by Max Planck Society

Vulturine guineafowl occur in the savannahs of Kenya. The birds live in groups, with a strict dominance hierarchy. Credit: © Danai Papageorgiou

Many animal groups decide where to go by a process similar to voting, allowing not only alphas to decide where the group goes next but giving equal say to all group members. But, for many species that live in stable groups—such as in primates and birds—the dominant, or alpha, group members often monopolize resources, such as the richest food patches and access to mates. Scientists at the Max Planck Institute of Animal Behavior and the Cluster of Excellence Centre for the Advanced Study of Collective Behavior at the University of Konstanz have studied the links between dominance and group decision-making in wild vulturine guineafowl. They report that democratic decision-making plays an essential role in mitigating the power of alphas by deciding where to move next if those alphas are monopolizing resources.

Vulturine guineafowl are large birds native to savannahs of East Africa. They are the first bird species to have been reported to live in a multilevel society where social groups comprising from 15 to more than 60 individuals interact preferentially with other social groups. Within these large groups, there is a clear dominance hierarchy. Like in wolves and primates, the dominant, or alpha, group members can outcompete other group members and exclude them from food.

While it had long been thought that alphas lead the way and decide where the group moves next, studies over the past decade have suggested that all group members can have equal say by ‘voting’ for where the group goes next. However, it has remained to be determined whether this form of democratic decision-making exists in order to keep the power of dominants in check. “Working together as a group is critical for these birds, as their bright plumage makes isolated individuals easy targets for predators such as leopards and martial eagles,” says Damien Farine, the senior author of the study and lead research on the vulturine guineafowl project.

Despotic leadership versus democratic decision-making

The scientists found that who initiated, and therefore decided where the group moved to next, was dependent on the recent actions of the dominant group members. When groups were feeding in large spacious areas, where distributed food was equally accessible to everyone, then all group members contributed equally. However, when dominant individuals monopolized a particularly rich food patch—chasing other group members out—then the excluded subordinates combined their votes to move the group away from the patch, ultimately forcing the dominants to abandon their rich resources. These findings suggest democratic decision-making, as opposed to despotic leadership, has evolved so that all group members can obtain the resources (e.g. food and water) that they need to survive. This would not be possible if dominant individuals always decided what was best for themselves.[…]

Continue reading: Alpha animals must bow to the majority when they abuse their power