Bat School · Free & open to everyone
Which bat is that?
A visual guide to European bats, told through their calls. Pick your country, then compare frequency, the distance between calls and call shape — with a real-looking spectrogram for every species.
biosonic.io/bat-school — bookmark it; updated as the guide grows.
Find it by frequency
The frequency ruler
Heard a peak frequency on your detector? Find the candidates here. Each bar spans the call's range; the dot marks the peak (loudest) frequency — the most reliable single number. Sorted low → high.
Find it by sound
The five sound types
Almost every call is one of these five. In each tile: height = frequency, left→right = time (0–500 ms), the gap between marks = the distance between calls, and the bright part shows where the call's energy peaks.
Family by family
Every species
Grouped by genus. Each card shows the example spectrogram, the key numbers, and the one tell that splits it from its look-alikes.
Frequencies are in kHz, shown where the call's energy peaks (the loud, flat part — not the faint top of the FM sweep). “Distance between calls” and duration are typical search-flight values in milliseconds; both change a lot with what the bat is doing (commuting vs hunting vs the feeding buzz). Reference values are midpoints cross-checked across the Bat Conservation Trust guidance, Russ (2021), Barataud (2015), Middleton (2014), Skiba, batmonitoring.org and national sources (SE/DK/NL/DE).
Hear these calls on your own recordings
Upload your WAV files and BioSonic shows the spectrogram, the species and the call statistics — so you can check every ID against this guide.
The expert's checklist
How an expert reads a tricky call
Acoustic ID alone isn't always enough — weigh these together, and always read the habitat.
Call shape tells you what the bat is doing
| Type | Shape | Used for |
|---|---|---|
| CF | Flat horizontal line | Orientation (horseshoe bats) |
| QCF | Hockey-stick (hook right) | Cruising / navigation |
| FM | Steep vertical line | Precise targeting when hunting |
Feeding buzz: calls turn vertical and pack tight — like a ping-pong ball bouncing to a stop — then return to the hockey-stick once the insect is caught.
Three classic look-alike pairs
The 30-second route
Quick decision tree
A fast first pass to the right family. It won't settle every Myotis — but it gets you close in seconds.
Listen & learn more
Hear real calls & go deeper
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Photo credits