Classical conditioning increases reproductive success in Japanese quail, Coturnix japonica

We examined the adaptive significance of learning by determining whether classical conditioning increases reproductive success. Male and female quail received conditioning trials in which a small light (conditioned stimulus or CS) signalled access to a copulation partner. After this learning experience, pairs of subjects received a single 2-min (experiment 1) or 5-min (experiment 2) copulation test during which both the female and the male, only the female, only the male, or neither bird received the conditioned stimulus signalling access to a copulation partner. Signalling the copulatory episode for both the female and the male significantly increased the percentage of fertilized eggs that were produced and increased the efficiency of the copulatory behaviours that occurred. Presenting the CS to just one or the other sexual partner had no effect. These findings demonstrate that classical conditioning can enhance reproductive success, but the effect requires that both the male and the female be able to anticipate a sexual encounter. (c) 2004 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.