Annual histophysiological changes in the adrenal cortex of free‐living blossomheaded parakeets were studied in relation to the gametokinetic activities in the testes and periodic climatic variables to evaluate possible interrelationship, if any, between these endogenous and exogenous cyclic factors. Observations involving histometry, karyometry and lipid cytochemistry of adrenal cortex along with quantitative estimation of tissue cholesterol demonstrate the annual rhythmic pattern in the activity of adrenocortical tissue with an annual peak in February followed by regressive changes till August. Steady progressive changes towards annual peak occur only after November. Results show that the seasonality of the histophysiological features in the adrenal cortex coincides better with the periodic sexual activities of the bird than with any of the surrounding environmental factors.