Circadian rhythms play a fundamental role in the migratory patterns of birds, aligning their physiological and behavioral processes with environmental changes. These rhythms, governed by internal biological clocks, are influenced by external factors such as photoperiod, temperature, and food availability. This paper delves into the mechanisms behind circadian regulation in migratory birds, examining how these rhythms facilitate seasonal migration, fat deposition, and behavioral adaptations. The paper also addresses emerging challenges, particularly the impact of climate change and habitat loss on the circadian systems of migratory species. Understanding these mechanisms is critical for predicting how migratory birds might adapt to a changing world and for informing conservation efforts.