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Published on: May 11, 2016
Castration does not decrease nonreproductive aggression in yearling male European starlings (Sturnus vulgaris)
Rianne Pinxten1, Elke De Ridder, Maarten De Cock
1Department of Biology, University of Antwerp, U.I.A., B-2160 Wilrijk, Belgium. pinxten@uia.ua.ac.be
Hormones and Behavior
|April 16, 2003
Summary
Castration increased aggression in male European starlings during the nonbreeding season. This suggests that nonreproductive aggression in these birds is independent of testosterone levels.
Area of Science:
- Animal Behavior
- Endocrinology
- Avian Biology
Background:
- Nonbreeding season aggression in birds can occur despite low testosterone levels.
- This suggests that nonreproductive aggression may be independent of gonadal sex steroids.
Purpose of the Study:
- To investigate the effect of castration on nonreproductive aggressive behavior in yearling male European starlings (Sturnus vulgaris).
Main Methods:
- Castrated (Cx) and control (C) male starlings were paired in dyadic trials across three periods.
- Aggression was quantified by observing competition for nest box access using infrared cameras.
Main Results:
- Castrated males exhibited higher aggression levels than control males across all periods.
- Aggression in castrated males was significantly higher than controls when all periods were analyzed together.
- Aggression was independent of testosterone levels, and castration even appeared to increase it.
Conclusions:
- Nonreproductive aggression in yearling male starlings is independent of gonadal sex steroids.
- Castration may enhance nonreproductive aggression in this species.
