A personal selection of recordings of Swedish Bat Calls.
Most of them are made with the Pettersson D500X and all are showed using the program BatSound.
The recordings are made at 500 kHz, and that makes it possible to create detailed spectrograms.
For all species I will try to show a typical sequence of sonars, followed by some examples to illustrate the variation. The pictures mostly show a 2 sec sequence in the frequency area of 0-100 kHz. This is because it makes them easier to compare. You can listen to all of them, expanded ten times. That makes it possible to hear them and and sometimes that is a good way for identification. You can also download all original recordings through a link in the caption.
Recordings are often made by placing the D500 detektor in a tree and set up to start listening at dusk and being turnd of at dawn. It listens for ultrasound, and if it detects some, it starts recording for 4 seconds. Many recordings are made in Lillehem where the microphone is placed 5 to 6 meters up in a small tower, and the detector itself is indoors.
In the caption of most spectrograms:
- Original file name (To download: Right click, save link as…)
- Date, time, place with coordinates in Swedish Reference Frame, SWEREF99
- A Google Earth link for a quick flight to the recording place.
There is a chapter, Sound Analysis, which is thought to give a background on how bats are using their echolocation and why our recordings looks like they are. There are also some explanations on some terms used.
Regarding species identification, this is only one part of it. Often you need much more information to make a good identificatiion. Where does it fly? How does it fly? Sometims you really have to take a closer look at the bat, catch it carefully.
But sometimes you really can get much out of your recordings, and thet is what these chapters is about.
Two very useful books about bat calls:
Michel Barataud: Acoustic Ecology of European Bats