Red foxes may use Earth’s magnetic field to enhance hunting success
Red foxes, Vulpes vulpes (Carnivora - Canidae) hunting rodents show a specific behavior known as ‘mousing’. The fox jumps high, so that it surprises its prey by striking from above. Prior to an attack, foxes move forward very slowly and deliberately, with ears erect, cocking their heads from side to side indicating that they are paying careful attention to auditory cues. However, the body direction of foxes as they attack are non-random.
Field research observing mousing behavior in wild red foxes, and recording the body orientation of foxes while preparing for a jump, showed that a large majority of successful attacks in high cover were north-east-oriented jumps, while attacks in other directions were largely unsuccessful.
This north-east preferred attack directions cannot be explained by an effect of light cues since observations were carried out at different times of day, at different seasons of the year, under overcast and clear skies. Nor was this clustering a response to wind direction, which varied from observation to observation.
When hunting for prey in high cover or under snow, foxes are unable to use visual cues to augment auditory cues to target prey. So, directional heading has a profound effect on hunting success under such conditions. In low vegetation, where the prey can be spotted also by sight, directional heading seems to play a less decisive role.
In the absence of any other source of directional information that can explain the non-random alignment of fox predatory attacks and, in particular, the precise alignment of successful attacks on prey in high cover and under snow, it was proposed that these responses are a case of alignment with respect to the geomagnetic field (GMF).
Furthermore, a fox that approaches an unseen prey along a northward compass bearing could estimate the distance of its prey by moving forward until the sound source is in a fixed relationship to the magnetic field, e.g. it coincides with the inclination of the magnetic field.
Thus, when visual information is limited, using the magnetic compass to provide a more accurate estimate of distance from the prey could account for the dramatic increase in predatory success of attacks aligned to the north and south field. If so, this would be the first documented case of an animal using magnetic compass input to estimate distance, rather than direction.
Reference: Červený, J., Begall, S., Koubek, P., Nováková, P. and Burda, H. (2011). Directional preference may enhance hunting accuracy in foraging foxes. Biol. Lett. 7, 355-357. Abstract/FREE Full Text
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