Chronobiology and social life in birds
Abstract
Social motivation and circadian activity rhythms of Japanese quail (Coturnix coturnix japonica) vary greatly from one individual to another. First, we questioned whether social motivation could be linked to individual circadian clock characteristics. We compared quail from two lines divergently selected on the response of their circadian system to constant darkness: quail expressing a robust circadian rhythm (R line) and quail expressing circadian arrhythmicity (A line). Behavioral tests evaluated the social motivation of these birds and revealed that the social motivation of R quail was stronger than that of A quail. Second, we wondered whether the clocks functioning of an individual could predict its integration in a group. We introduced either a R chick or a A chick in stable groups of standard chicks. Ethological observations evaluated spatial proximity and synchronization of the introduced chicks on the activities of the other group members. We found that R chicks were spatially and temporally closer to the other group members than were A chicks. Behavioral tests evaluated interactions of the introduced chicks and the level of their acceptance by the other group members. We found that R chicks were more competent to access food than were A chicks and that separation from the group was more stressful for R chicks than for A chicks. This allowed us to conclude that, in Japanese quail, parameters of social life are linked to the functioning of endogenous clocks.