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Hartman CRA, Wilkinson GS, Razik I, Hamilton IM, Hobson EA, Carter GG. Hierarchically embedded scales of movement shape the social networks of vampire bats. Proc Biol Sci 2024; 291:20232880. [PMID: 38654645 PMCID: PMC11040254 DOI: 10.1098/rspb.2023.2880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Accepted: 03/25/2024] [Indexed: 04/26/2024] Open
Abstract
Social structure can emerge from hierarchically embedded scales of movement, where movement at one scale is constrained within a larger scale (e.g. among branches, trees, forests). In most studies of animal social networks, some scales of movement are not observed, and the relative importance of the observed scales of movement is unclear. Here, we asked: how does individual variation in movement, at multiple nested spatial scales, influence each individual's social connectedness? Using existing data from common vampire bats (Desmodus rotundus), we created an agent-based model of how three nested scales of movement-among roosts, clusters and grooming partners-each influence a bat's grooming network centrality. In each of 10 simulations, virtual bats lacking social and spatial preferences moved at each scale at empirically derived rates that were either fixed or individually variable and either independent or correlated across scales. We found that numbers of partners groomed per bat were driven more by within-roost movements than by roost switching, highlighting that co-roosting networks do not fully capture bat social structure. Simulations revealed how individual variation in movement at nested spatial scales can cause false discovery and misidentification of preferred social relationships. Our model provides several insights into how nonsocial factors shape social networks.
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Affiliation(s)
- C. Raven A. Hartman
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA
| | | | - Imran Razik
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA
- Smithsonian Tropical Research Institute, Balboa, Ancón, Apartado Postal 0843-03092, Panama
| | - Ian M. Hamilton
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA
- Department of Mathematics, The Ohio State University, Columbus, OH 43210, USA
| | - Elizabeth A. Hobson
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Gerald G. Carter
- Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH 43210, USA
- Smithsonian Tropical Research Institute, Balboa, Ancón, Apartado Postal 0843-03092, Panama
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Debetencourt B, Barry MM, Arandjelovic M, Stephens C, Maldonado N, Boesch C. Camera traps unveil demography, social structure, and home range of six unhabituated Western chimpanzee groups in the Moyen Bafing National Park, Guinea. Am J Primatol 2024; 86:e23578. [PMID: 37985945 DOI: 10.1002/ajp.23578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 11/02/2023] [Accepted: 11/05/2023] [Indexed: 11/22/2023]
Abstract
Precise estimates of population dynamics and social grouping patterns are required for effective conservation of wild animal populations. It is difficult to obtain such information on non-human great apes as they have slow reproductive rates. To gain a better understanding of demography in these populations, previous research has typically involved habituation\, a process that requires years. Here, we collected data continuously over year-long periods to monitor an unhabituated population of critically endangered Western chimpanzees (Pan troglodytes verus) in the Moyen Bafing National Park, Guinea. We used two arrays of 100 camera traps that were placed opportunistically in two distinct 100 km2 sites, named Bakoun and Koukoutamba. We identified 227 individuals in Bakoun and 207 in Koukoutamba through their unique facial features. Our camera trap data make clear that these individuals belong to six and seven closed groups, respectively. Six of those groups were near-completely sampled with an average minimum size of 46.8 individuals (range: 37-58), and a mean adult sex ratio of 1.32 (range: 0.93-2.10). We described the demographic composition of these groups and use Bayesian social network analysis to understand population structure. The network analyses suggested that the social bonds within the two populations were structured by sex homophily, with male chimpanzees being more or equally likely to be observed together than other adult associations. Through estimation of minimum convex polygons, we described the minimum home range for those groups. Compared to other chimpanzee groups living in a similar environment (mosaic savanna-forest), the Moyen Bafing region seems to host a high-density of chimpanzees with small home ranges for their group size. Our research highlights the potential of camera traps for studying the demographic composition of chimpanzee populations with high resolution and obtaining crucial information on several groups in a time-efficient and cost-effective way.
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Affiliation(s)
- Benjamin Debetencourt
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology (MPI-EVA), Leipzig, Germany
- Wild Chimpanzee Foundation, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Mamadou Moussa Barry
- Wild Chimpanzee Foundation, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Mimi Arandjelovic
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology (MPI-EVA), Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv), Leipzig, Germany
| | - Colleen Stephens
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology (MPI-EVA), Leipzig, Germany
| | - Nuria Maldonado
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology (MPI-EVA), Leipzig, Germany
| | - Christophe Boesch
- Department of Primate Behavior and Evolution, Max Planck Institute for Evolutionary Anthropology (MPI-EVA), Leipzig, Germany
- Wild Chimpanzee Foundation, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Jang H, Ross CT, Boyette AH, Janmaat KR, Kandza V, Redhead D. Women's subsistence networks scaffold cultural transmission among BaYaka foragers in the Congo Basin. SCIENCE ADVANCES 2024; 10:eadj2543. [PMID: 38198536 PMCID: PMC10780863 DOI: 10.1126/sciadv.adj2543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 12/11/2023] [Indexed: 01/12/2024]
Abstract
In hunter-gatherer societies, women's subsistence activities are crucial for food provisioning and children's social learning but are understudied relative to men's activities. To understand the structure of women's foraging networks, we present 230 days of focal-follow data in a BaYaka community. To analyze these data, we develop a stochastic blockmodel for repeat observations with uneven sampling. We find that women's subsistence networks are characterized by cooperation between kin, gender homophily, and mixed age-group composition. During early childhood, individuals preferentially coforage with adult kin, but those in middle childhood and adolescence are likely to coforage with nonkin peers, providing opportunities for horizontal learning. By quantifying the probability of coforaging ties across age classes and relatedness levels, our findings provide insights into the scope for social learning during women's subsistence activities in a real-world foraging population and provide ground-truth values for key parameters used in formal models of cumulative culture.
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Affiliation(s)
- Haneul Jang
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
- Institute for Advanced Study in Toulouse, Toulouse School of Economics, 1 Esplanade de l'Université, 31080 Toulouse cedex 06, France
| | - Cody T. Ross
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Adam H. Boyette
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Karline R.L. Janmaat
- Department of Evolutionary and Population Biology, Faculty of Science, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
- Department of Cognitive Psychology, Faculty of Social and Behavioural Sciences, Leiden University, Wassenaarseweg 52, 2333 AK, Leiden, Netherlands
| | - Vidrige Kandza
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Daniel Redhead
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
- Department of Sociology, University of Groningen, Grote Rozenstraat 31, 9712 TG Groningen, Netherlands
- Inter-University Center for Social Science Theory and Methodology, University of Groningen, Groningen, Netherlands
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