A new study published in the Biology Letters, by researcher Christian Voigt from the Leibniz Institute for Zoo and Wildlife Research in Germany talks in detail about how and why wet bats face major flight trouble and vision imparity.
Similar to insects and birds, bats have evolved a powered flight. Though, the flight becomes impaired in case of rains, when bat pelage and wing membranes get wet. Short flights were studied by scientists in Carollia sowelli (bat specie) that was exposed to heavy and frequent rainfall in neotropical rainforests. These bats encountered higher thermoregulatory costs and suffered from lowered aerodynamic properties when pelage and wing membranes caught moisture.
Flight metabolism was quantified in three treatments: dry bats, wet bats and no rain, wet bats and rain. Dry bats showed metabolic rates predicted by allometry (growth of body parts at different rates, resulting in a change of body proportions). The researchers found that dry bats expended 10 times more energy than while at rest, but wet bats expended 20 times more energy.
Here’s what explains the above analysis. Just like in humans, rain may have the same cooling effect to the bats causing them to increase their metabolism rates in order to stay warm. The other possible explanation is that, rain causes the bat’s fur to clump together which may leave the bat less aerodynamic in flight, causing the increase in metabolic rate.
This therefore helped in concluding that bats avoid rain not only because of sensory constraints imposed by raindrops on echolocation, but also because of energy constraints.
Further research is necessary to determine if these explanations are correct or not, but one thing is clear, with the rain situation going batty every year in India, it's no surprise why bats hate the monsoons so much!
Photo by Susannaduffy.