Individual behavioural rhythmicity is linked to social motivation in Japanese quail

Abstract: This experiment explored links between individual social traits and behavioural rhythms by comparing the feeding activity rhythms of HSR (high social reinstatement) Japanese quail that will cover long distances to reach conspecifics, to those of LSR (low social reinstatement) quail that will cover only short distances to reach conspecifics. We evaluated the functioning of their circadian and ultradian clocks under constant darkness (DD), and then under photoperiodic conditions (LD). Our results revealed that, under DD conditions, the circadian periods of HSR quail were closer to 24h than those of LSR quail. Under LD conditions, the daily rhythm of HSR quail was clearer than that of LSR quail. HSR quail synchronized faster and better to the environmental LD cycle than LSR quail. Our results also showed that, under DD conditions, more LSR than HSR quail expressed ultradian rhythmic phenotypes and that the ultradian rhythm of LSR quail was clearer than that of LSR quail. Under LD conditions, these differences between HSR and LSR quail showed the same tendencies. LSR quail seem to present a more functional ultradian system, and thus could possibly synchronise better on an ultradian environmental cue than HSR quail. Our study demonstrated a link between individual rhythmicity and social traits at an intra-specific level. It revealed complex relationships between ultradian, circadian, and daily rhythms and level of social motivation in Japanese quail. [Copyright &y& Elsevier]