Mothers play a crucial role in the early development and survival of mammalian offspring, and differences in maternal care may differentially affect offspring’s 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 offspring’s 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.

Microsatellite data for the manuscript "Gene flow and vertical stratification of pollination in the bat-pollinated liana species Marcgravia longifolia"

Microsatellite data for the manuscript "Gene flow and vertical stratification of pollination in the bat-pollinated liana species Marcgravia longifolia"

Music and rhythm are typical features of all human cultures, but their biological origins remain unclear. Recent investigations suggest that rhythmic features of human music are shared with animal vocalizations. Moreover, emotions influence human speech and music, similar to what arousal does to the structure of animal sounds. We investigated Coppery titi monkeys' (Plecturocebus cupreus) duet rhythms to assess adherence to rhythmic patterns previously observed only in Old World primates and to deepen our understanding of the proximate causes of non-human primate song rhythm. Titis’ songs were remarkably isochronous, but their tempo depended on the social context: songs sung during territorial confrontations have a slower pace than during early morning singing. Songs had a faster tempo and were less regular when infants were present, suggesting a speed-accuracy tradeoff. Finally, we found that pair-mates perform isochronous songs with the same precision, suggesting that isochrony plays a role in boosting pair coordination, as it does in other singing primates. Our investigation shed light on the ultimate and proximate causes of primates' isochronous rhythm, confirming its presence for the first time in a New World monkey and highlighting the role of social factors in shaping its timing and regularity in the short term.

This manuscript describes a failed experiment on cooperation with wild Guinea baboons. There is no dataset associated with this manuscript. However, materials relating to the design, construction, and operation of the boxes used in this experiment can be found at the following GitHub organization https://github.com/CooperationboxExp, and its repositories: Hardware DOI:10.5281/zenodo.14178666, Firmware DOI:10.5281/zenodo.14178677. In addition, links to a YouTube playlist of video exemplars are available in the repository. All researchers who appear in the accompanying videos gave their informed consent with regard to the video’s distribution.

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