Avian Circadian Rhythms

In the late 1980s and early 1990s we were the first lab to show that physiological levels of melatonin were both necessary and sufficient to drive circadian rhythms of feeding and locomotion in the homing pigeon, Columba livia. This study was based on our findings that the pineal gland and eyes were sources of melatonin in pigeons and that the implantation of melatonin capsules suppressed these rhythms. Later, we also showed that constant bright light, as perceived by the eyes, could override these melatonin-driven circadian rhythms.