Bystanders, parcelling, and an absence of trust in the grooming interactions of wild male chimpanzees

The evolution of cooperation remains a central issue in socio-biology with the fundamental problem of how individuals minimize the risks of being short-changed (‘cheated’) should their behavioural investment in another not be returned. Economic decisions that individuals make during interactions may depend upon the presence of potential partners nearby, which o ers co operators a temptation to defect from the current partner. The parcelling model posits that donors subdivide services into parcels to force cooperation, and that this is contingent on opportunities for defection; that is, the presence of bystanders. Here we test this model and the e ect of bystander presence using grooming interactions of wild chimpanzees. We found that with more bystanders, initiators gave less grooming at the beginning of the bout and were more likely to abandon a grooming bout, while bouts were less likely to be reciprocated. We also found that the groomer’s initial investment was not higher among frequent groomers or stronger reciprocators, suggesting that contrary to current assumptions, grooming decisions are not based on trust, or bonds, within dyads. Our work highlights the importance of considering immediate social context and the in uence of bystanders for understanding the evolution of the behavioural strategies that produce cooperation

First report of food sharing among Nicobar long-tailed macaques

This is an accepted manuscript of an article published by Elsevier in Quaternary International on 04/12/2020, available online: https://doi.org/10.1016/j.quaint.2020.11.049 The accepted version of the publication may differ from the final published version.The sharing of food is an essential component of human societies and has likely played a key role for the evolution of several human traits such as reduced sexual dimorphism, a more flexible maturational pace in relation to environmental variation and an increase in human tolerance and co-operation. For this reason, the investigation of the evolutionary origins of food sharing in humans has been a central topic in biological anthropology. Since behavior does not fossilize, investigations on food sharing in non-human primates are key in providing a window into the evolution of food sharing and co-operation in humans. Among non-human primates, evidence of non-kin food sharing has largely been found in apes and New World monkeys, while this phenomenon has rarely been reported in Old World monkeys. Here we provide the first descriptive report of food sharing in wild macaques. We studied two free-ranging groups of Nicobar long-tailed macaques from two different islands (i.e., Great Nicobar and Katchal), that have very different ecological settings and vegetation, for over 168 days. Using focal animal sampling, we observed a total of 18 food sharing events, that revolved around monopolizable food items (coconut and termite log) and mostly involved males. Females, even when present near the food owner, took very little interest in observing the event. The macaques shared food only among the individuals who sat close to the food owner, who, in turn, displayed very little aggression against bystanders. Given that, among Nicobar macaques, males have been previously described as forming strong social relationships, and since harassment was rarely observed in the present study, we argue that our observations could support the reciprocal exchange rather than the harassment hypothesis. While more observations are needed to better clarify the ultimate function of food sharing in this species, our study on Nicobar long-tailed macaques highlights some features that might make this species an ideal model to study the evolution of human behavior

Anogenital scent-marking signals fertility in a captive female Alaotran gentle lemur

The Lake Alaotra gentle lemur (Hapalemur alaotrensis) is one of the 25 most endangered primates in the world and shows low success rate in captive breeding programmes. It is therefore vital to further understand its reproductive biology. We studied a captive troop consisting of five individuals hosted at Jersey Zoo during breeding and non-breeding periods over 1 year. We collected behavioural data (n = 318 h) using all occurrence of some behaviours and ad libitum sampling methods, as well as faecal (n = 54) and anogenital scent (n = 35) samples of the breeding female. We measured sex hormone levels using enzyme immunoassay technique and investigated the volatile component of odour signals using solid-phase microextraction and gas chromatography-mass spectrometry. We observed sexual and aggressive behaviours occasionally during the breeding period. Our regression analysis showed that only period significantly predicted rates of female anogenital scent-marking, whereby the female performed anogenital scent-marking more frequently during the breeding rather than the non-breeding period. In contrast, female hormone levels did not significantly explain variation in rates of neither male nor female olfactory, sexual and affiliative behaviours, suggesting that individuals' behaviour alone is not an effective indicator of the ovulation window. The volatile chemical profile of anogenital odour secretions changed over the study, with four compounds distinguishing the fertile window during the breeding period. In conclusion, our findings suggest that anogenital scent-marking may signal the reproductive status of captive female gentle lemurs

