Sociality in the Anthropocene

Habitat destruction, climate change and invasive species are increasingly changing the living conditions of many animals. The survival of a species depends on whether and how it can adapt its behaviour and physiology to the new conditions. The behaviour of social species is particularly complex because an individual`s behaviour depends not only on the environmental conditions of its habitat, but also on the other members of the group. The response of social animals to anthropogenic environmental change is therefore still poorly understood. Changes in habitat often lead to a shortage of food or other resources and could therefore increase conflicts between group members. At the same time, group members may support each other to compensate for poorer environmental conditions. One example are cooperative birds. In these social systems, a dominant breeding pair is supported by other group members, called helpers, in rearing the brood. A large proportion of these helpers are offspring of the breeding pair from previous years, who stay with the parents and help raise their siblings until one day they leave the parents to find their own mate. In this project, we investigate the factors that influence the decision of helpers to leave their parents. We hypothesise that the quality of the parental territory plays a crucial role, and that helpers in poorer territories disperse earlier. We also want to find out whether this is a decision of the parents, who drive away the older offspring due to conflict over reduced food resources, or a decision of the offspring, who have few opportunities in poor-quality parental territories. We will therefore study a population of cooperative breeders, the Placid Greenbul Phyllastrephus placidus, in the highly fragmented cloud forests of the Taita Hills in Kenya. We will fit the helpers with telemetry transmitters that will allow us to track the movements of helpers in the parental territory and determine when they finally leave the territory. To better understand who is driving the decision of helpers to leave the territory, we will alter the physiological status of helpers and parents to mimic conditions in territories with poor habitat quality. This project will contribute to a better understanding of how social species respond to degraded habitat conditions.