The Dietary Energy and Nitrogen Requirements of the Gray-Headed Flying Fox, Pteropus-Poliocephalus (Temminck) (Megachiroptera)

Abstract

The maintenance energy (MER) and nitrogen (MNR) requirements of Pteropus poliocephalus were determined from a series of feeding trials with artificial diets. The low basal metabolic rate (BMR: 225 kJ.kg-0.75.d-') of this bat is associated with a low MNR (457 mg. kg-0.75.d-') but does not reflect a low MER (667 kJ.kg-0.75.d-'). From flight data of Carpenter and the MER from this study, a minimal field energy budget was calculated to be 944 kJ. .d-'. This value is high compared to that of microchiropteran bats. Studies of the digestibility of two fruit diets, native fig and apple, showed that more energy than nitrogen was apparently absorbed. The latter is a limiting nutrient in the apple diet, so that 3.2 times as much dry matter must be consumed in order to meet the nitrogen requirement as for the field energy requirement. It is postulated that the low BMR and low MNR are associated with an interrupted or restricted source of dietary nitrogen. A high MER may provide a means by which surplus energy is dissipated as heat. An ititake of excess energy in order to meet nitrogen requirements also explains how P. poliocephalus can afford a high field energy budget.