KORINE, C*; VATNICK, I; VAN TETS, I. G.; PINSHOW, B: Can Egyptian fruit bats (Rousettus aegyptiacus) alter their urine composition in response to environmental change?

We tested the hypothesis that the Egyptian fruit bats, Rousettus aegyptiacus under conditions of high-energy demands and high water intake save energy by increasing the proportion of ammonia in their urine. Eight bats were randomly assigned to one of four liquid sugar diets (219, 438, 658, and 877mmol sucrose L^-1), and exposed to one of two ambient temperatures (12&degC and 30&degC) in two different experiments. Bats were allowed four days to habituate to the cages and the liquid diet. After this period, we measured food intake for a further four days and on the fourth day we collected and analyzed the bats� urine. Food intake of bats acclimated to 12&degC was significantly higher than that of bats at 30&degC. Ammonia concentration in the urine increased significantly with food intake, water intake and protein intake at 12&degC but not at 30&degC. These results suggest that Egyptian fruit bats can save energy by altering their urine composition in response to environmental changes.