Forty years ago, Papi and colleagues discovered that anosmic pigeons cannot find their way home when released at unfamiliar locations. They explained this phenomenon by developing the olfactory navigation hypothesis: pigeons at the home loft learn the odours carried by the winds in association with wind direction; once at the release site, they determine the direction of displacement on the basis of the odours perceived locally and orient homeward. In addition to the old classical experiments, new GPS tracking data and observations on the activation of the olfactory system in displaced pigeons have provided further evidence for the specific role of olfactory cues in pigeon navigation. Although it is not known which odours the birds might rely on for navigation, it has been shown that volatile organic compounds in the atmosphere are distributed as fairly stable gradients to allow environmental odour-based navigation. The investigation of the potential role of olfactory cues for navigation in wild birds is still at an early stage; however, the evidence collected so far suggests that olfactory navigation might be a widespread mechanism in avian species.
No competing interests declared.
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
- Deprived of the sense of smell.
- A behavioural mechanism allowing the selection of a specific direction in space on the basis of an external reference, such as the sun azimuth and the geomagnetic field.
- A cell of the immune system.
- Navigational map
- A behavioural mechanism allowing a subject to establish the current position with respect to the goal on the basis of environmental cues.
- Piriform cortex
- The region of the brain, more precisely of the telencephalon, that receives direct input from the olfactory bulb. The piriform cortex is involved in the discrimination and memorization of odour stimuli.
- Trigeminal nerve
- The fifth cranial nerve. It has three branches, with sensory (the ophthalmic nerve and the maxillary nerve) or sensory-motor (the mandibular nerve) functions.
- True navigation
- The ability of a subject to reach a goal by calculating the goal position on the basis of local cues [the ‘map step’, according to Kramer's definition (Kramer, 1953)] and by determining the goal direction in space (the ‘compass step’, according to Kramer's definition).
- Vanishing bearing
- The direction of a released bird when vanishing from the observer's view at the release site.
- An immediate early gene rapidly expressed in response to external stimuli. An increased expression of the ZENK protein in certain brain regions can be directly linked to neuronal activity.
- © 2013. Published by The Company of Biologists Ltd