Dominance rank predicts social network position across developmental stages in rhesus monkeys

Social network analysis is increasingly common in studying the complex interactions among individuals. Across a range of primates, high-ranking adults are generally more socially connected, which results in better fitness outcomes. However, it still remains unclear whether this relationship between social network position and dominance rank emergences in infancy and whether, in species with a social transmission of dominance rank, social network positions are driven by the presence of the mother. To fill this gap, we first explored whether dominance ranks were related to social network position, measured via eigenvector centrality, in infants, juveniles, and adults in a troop of semi-free ranging rhesus macaques (Macaca mulatta). We then examined relationships between dominance rank and eigenvector centrality in a peer-only group of yearlings who were reared with their mothers in either a rich, socially complex environment of multigenerational (MG) kin support or a unigenerational (UG) group of mothers and their infants from birth through eight months. In experiment 1, we found that mother’s network position predicted offspring network position, and that dominants across all age categories were more central in affiliative networks (social contact, social grooming, and social play). Experiment 2 showed that high-ranking yearlings in a peer-only group were more central only in the social contact network. Moreover, yearlings reared in a socially complex environment of MG kin support were more central. Our findings suggest that the relationship between dominance rank and social network position begins early in life, and that complex early social environments can promote later social competency. Our data add to the growing body of evidence that the presence/absence of the mother and kin influence how dominance rank affects social network position. These findings have important implications for the role of caregivers in the social status of developing primates, which ultimately ties to health and fitness outcomes

Behavioral and hormonal changes following social instability in young rhesus macaques (Macaca mulatta)

This is an accepted manuscript of an article published by American Psychological Association in Journal of Comparative Psychology, available online at: https://doi.org/10.1037/com0000297 This article may not exactly replicate the authoritative document published in the APA journal. It is not the copy of recordSocial instability (SI) occurs when there is competition over social status. Reduced certainty of social status can lead to heightened aggression, which can increase physiological stress responses, as individuals prepare to fight for their social status. However, adults can take proactive coping mechanisms to reduce the physiological stress induced by SI, such as increasing affiliation. Very little is known, however, about the behavioral and hormonal effects of SI early in development. Filling these gaps in knowledge would add to the fields of primatology and developmental and comparative psychology. We conducted an opportunistic study of a peer group of 18 rhesus macaque (Macaca mulatta) yearlings before and during SI. We used social network analysis to measure individuals’ dominance certainty (DC, in their aggressive and submissive network) and their position in affiliative networks (grooming and play) and analyzed hair cortisol concentrations (HCCs). As predicted, during SI, we observed a decrease in DC, indicating that individuals had less stable dominance positions. As well, during SI, we observed increased rates of social grooming and decreased rates of social play, reflecting potential coping mechanisms. More socially connected individuals in social grooming and social play networks received higher levels of coalitionary support. Contrary to predictions, DC did not predict HCCs; rather individuals that were more connected in the social play network exhibited smaller increases in HCCs during SI, revealing a potential buffering effect of social play. Our results underscore the need for further research on the effects of SI during ontogeny.Division of Intramural Research at the Eunice Kennedy Shriver National Institute of Child Health and Human Development

Olfactory signals and fertility in zoo-housed Alaotran lemurs

Paper presented at The 3rd Faculty of Science and Engineering Festival of Research, University of Wolverhampton, 26th-27th May, 2022.This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie grant agreement No. 890341 to S.F. and S.V

Anogenital scent-marking signals fertility in a captive female Alaotran gentle lemur

