Learning and male–male sexual competition in Japanese quail (Coturnix japonica).

Male Japanese quail (Coturnix japonica) were trained individually to discriminate between 2 sounds presented at opposite ends of an outdoor aviary. One of the sounds (the positive conditioned stimulus [CS+]) was associated with the release of a female, and the other (the negative CS [CS-]) was presented alone. Which of the 2 sounds served as the CS+ (and which served as the CS-) was counterbalanced across subjects. The subjects came to approach their CS+ but did not move away from their CS-. After having been conditioned individually, the subjects were tested in pairs, with a single female released after the presentation of a stimulus that was the CS+ for one of the males and the CS- for the other male. During most of these tests, the male for whom the prefemale stimulus was the CS+ copulated with the female before the male for whom the prefemale stimulus was the CS-. These results indicate that learning can have an important role in competition for access to a reproductive partner.