Birds have been shown to use their olfactory system for predator detection and orientation, and also social and foraging tasks. They have fully functioning olfactory systems and each individual bird has a distinct body odor. This study used carrion crows, which are a species that live in complex social societies. In order to be successful in the complex social environment in which they live, carrion crows have been found to rely heavily on visual and acoustic cues. Little research has been done of the use of olfactory signals in birds. This study investigated whether carrion crows respond behaviorally to olfactory cues of the same species. They also looked at whether carrion crows prefer to turn towards familiar or unfamiliar individuals based on scent. The birds were expected to orient towards the odor of an individual of the same species and avoid the odors of unrelated species.
The results found that carrion crows were observed less often close to the scent of their same species rather than the control scent (Fig 1). The scent was collected by putting the birds in a cotton bag, which could have been a stressful environment. Males showed less avoidance towards the scent of a familiar individual (Fig 2).
The results did not support the hypothesis that the carrion crows oriented towards the scent of the same species. Since the scent was collected while the bird was in a bag and most likely stressed, the results suggest that the general avoidance of the scent side was due to a dislike for a stressed bird of the same species. The fact that males showed less avoidance towards the familiar scent might mean that they have a stronger interest in conveyed information or they are more willing to provide social support.
Researchers originally thought that chemical communication was only a minor contributor to bird species survival. However, recent studies have begun to show that birds rely heavily on their olfactory system. Olfaction plays a significant role in bird migration and is also important in competitive environment. It could be useful to detect stressed birds of the same species if a predator is near. Learning more about the role of olfaction in a species like the carrion crows could help discover more about the mechanisms that control the social living situation of birds that live in groups.
Reference: Wascher, C. A. F., Heiss, R. S., Baglione, V., Canestrari, D. (2015). Behavioural responses to olfactory cues in carrion crows. Behavioral Processes, 111: 1-5.