The Lake Alaotra gentle lemur (Hapalemur alaotrensis) is one of the 25 most endangered primates in the world and shows low success rate in captive breeding programmes. It is therefore vital to further understand its reproductive biology. We studied a captive troop consisting of five individuals hosted at Jersey Zoo during breeding and non-breeding periods over 1 year. We collected behavioural data (n = 318 h) using all occurrence of some behaviours and ad libitum sampling methods, as well as faecal (n = 54) and anogenital scent (n = 35) samples of the breeding female. We measured sex hormone levels using enzyme immunoassay technique and investigated the volatile component of odour signals using solid-phase microextraction and gas chromatography-mass spectrometry. We observed sexual and aggressive behaviours occasionally during the breeding period. Our regression analysis showed that only period significantly predicted rates of female anogenital scent-marking, whereby the female performed anogenital scent-marking more frequently during the breeding rather than the non-breeding period. In contrast, female hormone levels did not significantly explain variation in rates of neither male nor female olfactory, sexual and affiliative behaviours, suggesting that individuals' behaviour alone is not an effective indicator of the ovulation window. The volatile chemical profile of anogenital odour secretions changed over the study, with four compounds distinguishing the fertile window during the breeding period. In conclusion, our findings suggest that anogenital scent-marking may signal the reproductive status of captive female gentle lemurs

Advanced survey effort required to obtain bat assemblage data in temperate woodlands (Chiroptera)

There is a lack of precise guidelines concerning the survey effort required for advanced bat surveys in temperate European woodlands, resulting in a lack of standardisation in survey methods. In this study we assess catch data from 56 bat trapping surveys at 11 UK woodland sites in order to provide recommendations for mist net survey effort required to gain meaningful bat assemblage data in temperate woodlands. Species accumulation curves were produced and were used to develop two novel values for survey effort: the minimum survey threshold (MST), whereby surveyors are more likely than not to encounter less dominant species; and the known species threshold (KST), the point where a given percentage (in our case, 75%) of the known species assemblage for a site is likely to be reached and beyond which there are diminishing returns for survey effort. For our data, the mean of MST was 17.4 net hours, and for KST, the mean was 29.8 net hours. The MST and KST values were reached during the second and third surveys, respectively. These proposed values are adaptable based on location and known species assemblage and may be used for planning advanced bat surveys in temperate woodlands not only to maximise survey efficacy and use of limited resources but to ensure ethical viability of undertaking advanced surveys in the first place.Published onlin

Addressing the challenges of research on human-wildlife interactions using the concept of coupled natural & human systems

© 2021 The Authors. Published by Elsevier. This is an open access article available under a Creative Commons licence. The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1016/j.biocon.2021.109095With the global expansion of human populations, research on human-wildlife interactions (HWIs) has become increasingly important in conservation science. Despite its growing importance, such research faces challenges that include a bias towards evaluating wildlife- compared to human-related aspects of interactions, limited focus on the complexity of HWIs and their effects, assessments of more observable compared to hidden/subtle effects, and the lack of comparative studies. Here we review how the Coupled Natural and Human Systems (CNHS) approach has been useful to address these challenges. We demonstrate the relative dearth in studies that have implemented CNHS approaches in the context of HWIs, compared to human interactions with biophysical, abiotic, and other biotic natural systems. We next review conceptual CNHS frameworks implemented to model HWIs, their structural and functional similarities and differences, and reveal how they help to address some, but not all, of the afore-mentioned challenges. We then construct a general, integrated conceptual framework for human-wildlife CNHS borrowing elements from pre-existing frameworks, which includes a standardized designation/nomenclature of CNHS components and their relationships and builds on pre-existing frameworks by placing a greater emphasis on less visible outcomes of HWIs that remain under-represented in the CNHS literature. We discuss the potential and scope of this integrated framework in terms of its usefulness to address the above challenges, and the importance of moving human-wildlife CNHS frameworks from merely providing conceptual platforms towards their analytical utility as single ‘whole’ systems