In natural conditions, the daily activity cycle of all galliform birds shows a bimodal pattern. The first peak occurs at sunrise (morning), and the second one in the evening (before sunset). Such patterns are observed in various behaviors (feeding, acoustic activity, aggressiveness, courtship, mating, and territory defense). In Japanese quail kept under two-day and two-night rhythms, the above-mentioned behaviors synchronize with the altered daily rhythms and are performed accordingly.