In this study, an attempt has been made to investigate the relationship of the gonadal-adrenal and pineal glands of the adult male domestic pigeon (Columba livia Gmelin) during their reproductive phases and treated with exogenous melatonin and testosterone propionate. Chapter-I established that the amplitude of the nocturnal peak of melatonin content or AA-NAT activity varies with the seasons in birds housed in the natural environment. In Chapter II, it is widely known that testosterone controls avian behaviours such as singing and being aggressive during the mating season. The gametogenic...