Wolfgang Goymann Max Planck Institute for Ornithology, Andechs, D Title Hormones, aggression and dominance Abstract The relationship between hormones and behaviour can be complex. In the past, hormones have been viewed as deterministic and causal agents of behaviour. Today, a more probabilistic view of hormones has been established, according to which hormones increase the likelihood of a behaviour – given the context is right. The reciprocal is also true: behaviour and in particular social interactions can have profound effects on hormone secretions. I will review the current evidence for social modulation of androgens in birds and try to come up with ideas to modify and specify the predictions of the challenge hypothesis (Wingfield et al. 1990). This hypothesis provides a conceptual framework for the relationship between social factors and endocrine responses. More than 25 years after its formulation we understand many, but by far not all differences in androgen secretion patterns of male vertebrates. The situation for females is even more complicated: female vertebrates show aggressive behaviours just as males do. Yet, we still know little about hormonal modulation of female aggression or the effect of aggressive interactions on hormone concentrations in females. I will review the available literature and present and discuss findings from black coucals, a sex-role reversed bird species, in which females are polyandrous, sing and defend large territories, whereas males provide all the parental care. CV Professional experience 2004-present Senior Research Scientist and Local Head of the Department of Biological Rhythms & Behaviour, MPI for Ornithology, Andechs, Germany 2003-2004 Research Scientist, Group Leader Endocrinology, Department of Biological Rhythms & Behaviour, MPI for Ornithology, Andechs, Germany 2001-2002 Post-Doctoral Research Associate, Department of Zoology, University of Washington, Seattle, USA 2000 Post-Doctoral Researcher, Max Planck Research Centre for Ornithology, Andechs, Germany Education 1996-2000 PhD in Zoology, Ludwig-Maximilians-Universität München, Germany 1995 Diploma in Biology, Ludwig-Maximilians-Universität München, Germany 1991-1995 Study of Biology (Neurobiology, Ecology, Biochemistry), Freie Universität Berlin and Ludwig-Maximilans-Universität München, Germany Institution address Wolfgang Goymann Department for Biological Rhythms and Behaviour Max Planck Institute for Ornithology Von-Der-Tann-Str. 7 D-82346 Andechs Germany goymann@orn.mpg.de http://orn.mpg.de/mitarbeiter/goymann.html