Influence of Odorants on the Behaviour of the Domestic Chick

Abstract

Previous studies have suggested that olfaction influences the development of behaviour in the domestic chick but there has been no detailed investigation of graded responsiveness to odorants of different concentrations or of olfactory memory. This thesis reports research on olfaction in I-day-old chicks, describes experiments that examine concentration-dependent and lateralized responses to a number of odorants. It also reports intersensory effects of stimulation by light on olfactory lateralization and the effects of olfactory experience during development. A new task for testing olfactory responses of chicks was designed and validated. The chicks were presented with a 4 mm diameter coloured bead, at which they pecked readily, affixed to a tube containing odorant. Using this task differential concentration-dependent responses were obtained for 'iso'-amyl acetate, allyl sulfide, ammonia, cineole, limonene, eugenol, methyl anthranilate (MeA) and geraniol. The measures recorded during 10-second trials were pecking and head shaking. Repeated testing of the same chick was made possible by changing the colour of the bead presented together with odorant in each trial, thereby preventing habituation of pecking. It was concluded that presentation of these odorants stimulates receptors (olfactory or trigeminal) within the chick's nasal cavity, rather than receptors in the mouth or eyes, because responses to odorants did not occur following occlusion of both of the chick's nostrils.