Born to be asocial: newly-hatched tortoises spontaneously avoid unfamiliar individuals

Individual recognition is important for modulating social interactions but it is not clear to what extent this ability depends on experience gained through repeated interactions with different individuals. In wild tortoises, evidence of social interactions is limited to behaviours performed years after hatching, in the context of mating. To investigate the presence of abilities of individual recognition at the onset of life in tortoises, we used hatchlings of two species (Testudo marginata, Testudo graeca) reared with a single conspecific as unique social experience. When located in a novel environment together with the familiar conspecific, tortoises reached the average distance expected by random trajectories. On the contrary, tortoises tested with an unfamiliar conspecific first explored the mate, then actively kept a distance significantly larger than expected by chance. These results show spontaneous abilities of individual recognition in a non-social species at the onset of life, and active avoidance of unfamiliar conspecifics. We suggest that this predisposed behaviour might be adaptive for young tortoises' dispersal.