Co-operation, conflict and the coordination of care in a social bird

Parents often cooperate to care for offspring, but sexual conflict over the amount of care that each provides is inevitable because the selfish interests of parents differ. The resulting 'investment game' between males and females has been explored extensively in species with biparental care, but this game becomes far more complex in cooperative breeding systems where parents are assisted by helpers in caring for young. Investment games in such systems have a highly variable outcome in terms of the relative amounts of care provided by parents and helpers (Green et al. 2016). Most importantly, the mechanism through which carers negotiate the optimal investment of each player has received little attention in either biparental or cooperative breeding systems. This project will investigate how parents and helpers in a cooperatively breeding bird, the long-tailed tit Aegithalos caudatus, coordinate their care for offspring in order to resolve conflicts and maximize individual fitness.

The studentship will use data on parental care and fitness from a 25-year study of long-tailed tits, coupled with field observations and experiments, and statistical modeling of investment patterns to achieve the following objectives:

1. To determine whether parents and helpers negotiate care through the coordination of visits to nests

2. To determine the effect of variability in the coordination of care on offspring condition and survival

3. To conduct field observations and experiments to determine the proximate factors affecting coordination of care by parents and helpers

This project will examine patterns of care among parents and helpers, testing multiple hypotheses derived from recent theoretical studies on the causes and consequences of variation in coordination. The student will work on an individually marked population of long-tailed tits near Sheffield for which a detailed database on provisioning behaviour already exists. The student will also conduct novel field experiments and develop statistical models to test hypotheses. This project leads on from recent studies of investment games (Adams et al. 2015) and biparental coordination of care (Bebbington & Hatchwell 2016) in long-tailed tits, and will complement ongoing studies of this species at the study site.