Female monkeys use both the carrot and the stick to promote male participation in intergroup fights

Group-level cooperation often poses a social dilemma in which joint action may be difficult to achieve. Theoretical models and experimental work on humans show that social incentives, such as punishment of defectors and rewarding of cooperators, can promote cooperation in groups of unrelated individuals. Here, we demonstrate that these processes can operate in a non-human animal species, and be used to effectively promote the production of a public good. We took advantage of the fact that intergroup fights in vervet monkeys (Chlorocebus aethiops pygerythrus) are characterized by episodes of intergroup aggression with pauses in-between. During pauses, females selectively groomed males that had participated in the previous aggressive episode, but aggressed male group members that had not. In subsequent (i.e. future) episodes, males who had received either aggression or grooming participated above their personal base-line level. Therefore, female–male aggression and grooming both appear to function as social incentives that effectively promote male participation in intergroup fights. Importantly, females stood to gain much from recruiting males as the probability of winning intergroup fights was dependent on the number of active participants, relative to the number of fighters in the opposing group. Furthermore, females appear to maximize the benefits gained from recruiting males as they primarily used social incentives where and when high-quality food resources, which are the resources primarily limiting to female fitness, were at stake

In the footsteps of city foxes: evidence for a rise of urban badger populations in Switzerland

Single observations of badgers in urban areas have been interpreted as relicts of formerly rural populations that have merely survived urban encroachment. However, decades after the rise of urban fox populations in continental Europe, there is evidence from Switzerland which suggests that badgers may be following a similar trend. We present long-term traffic casualty data, a comparison over time of camera trap studies, and incidental observations collected in a Swiss citizen science project which indicate both an increase of badgers at the national scale as well as a range expansion into urban areas. Their rather delayed and slow increase, compared to foxes, might be based on slower reproduction and less flexible behavioural adaptations. Our data, however, suggest that badgers are recovering delayed from a population depression following the rabies epizootic of the 1960s and 70s and may be starting to expand their range through the colonisation of urban habitats, similar as foxes did during the 20th century

Data from: Female monkeys use both the carrot and the stick to promote male participation in intergroup fights

Group-level cooperation often poses a social dilemma in which joint action may be difficult to achieve. Theoretical models and experimental work on humans show that social incentives, such as punishment of defectors and rewarding of cooperators, can promote cooperation in groups of unrelated individuals. Here, we demonstrate that these processes can operate in a non-human animal species, and be used to effectively promote the production of a public good. We took advantage of the fact that intergroup fights in vervet monkeys (Chlorocebus aethiops pygerythrus) are characterized by episodes of intergroup aggression with pauses in-between. During pauses, females selectively groomed males that had participated in the previous aggressive episode, but aggressed male group members that had not. In subsequent (i.e. future) episodes, males who had received either aggression or grooming participated above their personal base-line level. Therefore, female–male aggression and grooming both appear to function as social incentives that effectively promote male participation in intergroup fights. Importantly, females stood to gain much from recruiting males as the probability of winning intergroup fights was dependent on the number of active participants, relative to the number of fighters in the opposing group. Furthermore, females appear to maximize the benefits gained from recruiting males as they primarily used social incentives where and when high-quality food resources, which are the resources primarily limiting to female fitness, were at stake

Arseneau-Robar_Methods_Results_ESM from Female monkeys use both the carrot and the stick to promote male participation in intergroup fights

Female monkeys use both the carrot and the stick to promote male participation in intergroup fights: Spatio-Temporal Variability in the Occurrence of Female-Male Aggression and Female-Male Groomin