Transformation in an endothermic organism at rest in a postabsorptive state measured within its thermoneutral zone. Basal metabolic rate is one of the most widely measured physiological traits,and because this trait represents an animals'maintenance cost, is easy to obtain and believed to reflect the rate of living it has been used to investigate age related charges in energy metabolism. Basal metabolic rate has been found to decline with age in a number of species including human,dogs and passerine birds.Contrary to those findings,BMR has been found to be unaffected by age in naked-mold rats,deer miec and snow petrels. Hence,it is well documented that the relationship between energy metabolism and age differs substantially between species. Intra-specific difference in metabolic change with age on the other hand have been given less attention.