Cooperative breeding has long been an area of considerable fascination for research.
The very act of giving up one’s own chances at reproduction in order to help raise the young of others appears a very ‘selfless’ act, and does not fit in well with the theory of natural selection.
There can be many benefits to group-living, such as greater detection of predators, access to better quality resources (through territory defence), greater survival of young, and greater longevity of adults.
There can, however, be a number of disadvantages: individuals fight with each other over who gets access to reproduction and resources. In addition, those who do not get access to reproduction suffer the costs of having to raise someone else’s young.
This trade-off, between the costs and benefits of cooperation, and how this affects the level of conflict or concession among group members, is the core basis of our research.
We use two wild, free-living populations of cooperative birds to address these questions regarding the evolution of cooperative breeding behavior.
Both populations are fully habituated and have been worked on for many years.
The Pied Babbler Research Project, based in the Kalahari desert, was established by Dr Amanda Ridley in 2003. There are between 16-22 groups in the population annually, and groups are monitored continuously by researchers.
The Arabian Babbler Research Project, based in the Negev desert, was established by Prof Amotz Zahavi in 1974, and has been closely monitored ever since. There are 21-35 groups in the population annually (the number of groups varies between years due to group extinctions, mergers and founding events).
Both populations contain groups in which there is a single dominant pair, with all other adults helping to raise young produced by the dominant pair. Groups can be simple families (parents with retained young), or complex groups, where several males have the opportunity to mate with several females.
These complex groups are where most of the conflict (via reproductive competition) arises. Conflict in our population takes the form of eviction, physical attacks, infanticide, border conflicts, coalition dispersal and kidnapping behaviour.
We use habituation techniques to be able to get extremely detailed behavioural information to help us answer specific research questions. This allows us to walk with the group throughout the day and collect close-range recordings of their vocalisations and behaviour.
We also use habituation to be able to weigh each individual in the population on a daily basis. This give us uniquely detailed information on changes in body mass over time in relation to rearing environment, group size, reproductive events, dispersal and other significant life history events. Our approach places an emphasis on the natural behaviour of wild animals and we focus on non-invasive experimentation and manipulation.