Bats skladchatogo Pallas distinguish relatives according to echolocation signals, which are used to search for prey. As noted in an article for the journal Behavioral Ecology, this ability allows you to stay within earshot with the other members of the group and together hunt in gregarious insects.
Echolocation is the main instrument through which insect-eating bats find food. In most cases, these animals emit ultrasonic signals are of two types: some serve to perform a preliminary scan of the area, and others help to precisely localize where there is prey. Their acoustic properties are unique for each species and depend on the area in which he hunts and what kind of prey he prefers.
For a long time, scientists assumed that echolocation signals are used only for hunting and orientation in space. However, as showed by recent studies, sometimes, clicks, localizing the victim, coded information for relatives — for example, sex, age or belonging to a certain group. Unfortunately, learning about communication of bats while hunting is not easy, so until now it was unclear whether scanning signals contain additional information.
A team of specialists led by jenna Wheels (Jenna Kohles E) from the Institute of animal behavior, max Planck Society decided to further explore the communication of skladchatogo Pallas (Molossus molossus). These bats from Central and South America live in groups of about ten individuals and mainly prey on small insects, which at dusk to form large clusters. To detect such a cluster is a difficult task, so skladchatogo from the same social group work together. If one individual finds the prey, the other dogs join her, focusing on the containment of ultrasonic clicks, and feeding together. This strategy allows just over an hour to meet the daily requirements in food.
To catch the signal fortunate kinsman, the members of one group of skladchatogo should remain within hearing, that is, at a distance of not more than 54 meters from each other. The researchers suggested that bats use the individual characteristics of the scanning sonar signals characteristic of individual animals.
To test their hypothesis, the authors caught 46 skladchatogo of the six colonies in Panama city and marked them with a small tag-transponders, and also recorded scanning signals used during foraging. After some time, the researchers re-caught 19 individuals from five groups and placed them in the cage for five to seven days. After that, they conducted experiments on the detection signals.
Each skladchatogo lost scanning signal of one congener from the group until then, until he ceased to respond. The scientists then reproduced the signal of another individual from the same group and checked the reaction of the tested bat. They suggested that if skladchatogo that has ceased to respond to the voice of the first congener to be responsive to the voice of the second, he feels the differences between them.
Analysis of the recordings showed that the scanning signals skladchatogo Pallas do differ from individual to individual. And behavioral experiments have confirmed the ability of individual bats to use these differences to distinguish between relatives. No signs of “group signature” indicate belonging to a particular skladchatogo colonies were found.
According to the authors, the use of individual characteristics allows hunting to skladchatogo to be close to relatives too far. No additional signals for this issue is not necessary. Although the need to maintain a scanning signal to the individual characteristics requires additional energy consumption and can reduce the effectiveness of echolocation, it kompensiruet the benefits of group hunting.
Many insects have learned to listen to bats, not to become their prey. For example, small crickets of the subfamily Trigonidiinaeliving in the rain forests of Central America, include a protective reaction in response to any ultrasound, reaching a certain volume. The presence of this threshold allows to ignore about the threat of the singing grasshoppers or votes of bats that are too far away.