Social behaviour studies on domestic animals. I. Hens in laying cages

Abstract

The social ranks of neighbouring birds in a laying cage plant were determined by paired encounters. It was found that a definite social structure existed in the cages. Three strains of birds originating from the same population were used in the experiment, and found to differ in social rank as well as production. Social rank affects early egg production by delaying the onset of sexual maturity, but does not appear to affect intensity of lay, the social effect apparently occurring only when birds are first housed. The effect of social rank is not only on the mean but also on the variance, low-ranked birds being slower to mature and also more variable in the age at which they begin to lay. The applications of these results to strain testing and cage design are discussed.