I am interested in the evolutionary significance of armaments and ornaments in females. That is, do females experience sexual selection for exaggerated traits and behaviors that give them an advantage in competition for mates? In my dissertation work, I quantified the fitness costs and benefits of intrasexual aggression in female tree swallows (Tachycineta bicolor). As a postdoc, I will continue to study aggressive behavior in females, focusing instead on underlying neuroendocrine mechanisms. Using the dark eyed junco (Junco hyemalis), I will explore whether behavioral differences among females and between the sexes map onto variation in neural sensitivity to testosterone (e.g. androgen receptor expression).