The ability to know by air pressure that meals are available probably also helps the small flying mammals conserve energy, he said. Barometric pressure is the only physical environmental cue available to a bat roosting deep within a cave. All other variables such as light, temperature, relative humidity and wind currents are virtually constant. When air pressure is low, aerial insects are abundant, and bats respond by leaving the roost to forage. Paige's research was published in the June issue of the British journal Functional Ecology.
Bats are the only mammals to have such a sensory organ.
Watching bats at a cave near Pittsfield, Ill., during late summer, early autumn and early spring, Paige studied the relationship between bat and insect activity and barometric pressure. He found that the bats emerged in larger numbers when insects were numerous. He noted that the number of insects declined dramatically and that fewer bats left their roost when air pressure had risen. Paige also showed that bats track barometric pressure metabolically. When the barometer falls, bats slow down their metabolism, allowing them to conserve energy.