Begging for answers: How do parents and helpers respond to offspring begging in a cooperatively breeding system?

In species that provide parental care, parent-offspring conflicts may arise due to the difference between the optimal amount of care that parents should provide from the offspring perspective and from the parents perspective. A good example is parental provisioning in passerines, where there is an ongoing interaction between food demand by begging and the parental response in terms of food provisioning. Conflicts between parents are also expected as each bird should be under selection to minimize its personal effort by trying to shift the greatest possible workload towards its partner. Theory predicts that females may be able to manipulate paternal contribution using maternal effects, specifically by altering androgens levels of the eggs, but few empirical studies have been conducted to test this prediction. In cooperatively breeding systems, where non-breeding ‘helpers’ also provide care to the brood, this conflict may extend to the rest of the breeding group. For example, conflicts may occur between parents and helpers (and among helpers) about how much care to provide, since each individual should be under selection to minimize its workload and leave as much care as possible to the other group members. In this case, females may be expected to attempt to exploit not only their partners, but also the helpers, and in particular the helpers that are unrelated related to them. In the sociable weavers, Philetairus socius, previous work has found that females use the presence of helpers to decrease their own investment in reproduction. Specifically, females with more helpers laid smaller eggs, with lower yolk hormonal levels, and produced offspring that begged at lower rates. The aims of the present study were to follow up on these previous results and further explore the possibility of females influencing conflicts over food provisioning through maternal effects. Specifically to explore 1) if there were differences in the way parents and helpers responded to the begging behaviour of the nestlings and 2) whether nestlings begged in the same fashion towards different classes of birds. The workload of each carer was assessed, their status was attributed (distinguishing breeders by sex and helpers by kin relationships towards offspring and female breeders) and the begging they received was measured (defined by call rate and frequencies). The general results were consistent with the predictions. Birds exposed to higher rates of begging took less time to come back with food and male breeders displayed the highest feeding levels. Begging rate seemed to honestly signal nestlings’ hunger as it was positively correlated with their last feeding and the time of the day, but call rate was not significantly different regarding different classes of birds. All the birds responded in the same way to an increase in begging rate. Finally, parents were the FCUP Begging for answers: How do parents and helpers respond to offspring begging in a cooperatively breeding system? iv ones exposed to the highest frequency calls. This study emphasises the importance of exploring the interactions between offspring demand and provisioning rules among cooperatively breeding systems, with more complex nets of family interactions to better understand the resolution of family conflicts and their underlying mechanisms.