Bats help against bad eyes and toothache, fever and hair loss. At least the ancient Egyptians were convinced of this. Hanging over the door, the animals should drive away the very demons that were supposedly responsible for such health problems. And these are far from the only abstruse stories that people have invented about the nocturnal hunters. In medieval Europe, for example, the fluttering animals were considered messengers of the devil and effective ingredients for all kinds of witch potions. But their real talents have long been underestimated. Because of their secretive lifestyle and poor reputation, they have tended to lead a shadowy existence in ecological research until recently. Instead of spending their nights on bats, scientists prefer to focus on animals that are easier to observe, such as birds or bees. "Only recently has there been a shift in perception", says Christian Voigt of the Leibniz Institute for Zoo and Wildlife Research (IZW) in Berlin. "It is now becoming increasingly clear that bats play an important role in many ecosystems."
Winged string pullers that can become active in the earth’s habitats are, after all, more than plentiful. After all, bats have conquered all continents except Antarctica and are the second largest mammal order with more than 1100 known species. Only rodents have managed to achieve an even greater diversity. In the tropics and subtropics in particular, numerous species flutter through the night, dedicated to a wide variety of lifestyles. Insect hunters are on the move there, as are vegetarians – and, cliche-like, a few vampires who feed on the blood of other animals. But they all influence the other plants and animals in their habitat in their own unique way. And humans can also benefit from this.
This article is included in Spektrum – Die Woche, 01/2016
Insectivores help control pests
"Insectivores, for example, very clearly decimate the populations of their prey.", says Christian Voigt. No wonder, given the huge swarms the nocturnal hunters congregate into in some regions. The Khao Chon Pran cave in Thailand, for example, is home to some 2.6 million free-tailed bats of the species Tadarida plicata. "When they fly out in the evening, it’s a very impressive spectacle", the IZW researcher knows from his own experience. For more than an hour, a huge band of fluttering animals then streams out of the cave. And each of them can eat its own body weight of 12 to 15 grams of prey in one night. In the vicinity of this cave alone, 17.5 tons of insects are collected per night. For Thailand as a whole, this amounts to 20,000 tons per year. A related species in North America, the Mexican bulldog bat, has a similar penchant for mass gatherings (Tadarida brasiliensis). An estimated hundred million of these animals live in caves in northern Mexico and southern USA. Their prodigious appetites prey on more than just insects in their immediate vicinity. Since they can climb to an altitude of 3,000 meters and cover more than 100 kilometers in one night, they can also catch swarms of insects that migrate over long distances.
