Is protein content in the diet of Wahlberg’s epauletted fruit bats, Epomophorus wahlbergi, important?

Abstract

Wahlberg’s epauletted fruit bat, Epomophorus wahlbergi, feeds on a range of fruit, nectar, pollen and flowers. Frugivores may have difficulties in maintaining their protein requirements since fruit are generally high in sugar content but low in protein content. Some studies have found that fruit bats obtain most of their food protein when feeding on a variety of fruits. We investigated if E. wahlbergi prefers additional protein to sugar-only nectar solutions. They were offered equicaloric 15% glucose solutions with varying protein concentrations (2.58, 5.68, 7.23 g soy protein/kg H₂O) and a solution with no protein. This was repeated using 15% sucrose instead of glucose solutions. Epomophorus wahlbergi’s volumetric intake of the respective glucose and sucrose solutions varied among individual bats, with total volumetric intake being highest for solutions with no protein. This suggests they have low protein dietary requirements, which may be a response to the low-protein fruit available in the wild. Alternatively they may supplement their diet by actively preying on insects, but this needs to be investigated.