Listening for Noctule Calls
These bats are big and fly fast but the repetition rate of the calls is slow, on average about 4-5 pulses per second, but sometimes even less as they fly high above the trees.
Play the sound at the top to hear a noctule heard through a heterodyne detector tuned to 25kHz.
The bat is flying high with its typical loud two part call - high and then low.
The ‘chop’ part of the call is the deeper and longer of the two sounds and is easier to tune into to find the peak frequency. If you find that the deepest frequency is at 21kHz or below you can be fairly sure this is a noctule bat.
Identifying Typical Noctule Calls:
• Call often has two parts and sounds like ‘chip-chop’ (but not always alternating).
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