Divorce in a socially monogamous bird : hormonal mechanisms and reproductive consequences

Zebra finches (Taeniopygia guttata) form long term pairs, within which both sexes contribute to parental care and paired birds raise iterative broods together. In free-living birds, pairs can be disrupted if one member is lost (e.g. to predation). The remaining bird will often pair with a new mate. Pair disruption is known to increase physiological stress as demonstrated by elevated levels of the steroid stress hormone corticosterone (CORT). CORT is an important hormone for maintaining homeostasis, but can negatively impact reproduction by decreasing levels of hormones such as prolactin, which modulate parental behaviors. Although it is known that pair disruption increases CORT in zebra finches, it is currently unknown how this affects prolactin levels and reproductive success. Using a paired design, we examined the effects of pair disruption on parental behavior and reproductive success in zebra finches. Additionally, we examined the specific hormonal mechanisms (prolactin and CORT) that may explain changes in physiology and behavior following pair disruption. Finally, we examined the impact of pair disruption on nestlings by measuring nestling body size and stress (CORT) responses. Taken together, these data provide an integrated examination of how pair bonds in socially monogamous birds affect individual reproductive success, with possible transgenerational consequences.1 page(s