Sex differences in parental response to offspring begging are associated with pair bond strength across birds

Mothers, fathers, and offspring clash over how much care offspring receive. Offspring beg to solicit more food — but how much begging is rewarded can depend on who is listening. While both parents benefit from provisioning offspring, each benefits from their partner shouldering more of the burden of care, leading to sexual conflict. Additionally, if the costs and/or benefits of provisioning differ by sex, parent–offspring conflict should vary by sex. Whether there are sex differences in males’ and females’ responses to begging in birds, and to which extent evolutionary conflicts affect sex differences in parental response to begging, is not known. We therefore conducted a meta-analysis on 31 bird species, comparing sex differences in parental responses to begging to social and physiological traits that may influence conflict. Within species with stable bonds and/or low extra-pair paternity, and thus lower sexual and paternal-offspring conflict, males’ provisioning effort is more strongly correlated with offspring begging than females’. The opposite holds within species that change partners between breeding bouts and/or have high extra-pair paternity: females respond more to begging, perhaps compensating for males’ lower responsiveness. These results suggest that sex differences in parent–offspring communication can emerge from both sexual and parent–offspring conflict.