Direction indicator and magnetic compass-aided tracking of the sun by flamingos?

Abstract. Animals use to align their body axis with respect to different cues (e.g. sun position, wind direction, magnetic field lines) and signals (informing about source of interest) in diverse behavioural contexts. Existence of alignment indicates ability to sense such cues or signals and its study can enlighten the mechanism of their sensing. Global cues (sun position, magnetic field) might provide a directional reference (direction/heading indicator) for organization of the mental map and/or for coordinated take-off. The existence of a common direction indicator may be of importance especially in birds living in large colonies and having impeded maneuverability. We measured the direction of the body axis (alignment) in flamingos of four species at 18 localities in zoological gardens and in the wild in altogether eight countries during different seasons of the year and at different times of the day. The measurements were taken from photographs in a blinded way. Flamingos in Europe showed a significant preference to align towards South during all recorded stationary activities (grooming, resting, standing) while those from Kenya tended to head towards North. On the contrary, the distribution of body alignments during locomotor activities (walking, wading, feeding) was random. Under overcast weather, and especially in the morning hours, magnetic South or North were better predictors of heading than sun position. We interpret our findings as evidence for a magnetic alignment in flamingos (depending on the weather condition) and suggest that its main function might be seen in information rather than in energy interaction. Under windless conditions, sun position and magnetic field may provide a common reference direction, i.e. a direction indicator. Visual cues (if available) and vision are in birds probably more dominant in spatial orientation than magnetic cues and magnetoreception. Magnetoreception might be “switched on”, when visual sensing of relevant cues is impeded.