Une présentation atypique de purpura fulminans méningococcique : à propos d’un cas observé au Niger chez une fillette de 5 ans

In Southeast Asia, wrinkle-lipped bats (Chaerephon plicatus) roost in colonies that may count several million individuals. Birds of prey frequently hunt these bats when they emerge from or return to their colonies. Here, we report on an extreme anti-predator behavior of this species during return flights at dawn. Based on data logger, we documented that bats may ascend to several hundred meters altitude above the cave shortly before diving at high speed (maximum 20 m/s) towards the entrance. Dive rates were 40 times higher than those reported for other open-space foraging bats performing flapping descending flights. Based on high speed video recordings, we show that C. plicatus brake the rapid descents close to the cave entrance using the tail wing membrane and partly extended wings. Maximum gravitational forces involved 2.4 G, probably when adjusting abruptly the speed close to ground. We argue that these descending maneuvers may constitute an anti-predator strategy of C. plicatus, since such descents may be too fast and complex for birds of prey at the cave entrance, particularly when performed by thousands of individuals at the same time.