Following opportunity to copulate with a female housed in an adjacent compartment, male Japanese quail spent 64% of their time near a window that provided visual access to the female (Experiment 1). This social proximity behavior persisted for at least 2 weeks of continual exposure to the window despite lack of further physical access to the female (Experiment 2) and was evident at all daylight hours (Experiment 3). Female Japanese quail stimulated more proximity behavior in male conspecifics than did other male Japanese quail or birds of other species (Experiments 4 and 5). However, many characteristics of the female quail were not critical. The female quail did not have to be previous sexual partners, familiar, sexually experienced, or reproductively competent to stimulate proximity behavior in males (Experiments 4 and 5). Experiment 6 demonstrated that the social proximity behavior was primarily a response to the visual aspects of the females. The results are discussed in relation to mate-guarding and surveillance behavior, and implications of the data for sexual classical conditioning of male Japanese quail are noted.

Previous research showed that after opportunity for copulation, male Japanese quail spend about 75% of their time throughout daylight hours near a window that provides visual access to a female conspecific. In Experiment 1 of this study, female Japanese quail typically spent less than 20% of their time near a window that provided visual access to a male conspecific under comparable conditions. In Experiment 2, a small clear plastic cage was placed in a large test arena, and quail were observed when the cage was either empty or contained a sexual partner. Male Japanese quail tended to remain much closer to the cage when it contained a female conspecific than when it was empty. In contrast, the presence of a male did not significantly attract females to the cage area. These findings demonstrate strong sexual dimorphism in the social proximity behavior of Japanese quail. The results are discussed in terms of implications concerning the social structure of Japanese quail and implications for studies of sexual classical conditioning.The research was supported by Gram BNS 8408109 from the National Science Foundation.We are grateful to Camille North and Richard Lyons for their help in analyzing the results of Experiment 2.