Do domestic hens discriminate between familiar and unfamiliar conspecifics in the absence of visual cues?

Abstract

Domestic fowl ( Gallus gallus) are able to discriminate between familiar and unfamiliar conspecifics, at least if they may rely on visual, auditory and olfactory cues from live stimulus birds. The Red Junglefowl, the ancestor of the domestic fowl, inhabits woody and bushy areas and the edge of jungles where sight is restricted by dense vegetation. Consequently non-visual communication is more suited to such an environment than is visual communication. Individual non-visual recognition would enable the birds to maintain their group and social structure despite the complex nature of the environment. In the present study, we test if domestic chickens do discriminate between familiar and unfamiliar conspecifics in the absence of visual cues. We carried out two preference experiments. In each test, two live stimulus hens, one familiar and one unfamiliar, were presented to a test hen. In the first experiment, the hens were separated only by wire-mesh, allowing the test hen to receive visual as well as auditory and olfactory stimuli from the stimulus hens. In the second experiment, visual contact between the hens was prevented by replacing the wire-mesh with an opaque black cloth. As a measure of preference the aggregation time with the familiar and the unfamiliar bird was recorded. In the first experiment, hens showed significant discrimination between familiar and unfamiliar conspecifics. However, hens in two experimental series showed different directions of preference. In the second experiment, where test hens had to rely on non-visual cues, no significant discrimination between familiar and unfamiliar conspecifics was observed.