Meeting Abstract

46.2  Tuesday, Jan. 5  Trade-offs between aggression and parenting in female birds: what’s testosterone got to do with it? CAIN, KRISTAL E*; RICH, MIRIAM S; DAPPER, AMY L; KETTERSON, ELLEN D; Indiana University; Swarthmore College; Indiana University; Indiana University caink@indiana.edu

Males exhibiting parental care generally express an inverse relationship between effort (amount of time, energy, and/or resources) devoted to mate acquisition, and effort devoted to rearing offspring. Testosterone (T) is thought to mediate this trade-off because males with experimentally elevated testosterone (T) often invest more in mate acquisition and less in parenting. A recent study confirmed this relationship in unmanipulated males of a songbird, the dark-eyed juncos (Junco hyemalis). Individual ability to produce T in response to a challenge with gonadotropin releasing hormone (GnRH challenge) was positively related to aggression towards a conspecific intruder, but negatively related to offspring provisioning rates. Less is known regarding the extent to which females face a similar trade-off, and the degree to which T plays a role in mediating aggressive and parental behavior in females. We predicted that if T has similar effects in both sexes, then female behavior should exhibit similar relationships to T, i.e., greater aggression to a conspecific, and reduced parental effort. To test this we measured individual female dark-eyed juncos’ (Junco hyemalis) ability to produce T in response to a GnRH challenges early in the breeding season. Aggression was measured by presenting females with a caged conspecific in the immediate vicinity of the nest early in the incubation period. Parental behavior was measured by quantifying provisioning behavior for four hours early in the nestling period. Results will be discussed in the context of T as a mediator of female behavior and the resolution of the mating/parenting trade-off in females.