. Recent links between feeding ecology and brain size have revived interest in foraging cognition as a core component in cognitive evolution. We investigated whether free-ranging Guinea baboons (Papio papio) keep track of the spatio-temporal availability of a preferred food resource, the Natal orange (Strychnos spinosa). A natural experiment, a massive wildfire that destroyed most oranges in 2019, allowed us to disentangle habitual routines from goal-directed behaviour in the baboons. The animals space-use patterns shifted significantly following the wildfire. After one single visit, they stopped going to the area during the period when Natal oranges would normally be available. In the following year, they resumed regular space-use patterns. We also assessed travel linearity, speed, and departure time from sleeping sites towards the target area with and without ripe fruit. Guinea baboons travelled more linearly, 14% faster, and ~40 minutes earlier towards the target area when S. spinosa was in season compared to when it was not. In conclusion, Guinea baboons rapidly updated their knowledge of high-value food availability and adjusted their space-use accordingly. These results underscore their capacity for flexible decision-making and goal-directed foraging.

animal behavior and cognition↗

bioRxiv2025

Age-trajectory of mother-infant relationships in wild Assamese macaques

Maternal care is ubiquitous in mammals, yet its degree and duration vary across taxa. Primate mothers provide extended care, with similar developmental transitions of the mother-infant relationship, though with different paces of change. Ecological conditions can influence the trajectory of this relationship, but data from the wild are still scarce. We used methods from growth studies to quantitatively describe the non-linear age-trajectory of the mother-infant spatial relationship, and the transition from dependent to independent feeding and locomotion in wild Assamese macaques (M. assamensis). We also explored sex differences in the development of the mother-infant relationship. We used a modified Gompertz function to model the combined effect of infant age and sex on mother and infant behaviors extracted from focal observations of 58 infants. Newborns were fully dependent on their mothers for feeding and transportation, with mothers maintaining close proximity. A transitional phase emerged between 1 and 3 months of infant age, marked by a noticeable reduction in the spatial proximity with the mother and a shift in the responsibility for the infants feeding and transportation. During the second half of infancy, the decrease in proximity time slowed down, with infants achieving near-complete locomotion independence, spending the majority of time away from their mothers and feeding independently. No sex differences were found. Our models provided a robust fit for most variables, but we recommend future exploration of alternative nonlinear functions. We interpret the early infant independence observed in our population in the context of the species reproductive strategy.

animal behavior and cognition↗

bioRxiv2025

Patterns of sleeping site use of Guinea baboon parties (Papio papio)

Sleeping site use in primates is thought to be influenced by multiple factors, including resource availability and competition, predation risk, and the risk of parasitic infection. While previous research has highlighted the importance of these factors, few studies have examined sleeping site use among multiple groups of non-territorial species with overlapping home ranges. Here, we investigated the sleeping site use of Guinea baboons (Papio papio) in Simenti, Senegal. We used locational data for four years of several baboon parties sharing the same range. We assessed the distribution of sleeping sites within the local habitat mosaic, the proximity of sleeping sites to those of co-occurring parties and the impact of food availability and predator presence at the landscape level on the distance between parties sleeping sites on the same night. We further investigated patterns of sleeping site use of parties across time. We found that the vast majority of sleeping sites were in the gallery forest along the perennial Gambia River, likely due to the availability of tall trees. Guinea baboons slept in close spatial proximity (>50m) to at least one other party regardless of food availability and predator presence. Patterns of sleeping site use showed no evidence of predator or parasite avoidance. Thus, Guinea baboons in Simenti likely use the abundantly available sleeping sites opportunistically rather than being driven by intergroup competition or strategies for predator avoidance or reduction of the risk of parasite infection.

ecology↗

bioRxiv2024

Sumatran orangutan mothers differ in the extent and trajectory of their expression of maternal behaviour

Mothers play a crucial role in the early development and survival of mammalian offspring, and differences in maternal care may differentially affect offsprings development. Whereas previous research has primarily focused on biological and socioecological factors to understand population-level variation in maternal behaviour, the individual as a source of variation remains understudied. We investigated between-individual variation in the average expression of, and plasticity in, six maternal behaviours in Sumatran orangutans, using 15 years of behavioural data. We found that mothers differed substantially in the average expression of four maternal behaviours, even after controlling for socioecological conditions, biological state characteristics, and the offsprings influence on these behaviours. Furthermore, not controlling for these confounding effects exaggerated or masked between-individual variation. Mothers also substantially differed in how they adjusted three of the maternal behaviours during offspring development, meaning that mothers differed in behavioural plasticity. Our results suggest that Sumatran orangutan mothers are constrained in the average expression of maternal behaviours and their plastic responses, potentially resulting in consistent differences among mothers, otherwise called maternal personality. Our findings highlight that individual variation around the population mean in maternal behaviour is more than noise and presents opportunities to study novel evolutionary processes that shape maternal behaviour.

