Rb. D'Eath et Rj. Stone, Chickens use visual cues in social discrimination: an experiment with coloured lighting, APPL ANIM B, 62(2-3), 1999, pp. 233-242
In an experiment to investigate the cues used in social recognition by layi
ng hens, visual cues were manipulated by altering the illumination. Hens fr
om small flocks were allowed to choose to approach and feed next to a flock
mate or an unfamiliar hen. The effect of dim and coloured lighting on this
discrimination was investigated in a choice arena. The apparent brightness
to the hens of three colour treatments (white, red and blue) were equalised
at two brightness levels, comparable to the home pen (approximately 77 lux
) and to conditions on a commercial farm (approximately 5.5 lux). On the ba
sis of feeding preferences and aggressive interactions, hens discriminated
between familiar and unfamiliar birds at levels above chance in only the br
ight white treatment. Subjects chose familiar hens over unfamiliar hens mos
t frequently under white lights, and least often under red. Brightness did
not significantly affect choice. Subjects' general activity (measured as ei
ther distance moved or time until a social choice was made) was unaffected
by the lighting treatments. The results show for the first time that visual
cues are important in social recognition in small flocks of laying hens. P
ossible implications for the welfare of hens kept under commercial conditio
ns are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.