Social motivation does not go hand in hand with social bonding between two familiar Japanese quail chicks, Coturnix japonica

Social bonds between conspecifics (sexual pairmates, parent–infant or siblings) and social motivation can influence the way birds interact. Social bonds between familiar conspecifics may also be formed, especially in chicks from precocial species in which behaviour is characterized by a strong social attraction. We investigated the establishment of such a bond and the effect of social motivation using a separation/reunion test in 1-week-old Japanese quail. In experiment 1, the behaviour of paired quail selected for high (HSR) or low (LSR) social reinstatement behaviour was recorded during three successive 10 min situations: baseline, separation and return of the cagemate. Both lines showed behavioural changes during social separation but the distress response was higher in the HSR line. Return of the familiar cagemate induced a return to baseline activity in both lines. The specificity of this response was tested in experiment 2 in which paired quail of both lines were separated, and their behavioural and vocal responses to the introduction of the familiar or an unfamiliar bird were compared. LSR chicks responded differently both behaviourally and vocally according to the familiarity of the introduced bird, whereas the response of HSR chicks differed only for aggressive pecks. HSR quail chicks thus revealed a nonspecific social attraction for conspecifics, whereas LSR chicks showed a bond with the cagemate. Our results highlight the importance of vocal communication as an indicator of the strength of the bond. Our findings show that high social motivation in quail chicks is not related to the development of a social bond.