Laying hens do not discriminate between video images of conspecifics

Abstract

In a study of social recognition in domestic hens, Gallus gallus domesticus, the suitability of video images as social stimuli was investigated. With live birds behind clear Perspex as stimuli, hens took longer to begin feeding near unfamiliar conspecifics than flockmates, and also discriminated between dominant and subordinate flockmates. When life-size colour video sequences of the same birds were substituted, however, there was no discrimination on the basis of either familiarity or rank, although hens took longer to begin feeding near to videos showing hens with a threat-like posture than hens with normal posture. In a second video experiment, hens again failed to discriminate flockmates from unfamiliar birds. Behavioural observations showed that in early trials, subjects appeared to attend to the stimulus and occasionally moved in synchrony with the video bird or pecked at its head. In later trials these responses were never seen, and hens approached the screen more readily. Despite these behavioural changes, discrimination of flockmates from unfamiliar birds was not found at any stage. Various possible reasons for this failure to discriminate between familiar and unfamiliar conspecifics on video are discussed, and the findings contrasted with other published work in which videos were shown to be adequate substitutes for social stimuli in fowl ( Gallussp.).