Life History Evolution
Bats and Barometric Pressure
Studies were conducted to assess the response of a seasonal cave-dwelling bat and its insect prey to natural and experimental changes in barometric pressure. Experimental studies showed that the eastern pipistrelle tracks barometric pressure metabolically. In addition, eastern pipistrelles potentially use pressure as a cue for predicting the relative abundance of aerial insect prey from outside the roost while the bat is still roosting within the cave. Our results suggest that barometric pressure tracking affords these bats an opportunity to conserve limited energy and make appropriate foraging decisions. Barometric pressure tracking is viewed as an alternative evolutionary strategy to torpor and may be a widespread phenonmenon among insect-feeding bats that roost deep within caves.
Future studies should include the mechanisms involved in barometric pressure tracking. We know that bats are the only mammals in which the middle ear is not fully encased with bone, having a membraneous underside. Bats are also the only mammals with a Vitali or paratympanic organ in the middle ear (located above the membraneous portion of the middle ear). Although the function of the paratympanic organ has yet to be demonstrated conclusively, measurement of air pressure seems the most likely function.