Conserved abilities of individual recognition and genetically modulated social responses in young chicks (Gallus gallus)

The ability to recognise familiar individuals and the motivation to stay in contact with conspecifics are important to establish social relationships from the beginning of life. To understand the genetic basis of early social behaviour, we studied the different responses to familiar/unfamiliar individuals and social reinstatement in 4-day-old domestic chicks (Gallus gallus) in three genetically isolated breeds: Padovana, Polverara and Robusta. All breeds showed a similar ability to discriminate between familiar and unfamiliar individuals, staying closer to familiar individuals. Social reinstatement motivation measured as the average distance between subjects, latency to the first step and exploration of the arena (a proxy for the lack of fear), differed between breeds. More socially motivated chicks that stayed in closer proximity, were also less fearful and explored the environment more extensively. These results suggest that modulation of social behaviour shows larger genetic variability than the ability to recognise social partners, which appears to be an adaptive ability widespread at the species level even for very young animals.