Female presence affects male behavior and testosterone levels in the European starling (Sturnus vulgaris).

In this study, we confronted individually housed male European starlings (Sturnus vulgaris) with a female conspecific for 60 min to study the consequences on behavior and plasma testosterone (T) concentrations. Control males experienced a similar procedure, the only difference being that they were tested in the absence of a female. Female presence significantly affected both behavior and plasma T levels of male starlings.

Castration does not decrease nonreproductive aggression in yearling male European starlings (Sturnus vulgaris).

In the nonbreeding season, some bird species express high levels of aggression despite basal plasma testosterone (T) concentrations. Consequently, nonreproductive aggression is believed to be independent of plasma T. In the present study, we investigated the effect of castration on nonreproductive aggressive behavior in yearling male European starlings (Sturnus vulgaris).

Context-dependent effects of castration and testosterone treatment on song in male European starlings.

Most seasonally breeding songbirds display dramatic seasonal fluctuations in plasma testosterone (T) levels and mate attraction behaviors, including song. However, males of some songbird species, such as the European starling (Sturnus vulgaris), continue to sing at high levels after the breeding season, when T levels are basal. In male starlings song during the breeding season functions mainly to attract mates, whereas song during the nonbreeding season appears unrelated to reproduction.