How Many Footsteps Do Dogs Need to Determine the Direction of an Odour Trail?
Peter G. Hepper and Deborah L. Wells
Canine Behaviour Centre, School of Psychology, Queens University Belfast, Belfast BT7 1NN, UK
Dogs have the ability to determine the direction of an odourtrail left by a human. This study examined how much olfactoryinformation from this trail is required by dogs to determinedirection. Six dogs, able to determine direction, were testedon a 21 footstep trail laid on 21 individual carpet squares,one footstep per square, by the same individual wearing thesame shoes. Dogs brought in at right-angles to the trail atits centre were able to correctly determine direction betterthan chance (P < 0.025). Dogs were unable to determine directionwhen the order of the footsteps was randomized by rearrangingthe order of the carpet squares. When the individual odour cuewas removed, but ground disturbance left, dogs were unable todetermine direction, indicating that it was the odour of theindividual that was used to determine direction. In the finalexperiment the number of footsteps made available to the dogwas reduced from 21 to 11 and then 9, 7, 5 and finally 3. Dogswere able to determine direction from 5 footsteps but not 3.It was calculated that it takes 1–2 s for the odour informationin footsteps to change to provide discernible information thatcan be used by dogs to determine direction. The process by whichdogs may determine direction from odour cues is discussed.
Key words: detection, dog, odour trail, olfaction, scent, tracking
Source: Chemical Senses 2005 30(4):291-298