Olfaction and behavioral modification in domestic chicks (Gallus domesticus)

Olfactory responsiveness in the female domestic chick was examined in a series of experiments. Individually-housed chicks preferred the familiar soiled substrate from their own home box to that soiled by a strange conspecific and to clean wood litter when placed in an otherwise novel Y maze. An artificial odorant present during the development of group-reared chicks subsequently proved attractive in an otherwise novel and potentially frightening situation. Chicks reared with one of two aromatic oils subsequently discriminated between them and preferred the familiar oil when both were present in the test box. The preferences are likely acquired because naive, one-day-old chicks reacted similarly to wood litter treated with either water or oil. Presence of a familiar rearing odor also reduced fear of a novel open field. In contrast to controls, chicks whose nostrils were blocked prior to rearing with an aromatic oil showed no subsequent preference for this odorant. The present results suggest that domestic chicks can regulate their behavior in response to olfactory cues though trigeminal chemoreception may also be involved.