animal behavior and cognition↗

bioRxiv2024

Patterns of landscape partitioning indicate low levels of resource competition among neighbouring Guinea baboon(Papio papio) parties

BackgroundAccess to critical resources, including food, water, or shelter, significantly determines individual fitness. As these resources are limited in most habitats, animals may employ strategies of landscape partitioning to mitigate the impact of direct resource competition. Territoriality may be regarded as an aggressive form of landscape partitioning but in non-territorial species, other forms exist. Animals living in groups with greater flexibility in their association patterns, such as multilevel societies with fission-fusion dynamics, may adjust their grouping and space use patterns to short-term variations in ecological conditions such as food availability, predation pressure, or the presence of conspecific groups. This flexibility may allow them to balance the costs of competition while reaping the benefits of better predator detection and defence. MethodsWe explored patterns of landscape partitioning among neighbouring Guinea baboon (Papio papio) parties in the Niokolo-Koba National Park, Senegal. Guinea baboons live in a multilevel society in which parties predictably form higher-level associations ("gangs"). We used four years of locational data from individuals equipped with GPS collars to estimate annual home ranges, home range overlap, and minimum distances between parties. We examined whether food availability and predator presence levels affected the cohesion between parties in 2022. ResultsWe found substantial home range and core area overlap among parties (33 to 100%). We found no effect of food availability or predator presence on the distance to the closest neighbouring party; the minimum distance between parties was less than 100 m on average. ConclusionsOur results suggest a low level of feeding competition between our study parties. Whether this is a general feature of Guinea baboons or particular to the situation in the Niokolo-Koba National Park remains to be investigated.

ecology↗

bioRxiv2024

Meat transfers follow social ties in the multi-level society of Guinea baboons but are not related to male reproductive success

In human foraging societies, hunting skill is often interpreted as a signal of male quality linked to his reproductive success through his ability to provision his family and community. Similarly, in some bird and insect species, males offer their mates food to indicate their quality as a provider. Among non-human primates, however, the relationship between meat sharing and reproductive success is underexplored, leaving the evolutionary origins of this phenomenon unresolved. Guinea baboons (Papio papio) are a promising model to investigate whether meat sharing signals male quality, since females choose their mates, have been shown to rely on males to catch and share prey, and are responsive to male foraging skill. We combined records of 109 meat-eating events with nine years of behavioural data to test whether males who more frequently acquired and shared meat with females had more females in their social units for longer. Contrary to our predictions, we found no evidence that females preferred males who acquired or shared meat more frequently, suggesting that meat acquisition does not function as a signal of male quality in Guinea baboons. One explanation may be the relatively low frequency of meat-eating events. Another is that females are less dependent on males for meat than previously reported. Our results revealed that nearly half (41%) of female meat intake originated from sources other than her unit male, including the first documented cases of female prey capture (11% of events). Thus, females likely apply other, more pertinent, criteria in mate choice.

animal behavior and cognition↗

bioRxiv2024

Confidence over competence: Real-time integration of social information in human continuous perceptual decision-making

Human perceptual decision-making is susceptible to social influences. To determine if and how individuals opportunistically integrate real-time social information about noisy stimuli into their judgment, we tracked perceptual accuracy and confidence in social (dyadic) and non-social (solo) settings using a novel continuous perceptual report (CPR) task with peri-decision wagering. In the dyadic setting, most participants showed a higher degree of perceptual confidence. In contrast, average accuracy did not improve compared to solo performance. Underlying these net effects, partners in a dyad exhibit mutual convergence of accuracy and confidence, benefiting less competent or confident individuals, at the expense of the better-performing partner. In conclusion, real-time social information asymmetrically shapes human perceptual decision-making, with most dyads expressing more confidence without a matching gain in overall competence.

neuroscience↗

bioRxiv2024

Choose your partner: Social evaluation of skilfulness at cooperative co-action tasks in Tonkean macaques (Macaca tonkeana)

