Discriminating the sex of conspecifics by male Japanese quail (Coturnix coturnix japonica).

How male Japanese quail (Coturnix coturnix japonica) discriminate the sex of conspecifics at a distance was investigated by testing subjects with male and female stimulus birds on the other side of a small window after opportunities to copulate with females and again after repeated exposures to males in the absence of copulatory opportunity. Time spent near the window, frequency of window approaches, duration of window visits, rate of walking near the window, line crossings outside the window area, pecking the window, and crowing were measured. Subjects responded similarly in the presence of male and female stimulus birds during the first test block but discriminated the sex of conspecifics after noncopulatory exposures to males. The discrimination was evident in less locomotion and less crowing in the presence of females as compared with males and, as predicted by a discrimination learning hypothesis, developed largely through a change in responding to males.