Behavioural and physiological effects of testosterone propionate and cyproterone acetate in immature male domestic ducks, Anas platyrhynchos.

The behavioural and morphological effects of testosterone propionate and of the antiandrogen cyproterone acetate were studied in male domestic ducks. Testosterone was also measured by radioimmunoassay in the plasma of these birds to relate the behaviour to the actual circulating levels of hormone. Testosterone stimulates sexual behaviour but has few effects on social displays. There is no correlation between the individual variations of plasma testosterone and sexual behaviour.