Social evaluation - inferring individual characteristics of others from their past behaviours - is an adaptive strategy that helps to inform social decisions. However, how nonhuman primates form and use impressions about others to select their social partners strategically is still unclear. In this study, we investigated whether Tonkean macaques, Macaca tonkeana, can spontaneously use information, acquired by observation, to choose the optimal partners for cooperation in two co-action tasks from the same domain. The subjects (N=5) did not prefer to cooperate with the skilful partner compared to the unskilled partner, irrespective of the task or how much attention they paid to the partners actions solving a solo version of one task prior to the test. The probability of optimal choices did not increase through trials either, indicating no learning by experience with the partners across the 16 test trials. Our results contradict findings of previous studies that tested monkeys in different domains of competence and contexts, and thus encourage further investigation on monkeys social evaluation abilities. Our experimental design presents a promising way to investigate different contexts, the inter-individual differences, the different types of social information involved, and the cognitive mechanisms underlying social evaluation and partner selectivity in nonhuman primates.

animal behavior and cognition↗

bioRxiv2024

Ecological risk-taking across age in Barbary macaques

When foraging, animals face decisions regarding unpredictable resources and varying predation risk, in which the cost-benefit trade-off must be assessed. Life-history theory focuses on resource allocation with regard to development and suggests there should be a variation in risk-taking propensity across age, manifested by a shift in goals from gain acquisition to loss aversion over time. Consequently, we aimed to assess age-related variation in decision-making strategies under risk in Barbary macaques (Macaca sylvanus) living at "La Foret des Singes" in Rocamadour, France. We experimentally varied the perceived risk and potential gains in a 2x2 design. The high-risk stimulus was a rubber snake; the low-risk stimulus a cube with a snakeskin pattern. The high-value food reward was a peanut; the low-value food reward a popcorn. In 2022, we presented 83 subjects with one of the four possible factor combinations, and in 2023, we presented 70 individuals with the inverted combination (e.g. snake-popcorn in 2022, cube-peanut in 2023). We took each monkeys propensity to retrieve the reward as a measure of risk-taking, and the latency to retrieve the reward as motivation to engage in the risky choice. Regardless of age, subjects generally retrieved the reward when placed next to the cube, whether peanut or popcorn, but were less likely to retrieve the reward placed next to the snake when this was popcorn rather than peanut. However, older individuals were faster than younger conspecifics to retrieve the reward when it was popcorn, whether paired with the cube or snake. Our results do not comply with the notion that risk-taking propensity declines with age, but rather suggest that in this paradigm, the animals assess the costs and benefits of a risky situation across age, and that the subjective value of a resource may change with age.

animal behavior and cognition↗

bioRxiv2024

Increased female competition for males with enhanced foraging skills in Guinea baboons

Recognizing skillful group members is crucial for making optimal social choices. Whether and how nonhuman animals attribute skill to others is still debated. Using a lever-operated food box, we enhanced the foraging skill of a single male (the specialist) in one zoo housed and two wild groups of Guinea baboon (Papio papio). We measured group members behav-ioral responses before, during, and after our manipulation to reveal whether they focused on the outcome of the males actions or changed their assessment of his long-term value. During the manipulation, females in the specialists unit, but not the wider group, competed over ac-cess to the specialist - increasing their grooming of him tenfold and aggression near him four-fold. Both behaviors were predicted by the amount each female ate from the food box and re-turned to baseline within two weeks of its removal. This behavioral pattern supports an out-come-based assessment where females responded to male-provided benefits (utility) rather than attributing competence (value). TeaserGuinea baboon females monopolize males in relation to their current perceived utility.

animal behavior and cognition↗

bioRxiv2024

Maternal behavior in Sumatran orangutans (Pongo abelii) is modulated by mother-offspring characteristics and socioecological factors

Mammalian mothers flexibly invest in their offspring to maximize their lifetime fitness. Flexible maternal investment may be particularly important in large-brained species with prolonged maternal care - e.g., in great apes. We investigated the effects of socioecological factors and mother-offspring characteristics on nine maternal behaviors in wild Sumatran orangutans (Pongo abelii; N=22 mother-offspring pairs; over 11,200 hours of focal data; collected from 2007-2022) using generalized linear mixed models. The behaviors fall under four maternal functions: locomotory support (carrying), skill acquisition support (feeding in proximity, food transfer), protective proximity maintenance (body contact and proximity initiation, following), and independence promotion (body contact and proximity termination, avoiding). Mothers parity was not significantly associated with any maternal behavior. Mothers were more likely to show locomotory support, skill acquisition support, and protective proximity maintenance toward younger than older offspring; whereas they were more likely to promote independence in older than younger offspring. Mothers with male offspring were more likely to show skill acquisition support to their offspring than those with female offspring. With increasing food availability, skill acquisition support reduced. With increasing association size, mothers were more likely to show protective proximity maintenance and less likely to promote independence. When males were present, mothers were more likely to show locomotory support to their offspring. Sumatran orangutan mothers thus flexibly adjust offspring directed behavior in response to prevailing socioecological factors and mother-offspring characteristics. Our findings add support to the evolutionary theory that mammalian mothers flexibly invest in their offspring.

