Testing the flexibility of fasting-induced hypometabolism in birds: effect of photoperiod and repeated food deprivations

We tested whether photoperiod and repeated fasts modulate the fasting-induced nocturnal hypometabolic response in Japanese quails and pigeons. Quails did not compensate a shorter dark phase by a deeper hypothermia, but instead showed diurnal hypothermia that seemed to be conditioned by the removal of food. Body mass loss measurements indicated that this response saved energy. Repeated fasts in constant photoperiod in quails and pigeons slightly augmented the hypometabolic response only in quails. During fasting intervals, body mass increased in pigeons, but decreased in quails. Apart from the diurnal hypothermia seen in quails, photoperiod and repeated fasts had little influence on fasting-induced hypometabolism.