23.6 Friday, Jan. 4 Interspecific brood parasitism prolongs parental care and increases the stress response in a tropical songbird MARK, MM*; RUBENSTEIN, DR; Columbia University; Columbia University firstname.lastname@example.org
Interspecific brood parasitism in birds negatively affects parental fitness by reducing current reproductive success, but its impact on future reproduction has been rarely tested. Glucocorticoid stress hormones often mediate the trade-off between current and future reproduction by mobilizing resources towards parental care or self-maintenance. To determine if brood parasitism alters the trade-off between current and future reproduction, we measured parental care behavior and glucocorticoid levels in nestlings in the Neotropical host-parasite system of the striped cuckoo (Tapera naevia excellens) and the rufous and white wren (Thryophilus rufalbus) during three reproductive stages: incubation, nestling, and fledgling. We found that foster parents of cuckoo chicks had significantly higher levels of stress-induced, but not baseline, corticosterone during the post-fledging stage. Higher maximal levels of stress-induced corticosterone were associated with an increase in parental care. Foster parents delayed re-nesting due to prolonged care of a cuckoo chick and were less likely to return to nest the year following a parasitism event. Together, these results suggest that foster parents express higher parental investment in cuckoo chicks than their own chicks, mediated by corticosterone, and that parasitism reduces opportunity for future reproduction.