Eptesicus The Big Brown Bats

It has been known for many years that bats use echolocation to navigate and find prey in the dark. What has been left unanswered is how that when bats are flying together are not found running into each other due to interference of sound waves from their neighbours. It is known that bats do not have any problems with this interference because bats have been observed flying in swarms and capturing prey with not a problem. What scientists are now trying to discover is how the bats can get around the problem of interference. It has been hypothesized that the bats change the frequencies in response to other signals to avoid interference or “jamming”. Most previous research that had been done was basic observation of bats flying together. It …show more content…
The researchers selected three of these bug brown bats to be used in the experiment. They preferred this species of bat because they are capable of discharging frequency-modulated (FM) bisonar, which covers a wide range of ultrasonic frequencies, but also a narrow band that is utilized for longer distance target detection. The researchers tested trained bats when a constant frequency jamming tone was present and when it was not. This was to simulate the jamming frequencies that may be present in free flying …show more content…
However when two bats of the same species were observed flying together, the bats discharging the higher frequency would increase their subsequent frequency. The bats releasing the lower frequency would lower their frequency in response to detecting the higher frequency of the other bat. It was also seen in other species of bats that there is a JAR response. In this case the higher frequency bats increased their frequency upon detecting signals from the same species of bats. The lower frequency bats instead of lowering their frequency instead just remained at a constant frequency. These responses however were only short term. It was also discovered in previous research that bats utilizing CF signals are more vulnerable to CF jamming signals than those that do not. Schmidt and Joermann propose that this result might be due to the fact that the CF signals lack the bandwidth of the FM signal that might help the bat classify their own calls from those of others. It was discovered in this experiment that each of the three big brown bats that were tested had different frequencies in which they shifted their response, though the mechanism of the response pattern was the same. These results were found to be consistent in other species of bats as well. It was hypothesized by previous researchers