spectrum diagrams

During a visit to Germany Tony Messina spent some evenings at locations in and around Kiel for recording european bat calls with his Anabat system. Here are just a few of his recordings, showing only species which we could identify with the help of visual observation and comparison in a heterodyning receiver.

The graphs are frequency-time diagrams. You can read the frequency in kHz on the vertical axis and the time on the horizontal axis. The pauses between the calls have been removed so that more calls can be displayed in a single graph.

Nyctalus noctula

Nyctalus noctula hunting in free airspace. This bat uses two alternating calls, which is clearly visible at the beginning and at the end of this sequence. Especially the part of the call between 18 und 20 kHz can be heard over quite a distance (+ 60m ?). The time between calls is about 150ms (not visible in the graph because of compression).

Eptesicus serotinus – Breitflügelfledermaus

In a heterodyning receiver these calls sound like those of the Nyctalus noctula, but there is just a single calling type, which is also a little higher in frequency. Unfortunately this is only a short sequence, but most of the time we had some Pipistrellus pipistrellus hunting in the foreground.

Pipistrellus pipistrellus – Zwergfledermaus

This is a nice, long sequence of echolocation calls of one of our smallest bats. The loudest part of the call can be heard around 44 kHz.

Pipistrellus pygmaeus – Mückenfledermaus

Recently discovered, the calls of the even smaller Pipistrellus pygmaeus look like those of the Pipistrellus pipistrellus, but the spectral display shows clearly, that it is calling 10 kHz higher.

Pipistrellus nathusii – Rauhhautfledermaus

In a heterodyning receiver the Pipistrellus nathusii sounds like the Pipistrellus pipistrellus, but the spectrum clearly shows that the calls are a little bit longer (probably very hard to notice) and on lower frequencies.

Myotis daubentonii – Wasserfledermaus

These are probably the calls of a Myotis daubentonii, but in that area also Myotis dasycneme can be found, so it is better to say „myotis calls“ to this spectrum. Compared to all the other calls on this page, these calls are very steep and in a heterodyning receiver they just sound like „clicks“.

Soziallaute Zwergfledermaus

These are social calls coming from a bat box, which is normally occupied by Pipistrellus pipistrellus. Since the recording time was late August, these calls may be mating calls. Unfortunately the box was destroyed in summer 2009, we hope that the bats will accept a replacement box at the same site.

Die Kommentarfunktion ist geschlossen.