A note on the thermal ecology and foraging behaviour of the Egyptian fruit bat, Rousettus aegyptiacus , at Mt. Elgon, Kenya

The Egyptian fruit bat, Rousettus aegyptiacus, is an abundant and widely distributed African pteropid (Nowak, 1999). The species is unusual amongst pteropids in being an obligate cave-dweller (Kwiecinski & Griths, 1999), sometimes reaching colony sizes in the thousands (Kingdon, 1974). In the caves of Mt. Elgon National Park, western Kenya (1 08¢N, 34 39¢E), precision temperature loggers placed in major Rousettus roosts and intervening passages have allowed us to precisely monitor bat emergence and return times. The major caves of Mt. Elgon National Park consist of geophagically modified tunnels and collapse chambers cut into Miocene-aged pyroclastic strata (Lundberg & McFarlane, 2006). These caves can be as much as 200-m deep (e.g. Kitum Cave) and can have volumes exceeding 4 · 10 m (e.g. Makingeny Cave). The caves support at least 11 species of bats (Bauer, Weis-Spitzenberger & Weis, 1981). The caves are of interest in the present context because, being located at relatively high altitudes ( 2500 m), the ambient rock temperatures are low and the large biomass of bats produces significant temporal fluctuations that more than doubles roost temperature.