Roger Mundry

Knowing where to find what kind of food, and when, is essential for survival and reproduction. Studying animals’ foraging strategies thus provides insights into the cognitive processes underlying real-world problem solving. 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 ). An exceptional wildfire that destroyed most ripe fruits in 2019 provided a quasi-experimental opportunity to assess whether Guinea baboons flexibly adjusted their space use to an unexpected change in resource availability or instead continued to follow habitual routines. 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, when Natal oranges were available again, the baboons 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 ca. 40 min earlier toward the target area when S. spinosa was in season than when it was not. In conclusion, Guinea baboons rapidly adjusted their space use patterns in response to changes in the availability of a high-value food resource. These results underscore their capacity for flexible, reward-sensitive decision-making and goal-directed foraging.

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.

Objectives: In human foraging societies, hunting skill is often interpreted as a signal of male quality linked to reproductive success through his ability to provision his family and community. Similarly, in some bird and insect species, males offer mates food to indicate their quality as a provider. Among nonhuman primates, however, the relationship between meat sharing and reproductive success is underexplored, leaving the evolutionary origins of this phenomenon unresolved. Materials and Methods: 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 transfer prey, and respond to male foraging skill. We combined records of 109 meat‐eating events with 9 years of behavioral data to test whether males who more frequently acquired and transferred meat to females had more females in their social units for longer. Results: Contrary to our predictions, we found no evidence that females preferred males who acquired or transferred meat more frequently, suggesting that meat acquisition is not a signal of male quality in Guinea baboons. Discussion: 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 besides her unit male, including the first documented cases of female prey capture (11% of events) in this species. Thus, females likely apply other, more pertinent criteria in mate choice.

Body size is a fundamental feature of an organism’s biology, and studies of body size growth can yield insights into factors that shape evolutionary change within and between species. However, apart from humans, variability in body size growth within primate species across environments remains poorly known. We used non-invasive parallel-laser photogrammetry to compare body size growth of two ecologically distinct populations of mountain gorillas, from Bwindi Impenetrable National Park, Uganda and Volcanoes National Park, Rwanda, in the Virunga Massif (n = 197, aged 0.3–42.7 years). Bwindi females attained a smaller adult size than Virunga females, despite continuing their growth over a longer duration. Population differences in male adult size were minimal, although Bwindi males continued growth in back breadth over a longer duration. For both sexes, Bwindi gorillas were smaller than Virunga gorillas as young infants, and these size differences decreased over ontogeny. This study provides the first evidence of within-species variation in body size growth among living wild apes between populations that exhibit ecological and life-history differences. This variation could be due to genetic variation, phenotypic plasticity, reproductive trade-offs and/or ecological constraints and have implications for understanding body size growth variation in humans and other species.

Maternal care is ubiquitous in mammals, yet its degree and duration vary across taxa. In primates, mothers provide extended care for young and follow similar developmental transitions in the mother–infant relationship, yet at different paces of change. Since ecological pressures shape life‐history traits including female reproductive rate and timing of infant independence, research is needed on mother–infant relationships in wild populations exposed to energetic constraints and predation risk. Assamese macaques ( Macaca assamensis ) of the study population are seasonal breeders living in an unpredictable environment, where fluctuating food availability imposes energetic challenges on mothers and infants. We quantitatively describe how maternal care and offspring independence develop throughout infancy. Using continuous focal observations on 59 infants, we model the nonlinear age‐trajectories of mother–infant proximity and transitions from dependent to independent feeding and locomotion, and estimated sex differences in these trajectories. Newborns were fully dependent on their mothers for feeding and transport, with mothers maintaining close proximity. A transitional phase emerged between 1 and 3 months of age, marked by reduced maternal proximity and increasing infant independence. During the second half of infancy, infants achieved near‐complete locomotor and feeding independence, while residual proximity and body contact persisted. No sex differences were detected in the mother–infant relationship trajectory. Collectively, the timing of maternal investment aligns with the breeding strategy of this seasonal species, with females balancing investment in current and future reproduction. This study establishes a baseline for examining how ecological variability affects the timing and pace of mother–infant behavioral transitions.

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.

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.