Brendan J. Barrett’s research while affiliated with University of Konstanz and other places

Recent proliferation of GPS technology has transformed animal movement research. Yet, time‐series data from this recent technology rarely span beyond a decade, constraining longitudinal research. Long‐term field sites hold valuable historic animal location records, including hand‐drawn maps and semantic descriptions. Here, we introduce a generalised workflow for converting such records into reliable location data to estimate home ranges, using 30 years of sleep‐site data from 11 white‐faced capuchin (Cebus imitator) groups in Costa Rica. Our findings illustrate that historic sleep locations can reliably recover home range size and geometry. We showcase the opportunity our approach presents to resolve open questions that can only be addressed with very long‐term data, examining how home ranges are affected by climate cycles and demographic change. We urge researchers to translate historical records into usable movement data before this knowledge is lost; it is essential to understanding how animals are responding to our changing world.

Tool‐using primates often show sex differences in both the frequency and efficiency of tool use. In species with sex‐biased dispersal, such within‐group variation likely shapes patterns of cultural transmission of tool‐use traditions between groups. On the Panamanian islands of Jicarón and Coiba, a population of white‐faced capuchins ( Cebus capucinus imitator )—some of which engage in habitual stone tool use—provide an opportunity to test hypotheses about why such sex‐biases arise. On Jicarón, we have only observed males engaging in stone tool use, whereas on Coiba, both sexes are known to use tools. Using 5 years of camera trap data, we provide evidence that this variation likely reflects a sex difference in tool use rather than a sampling artifact, and then test hypotheses about the factors driving this pattern. Differences in physical ability or risk‐aversion, and competition over access to anvils do not account for the sex‐differences in tool‐use we observe. Our data show that adult females are physically capable of stone tool use: adult females on Coiba and juveniles on Jicarón smaller than adult females regularly engage in tool use. Females also have ample opportunity to use tools: the sexes are equally terrestrial, and competition over anvils is low. Finally, females rarely scrounge on left‐over food items either during or after tool‐using events, suggesting they are not being provisioned by males. Although it remains unclear why adult white‐faced capuchin females on Jicarón do not use stone‐tools, our results illustrate that such sex biases in socially learned behaviors can arise even in the absence of obvious physical, environmental, and social constraints. This suggests that a much more nuanced understanding of the differences in social structure, diet, and dispersal patterns are needed to explain why sex‐biases in tool use arise in some populations but not in others.

Understanding the amount of space required by animals to fulfill their biological needs is essential for comprehending their behavior, their ecological role within their community, and for effective conservation planning and resource management. The space-use patterns of habituated primates often are studied by using handheld GPS devices, which provide detailed movement information that can link patterns of ranging and space-use to the behavioral decisions that generate these patterns. However, these data may not accurately represent an animal’s total movements, posing challenges when the desired inference is at the home range scale. To address this problem, we used a 13-year dataset from 11 groups of white-faced capuchins (Cebus capucinus imitator) to examine the impact of sampling elements, such as sample size, regularity, and temporal coverage, on home range estimation accuracy. We found that accurate home range estimation is feasible with relatively small absolute sample sizes and irregular sampling, as long as the data are collected over extended time periods. Also, concentrated sampling can lead to bias and overconfidence due to uncaptured variations in space use and underlying movement behaviors. Sampling protocols relying on handheld GPS for home range estimation are improved by maximizing independent location data distributed across time periods much longer than the target species’ home range crossing timescale.

Terrestrial mammals exploiting coastal resources must cope with the challenge that resource availability and accessibility fluctuate with tidal cycles. Tool use can improve foraging efficiency and provide access to structurally protected resources that are otherwise unavailable (e.g. molluscs and fruits). To understand how variable accessibility of valuable resources shapes behavioural patterns, and whether tool use aids in the efficient exploitation of intertidal resources, we compared the relationship between tidal cycles and activity patterns of tool-using versus non-tool-using groups of white-faced capuchin monkeys on Jicarón Island in Coiba National Park, Panama. Although tool use on Jicarón is localized to a small stretch of coast (approx. 1 km), all coastal groups forage on intertidal resources. Using more than 5 years of camera trap data at varying distances from the coast, we found that capuchins on Jicarón showed increased coastal activity during specific parts of the tidal cycle, and that this relationship differed between tool-using and non-tool-using groups, as well as between seasons. Activity patterns of tool-using capuchins were more strongly and consistently tied to tidal cycles compared with non-tool-users, indicating that tool use might allow for more efficient exploitation of tidal resources. Our findings highlight the potential of tool use to aid niche expansion.

Tool-using primates often show sex differences in both the frequency and efficiency of tool use. In species with sex-biased dispersal, such within-group variation likely shapes patterns of cultural transmission of tool-use traditions between groups. On the Panamanian islands of Jicarón and Coiba, a population of white-faced capuchins ( Cebus capucinus imitator ) — some of which engage in habitual stone tool use — provide an opportunity to test hypotheses about why such sex-biases arise. On Jicarón, we have only observed males engaging in stone tool use, whereas on Coiba, both sexes are known to use tools. Using 5 years of camera trap data, we show that this variation reflects a true sex difference in tool use rather than a sampling artefact, and then test hypotheses about the factors driving this pattern. Differences in physical ability or risk-aversion, and competition over access to anvils do not account for the sex-differences in tool-use we observe. Our data show that females are physically capable of stone tool use: females on Coiba and juveniles on Jicarón as small and smaller than adult females regularly engage in tool use. Females also have ample opportunity to use tools: the sexes are equally terrestrial, and competition over anvils is low. Finally, females rarely scrounge on left-over food items either during or after tool-using events, suggesting they are not being provisioned by males. Although it remains unclear why white-faced capuchin females on Jicarón do not use stone-tools, our results illustrate that such sex biases in socially learned behaviors can arise even in the absence of obvious physical, environmental and social constraints. This suggests that a much more nuanced understanding of the differences in social structure, diet and dispersal patterns are needed to explain why sex-biases in tool use arise in some populations but not in others.

