Prolactin and avian parental care: New insights and unanswered questions.

Parental care is a critical component of reproductive success for many species, but especially for birds that have high rates of parental care. While ample studies have shown strong, positive correlational relationships between the hormone prolactin and parental care in birds, few studies in a limited number of avian species have performed the causal experiments necessary to elucidate the exact roles of prolactin during these behaviors. Additionally, how prolactin acts in the brain to affect parental behaviors is still virtually unknown with the exception of a small number of studies in very few species. Here, I review what is currently known about prolactin and avian parental care, propose a new hypothesis for prolactin's role in avian parental care, and highlight the gaps in our current understanding of prolactin's role in parental care.