A new study has demonstrated that it is not just mammals that have complex societies. The results of a new observational study reveal that birds–more specifically vulture guinea fowl that live in Africa–can keep track of relationships with hundreds of others. The results challenge the prevailing view that big brains are a requirement for complex society. What’s more, these birds have learned the art of finesse–they not only behave “highly cohesively”, but unlike many humans, they don’t display any aggression between groups.
Researchers tracked the social relationships in a population of more than 400 adult birds in Kenya for 12 months. The researchers individually tagged all birds in the population. By observing them they discovered that the population comprised 18 distinct social groups, with 13 to 65 birds in each group. The researchers witnessed the birds walking very long distances together — up to 15 kilometers a day — remaining within a few meters of everyone else and when conditions were very dry, all the groups in a roost sometimes walked a kilometer to the nearest river together to drink.
Complex societies occur when individuals repeatedly interact with the same individuals across a range of different contexts, and have different types of relationships with different individuals. These usually require animals to live in quite large and quite stable social groups. Because this requires the animals to keep track of individuals in both their own and other groups, the assumption has long been that multilevel societies should only exist in species with the intelligence to cope with this complexity.
While many bird species live in groups, these are either open, lacking long-term stability, or highly territorial, lacking associations with other groups. However, the groups of guinea fowl associated with each other based on preference, rather than random encounters, and these groups remained stable over time.
Groups of vulturine guinea fowl can become very large, and when multiple groups come into contact the number of birds moving together can reach into the hundreds. However, when these ‘super-groups’ eventually split, they do so back into their original stable group units, meaning that individuals are knowledgeable about who is part of their group and who is not.