Research results published by the Royal Scientific Society of London have shown that gray-headed moth bats use an unusually wide range of ultrasonic signals to navigate in the dark, from shrill screams to low whispers.
To learn more about the features of this biosonar, the researchers installed infrared cameras and ultrasonic microphones to record the voices of bats flying over the California coast in the fall.
Sound research continued for five nights. In about half of the 80 flights, they were shorter, faster, and quieter than the voices of other bat species. Usually, as the mice get closer to the object, the intensity of the signals increases, but here, literally halfway to the obstacle, the gray-headed bat did not make any sounds at all.
This hidden flight mode explains a lot - in particular, the rather numerous collisions of mice with wind turbines. Moreover, the sounds are so quiet that they sharply reduce (by about 3 times) the ability of bats to detect obstacles.
A legitimate question arises: What is this "conspiracy" for? Scientists suggest that by doing so, animals avoid unnecessary encounters with aggressive relatives during the mating season. At the same time, the ability to hear the opponent is reduced from 92 to 12 meters. Apparently, we are talking about a kind of behavior tactics of rival males.