Olfaction in petrels: from homing to self-odor avoidance.

In the 1960s, Betsy Bang unraveled the complexity of the olfactory apparatus of procellariiform seabirds (petrels and albatrosses), suggesting an important role for olfaction in their ecology. Shortly thereafter, Prof. B. Wenzel continued the investigations on petrels' well-developed olfactory neuroanatomy as well as their sensitivity to food-related scents. Later studies demonstrated further that the sense of smell is also critical to these birds when homing to their burrow. Building on these findings, we have demonstrated in several petrel species the importance of the burrow olfactory signature in homing. The nature of this olfactory signature relies predominantly on their mate's odor. Indeed, in our Y-maze experiments, Antarctic prions (Pachyptila desolata) and blue petrels (Halobaena caerulea) could discriminate between their own and their mates' odors. However, although they are attracted by their mate odor, they prefer the odor of a conspecific bird to their own. These results have drawn attention to the possible use of chemical signals in birds' social behaviors, such as individual recognition and/or mate choice. Indeed, petrel life history traits suggest that olfactory-mediated mate choice may have evolved in this group to ensure genetic compatibility between mates. We have recently shown that a bird's semiochemical profile is more similar to itself, year after year, than to that of a conspecific. As a result, a novel function of olfaction emerges in petrels: the perception of a chemical signal that may broadcast individuals' identity and quality, thereby contributing to an optimal mate choice.