Terrestrial mammals exploiting coastal resources must cope with the challenge that resource availability and accessibility fluctuate with tidal cycles. Tool use can improve foraging efficiency and provide access to structurally protected resources that are otherwise unavailable (e.g., mollusks and fruits). To understand how variable accessibility of valuable resources shapes behavioral patterns, and whether tool use aids in the efficient exploitation of intertidal resources, we compared the relationship between tidal cycles and activity patterns of tool-using vs. non-tool-using groups of white-faced capuchin monkeys on Jicarón Island in Coiba National Park, Panama. Although only a single group of capuchins on Jicarón uses tools, all coastal groups forage on intertidal resources. Using data from >3 years of camera trapping at varying distances from the coast, we found that capuchins on Jicarón showed increased coastal activity during specific parts of the tidal cycle, and that this relationship differed between tool-using and non-tool-using groups, as well as between seasons. Activity patterns of tool-using capuchins were more strongly and consistently tied to tidal cycles compared to non-tool-users, indicating that tool use might allow for more efficient exploitation of tidal resources. Our findings highlight the potential of tool use to aid niche expansion.

Two‐option choice experimental designs are the most commonly employed framework for identifying evidence of social learning or social learning strategies in captive and wild populations. In nature, however, animals often choose from more than two behaviours, and multiple innovations may arise simultaneously. Studies of animal social learning are often constrained by small sample sizes, which limit researchers' ability to convincingly identify the proposed social learning strategy responsible for behavioural choice. In this study, I examine whether expanding behavioural options from k = 2 to k > 2 and increasing sample size affects inferential power in identifying social learning strategies. I focus on three frequency‐dependent learning strategies: conformist transmission, unbiased transmission and anti‐conformist transmission. I simulate 100 datasets for 72 parameter combinations, yielding 7200 simulations. I evaluate number of options (k = 2, 3, 4, 5), population size (n = 5, 10, 25, 50, 100, 250) and the logarithmic strength of frequency dependence (log(f) = log(1∕3), log(1), log(3)). I then fit a Bayesian social learning model to simulated data to evaluate the percent of the posterior consistent with type of frequency dependence, posterior standard deviations, highest posterior density intervals and posterior medians relative to the true simulated value of log(f). I show that increasing the number of options an animal can choose from increases the accuracy and certainty of identifying the type and magnitude of frequency‐dependent social learning. These effects are particularly pronounced at small to intermediate sample sizes, which are common in empirical studies of animal social learning. These findings suggest that knowing what an animal did not choose is equally important as knowing what an animal did choose when identifying social learning strategies. By strategically increasing the number of behaviours from which an animal can choose, researchers can increase inferential power in identifying social learning strategies without increasing sample size, that is, adding additional animals or collecting more data.

Culture is an outcome of both the acquisition of knowledge about behaviour through social transmission, and its subsequent production by individuals. Acquisition and production are often discussed or modelled interchangeably, yet to date no study has explored the consequences of their interaction for cultural diffusions. We present a generative model that integrates the two, and ask how variation in production rules might influence diffusion dynamics. Agents make behavioural choices that change as they learn from their productions. Their repertoires may also change, and the acquisition of behaviour is conditioned on its frequency. We analyse the diffusion of a novel behaviour through social networks, yielding generalizable predictions of how individual-level behavioural production rules influence population-level diffusion dynamics. We then investigate how linking acquisition and production might affect the performance of two commonly used inferential models for social learning; network-based diffusion analysis, and experience-weighted attraction models. We find that the influence that production rules have on diffusion dynamics has consequences for how inferential methods are applied to empirical data. Our model illuminates the differences between social learning and social influence, demonstrates the overlooked role of reinforcement learning in cultural diffusions, and allows for clearer discussions about social learning strategies.

Culture is an outcome of the acquisition of knowledge about behaviour through social transmission, and its subsequent production. Transmission and production are often discussed interchangeably or modeled separately, yet to date, no study has accounted for both processes and explored their interaction. We present a generative model that integrates the two in order to explore how variation in either might shape cultural diffusion dynamics. Agents make behavioural choices that change as they learn from their behavioural productions. Their repertoires also change over time, and the social transmission of behaviours depends on their frequency. We diffuse a novel behaviour through social networks across a large parameter space to demonstrate how accounting for both transmission and production reveals dependencies between individual-level behavioural production rules and population-level diffusion dynamics. We then investigate how such dependencies might affect the performance of two commonly used inferential models for social learning; Network-based Diffusion Analysis (NBDA), and Experienced Weighted Attraction models (EWA). By clarifying the distinction between acquisition and usage, we illuminate often-overlooked theoretical differences between social learning and social influence. These distinctions yield consequences and new considerations for how inferential methods are applied to empirical studies of culture.