Considerations on the role of olfactory input in avian navigation

Abstract

A large amount of data documents an important role of olfactory input in pigeon navigation, but the nature of this role is not entirely clear. The olfactory navigation hypothesis assumes that odors are carrying essential navigational information, yet some recent experiments support an activating role of odors. This led to an ongoing controversy. An important, often-neglected aspect of the findings on olfaction is that olfactory deprivation affects avian navigation only at unfamiliar sites. The orientation of anosmic birds at familiar sites remains an enigma; earlier assumptions that they would rely on familiar landmarks have been disproven by the home-oriented behavior of anosmic pigeons additionally deprived of object vision, which clearly indicated the use by the birds of non-visual, non-olfactory cues. However, if odors activate the establishing and enlarging of the navigational 'map' and promote the integration of local values of navigational factors into this map, it seems possible that such a process needs to occur only once at a given site, when the birds are visiting this site for the first time. If that were the case, the birds could interpret the local factors correctly at any later visit and orient by them. This hypothesis could explain the oriented behavior of birds at familiar sites, and it could also help to reconcile some of the seemingly controversial findings reported in the literature, where the effect of olfactory deprivation was reported to differ considerably between the various pigeon lofts, possibly because of different training procedures.

Parvalbumin‐immunoreactive cells in the olfactory bulb of the pigeon: Comparison with the rat

“…For olfactory function, it has widely been studied that the regulation of instinctive behaviours and emotions is considerably dependent on olfactory sense in a great part of rodents (Saraiva et al, ; Stowers, Cameron, & Keller, ). In birds, recent studies have been suggesting that odours contribute to orientation and navigation (Jorge, Marques, Pinto, & Phillips, ; Wiltschko & Wiltschko, ). Therefore, parvalbumin distribution in avian OBs might be different from that in rodent OBs.…”

Co-opting evo-devo concepts for new insights into mechanisms of behavioural diversity

“…Multiple sensory cues contribute to orientation in pigeons (Gagliardo et al, 2016;Wiltschko and Wiltschko, 2017).…”

Olfactory navigation versus olfactory activation: a controversy revisited

“…We find the olfactory-activation hypothesis attractive because assuming that an activation is necessary only once when the bird is new at a site, it can explain a number of observations that the olfactory-navigation hypothesis left unanswered, like: the lack of an effect of olfactory deprivation at familiar sites, the expansion of that 'familiarity' beyond the site itself, and the difference between the findings at the different lofts, which can be attributed to the extent of early training (see Wiltschko and Wiltschko 2017 for a more extended discussion).…”