Itahara, A. | bioRxiv Science

bioRxiv2024

Gaze Following in Pigeons Increases with the Number of Demonstrators

Gaze following, orienting ones gaze in the same direction as another individual, is widespread across species and well-studied in terms of cognitive mechanisms. However, the role of collective context on this behavior is less understood. This study tested whether the number of conspecifics looking in a particular direction facilitates gaze following in pigeons (Columba livia). We presented attention-getting stimuli to subsets of pigeons (demonstrators), while other pigeons (observers) could not see the stimuli directly. We used a motion-capture system to track fine-scale movements of head and body orientations. Observer pigeons followed the gaze of demonstrators, specifically toward the target object rather than a perceptually similar distractor. Critically, the likelihood and frequency of gaze following increased with the number of demonstrators looking at the target. We observed no nonlinear effects, such as saturation or quorum thresholds, in this increasing trend, at least under our experimental conditions. In group-living species like pigeons, multiple individuals looking in the same direction may serve as a more reliable social signal. To our knowledge, this is the first study to demonstrate that the number of demonstrators influences gaze following in non- human animals, highlighting the critical role of collective context in animal social cognition.

animal behavior and cognition↗

bioRxiv2023

Gaze tracking of large-billed crows (Corvus macrorhynchos) in a motion-capture system

The visually guided behaviors of corvids (Corvidae) are often examined in previous studies because they provide important clues about their perception, attention, and cognition. However, the details regarding how they orient their heads toward the visual targets (or how they use their visual fields when attending to the visual targets) remain largely unclear. This study used a newly established motion capture system to examine the visual field use of large-billed crows (Corvus macrorhynchos). Study 1 employed an established ophthalmoscopic reflex technique to identify the visual field configuration, including the binocular width and optic axes, as well as the degree of eye movement. Study 2 used the motion capture system to track the head movements of freely moving crows and examined how they oriented their reconstructed visual fields toward attention-getting objects. When visual targets were moving, the crows used their binocular visual fields, particularly around the projection of the beak-tip. When the visual targets stopped moving, crows frequently used non-binocular visual fields, particularly around the regions where their optic axes were found in Study 1 (close to their visual axes). On such occasions, the crows slightly preferred the right eye. Overall, the visual field use of crows is clearly predictable. Thus, while the untracked eye movements could introduce some level of uncertainty (typically within 15 degrees), we demonstrated the feasibility of inferring a crows attentional focus by 3D tracking of their heads. Our system represents a promising initial step towards establishing gaze tracking methods for studying corvid behavior and cognition.

animal behavior and cognition↗