The cost of forward flight for a 11.7 g nectar-feeding bat Glossophaga soricina (Phyllostomidae; Glossophaginae) was estimated to be 5.888 kJ h -1 (1.63 W). To obtain this estimate, we quantified the amount of time allocated to specific activities and the animal´s daily energy intake in captivity for 17 separate 24-hour-periods. These data were arrangedin a set of daily energy-balance equations with the energy coefficients for each activity as unknown parameters. These equations were solved for the unknown coefficients b ymultiple lonear regression analysis. Using our estimate of flight cost and values for daily energy expenditure from the literature, we estimated how a free-ranging nectar-feeding bat allocates time and energy among different activities.