Acoustic communication in zebra finches signals when mates will take turns with parental duties

Bi-parental care may involve both cooperation and conflict between parents. Parents adjust their workload to that of their partner and this ability is likely to affect reproductive success. Whether mates communicate, either to resolve the sexual conflict or to coordinate their joint investment in parental care is a largely unaddressed question which we examined by recording wild zebra finches at the nest during incubation. Zebra finch (Taeniopygia guttata) partners produce vocal exchanges at the nest that can be characterized as duets. Some duets end in nest-relief (when birds take turns incubating and foraging) but some do not (when the foraging mate vocally interacts with its incubating partner by coming inside or in the vicinity of the nest). Our data indicate that the structure of the duet predicted its outcome (relief or not), with a parent calling differently before leaving or staying in the nest by modifying its vocal repertoire as well as the acoustic structure of one particular call type which is typically used inside the nest. Zebra finch partners may thus exchange on the time to take turns with parental duties. Our results show that acoustic communication between partners might be of importance in the organization of parental care and could help in understanding sexual conflict resolution or cooperation phenomena in future studies.