Meeting Abstract

S3.10  Sunday, Jan. 4  Hormones, sex roles, and performance GOYMANN, Wolfgang; Max-Planck-Institut fuer Ornithologie goymann@orn.mpg.de

Testosterone is a key hormone related to reproductive aggression in male birds and some experimental evidence suggests that additional testosterone may increase performance of reproduction-related traits in free-living male song sparrows, white-crowned sparrows and dark-eyed juncos, i.e. testosterone-treated birds enlarged their territories or gained extra-pair fertilizations. On the other hand, testosterone decreased paternal care in these species, indicating a potential trade-off between the performance of different traits related to reproduction. External testosterone has been demonstrated to activate or increase behavioral traits such as song and aggression in females of bird species in which females normally do not show such behaviours. Hence, one may naively expect that in sex-role reversed species in which females sing and defend territories or mates such behaviors may be controlled by testosterone as well. Evidence for this is, however, limited. Because high levels of testosterone may interfere with the reproductive physiology of females, other mechanisms may have evolved to hormonally control sex-role reversal. In this talk I will look at hormonal factors that may promote resource-defense aggression in sex-role reversed female birds and that may promote female or male parental care and reproductive success.