animal behavior and cognition↗

bioRxiv2023

Overcoming Pitfalls when Estimating Variation in Parental Investment: A Simulation Study

1. BackgroundIn many animal species, parents allocate resources to enhance offspring survival and thereby reproductive success ( parental investment). Parental care behaviors are a crucial part of parental investment, and one critical question in behavioral ecology is to which degree variation in parental care affects offspring development and survival. Crucially, parental care behaviors vary with offspring age, which creates non-trivial problems for statistical analyses, specifically when sampling is incomplete or biased. 2. MethodsWe conducted a simulation study to illustrate the problem when analyzing average parental care behaviors while not correcting for offspring age ( conventional approach), and propose a modeling approach to correct for offspring age and sampling biases. We simulated a set of different scenarios, varying with regard to sample size, sampling scheme, and variation in parental behavior. To model parent behavior as a function of offspring age, we fitted a Generalized Linear Mixed Model to each simulated data set. We included offspring age as a fixed effect and extracted Best Linear Unbiased Predictors (BLUPs) for the random intercept of parent identity. These BLUPs represent the parental behavior corrected for offspring age. Finally, we assessed how our proposed modeling approach compares to the conventional approach. 3. ResultsThe proposed modeling approach was superior to the conventional approach. More specifically, the conventional approach clearly overestimated the variation between parents, and even diagnosed appreciable variation when there was none in the simulated data. This bias was exacerbated in incomplete or unbalanced sampling schemes. 4. Conclusion.Our simulation study clearly demonstrates the necessity of correcting for offspring age in analyses of parental behavior. We strongly suggest including random slopes of offspring age within parent-offspring dyads, because doing so can reveal parent-specific trajectories of the modeled behavior against offspring age. Our approach allows for the inclusion of further categorical and continuous predictor variables that may affect parental behavior, such as parity or ecological conditions. In summary, the proposed modeling approach has several advantages over conventional methods.

animal behavior and cognition↗

bioRxiv2021

Evaluating the efficacy of a consumer-centric method for ecological sampling: Using bonobo (Pan paniscus) feeding patterns as an instrument for tropical forest characterization

O_LICharacteristics of food availability and distribution are a key component of a species ecology. Objective measurement of food resources, such as vegetation plot sampling, do not consider aspects of selection by the consumer and therefore may produce imprecise measures of availability. Further, in most animal ecology research, traditional ecological surveying often is time-intensive and supplementary to ongoing behavioral observation. We propose a method to integrate ecological sampling of an animals environment into existing behavioral data collection systems by using the consumer as the surveyor. Here, we introduce the consumer-centric method (CCM) of assessing resource availability for its ability to measure food resource abundance, distribution, and dispersion. This method catalogues feeding locations observed during behavioral observation and uses aggregated data to characterize these ecological metrics. C_LIO_LIWe evaluated the CCM relative to traditional vegetation plot surveying using accumulated feeding locations across three years visited by a tropical frugivore, the bonobo (Pan paniscus), and compared it with data derived from over 200 vegetation plots across their 50km2+ home range. C_LIO_LIWe demonstrate that food species abundance estimates derived from the CCM are comparable to those derived from traditional vegetation plot sampling after approximately 600 observation days or 60 spatially explicit feeding locations. The agreement between the methods further improved when accounting for aspects of consumer selectivity in objective vegetation plot sampling (e.g., size minima). Estimates of density from CCM correlated with plot-derived estimates and were relatively insensitive to home range inclusion and other species characteristics, but were sensitive to sampling frequency (e.g., consumption frequency). Agreement between the methods in relative distribution of resources performed better across species than expected by chance, although measures of dispersion correlated poorly. C_LIO_LIWe demonstrate that while providing a robust measure to quantify local food availability, the CCM has an advantage over traditional sampling methods as it incorporates sampling biases relevant to the consumer. Therefore, as this method can be incorporated into existing observational data collection and does not require additional ecological surveying, it serves as a promising method for behavioral ecological data collection for animal species who re-use space and consume immobile food items. C_LI

ecology↗