Sociable weavers are highly cooperative birds that work together to accomplish diverse tasks, from building their highly distinctive communal nests to help raising the chicks of others or defending the colony from predators. Their multi-level society and different types of cooperative behaviours make them an ideal study model to investigate the benefits and costs of sociality and the evolutionary mechanisms that allow cooperation to evolve and be maintained.
Currently, much of our research addresses the following themes:
1. The role of partner choice in the evolution and of cooperation.
Theoretical models show that if more cooperative individuals are preferred as sexual or social partners, cooperation is more advantageous than cheating or defecting, and studies in humans have shown a preference for associating with more cooperative individuals. However, field tests of these mechanisms have been difficult to conduct and the results are mixed. We are using micro-tracking, social networks analyses and long-term data to examine social and sexual partner choice in this species and its potential role for the evolution of cooperation. This project is funded by the European Research Council (ERC, Consolidator grant to R. Covas) and the French National Research Agency (ANR, AAPG2019 to C. Doutrelant).
2.Does sociality mitigate the role of adverse conditions?
Sociality and, in particular, cooperative breeding are thought to buffer against the effects of adverse climatic conditions. This could be particularly important given that the frequency and intensity of extreme weather events such as droughts and heat waves, is predicted to increase under the current climate change scenario. We use our long-term data to establish whether sociality may lessen the impacts of these adverse conditions at the individual and population level.
3. Maternal investment and concealed helper effects
In egg-laying species, females’ investment in reproduction starts with the formation of the egg, and is expected to be influenced by the different factors that affect female condition and reproductive success. In cooperative breeders, helpers might also influence reproductive success and we investigate whether and how the presence of helpers interacts with environmental conditions to shape female reproductive investment. In addition, we are interested in understanding how these pre-natal effects influence the life-history trajectories and fitness of offspring.
4. Conflict and infanticide
In all cooperative societies there is also conflict and even extreme asocial behaviours, such as infanticide. We use detailed behavioural observations and our long-term data to understand which factors influence the balance between cooperation and conflict in our system.