Bats in the Copse

Holt Copse and neighbouring Joel Park are home to both Pipistrelle and Noctule bats. Several old oak trees show the tell-tale signs of habitation by Noctule bat colonies (A black streak of urine and faeces trickling from the roost hole). It has been observed that the Noctules change their roost sites around the Copse regularly, and may only use a particular roost for a couple of weeks during the summer before moving on.

The Noctule bats can be observed emerging from these roosts during the summer months at dusk, just before it gets dark. They fly high and head straight for their feeding grounds, which may be several miles away from their roost site. The Pipistrelles, on the other hand, are best observed hunting prey in the newly coppiced clearings in the copse.

The HCCV own a couple of electronic bat detector boxes which can be used to detect the ultrasound "radar" emitted by the bats when locating prey. The Noctules are best heard with the detector set to 25kHz, while the Pipistrelles can be heard at approximately 50kHz.

Here are some examples of what you can expect to hear when using the bat detectors:
(Click the link to download and play the wav audio file)

Pipistrelle (49kb)
Pipistrelles usually sound like irregular "smacks" that tend to vary in the pitch and are at a medium
repetition rate.

Noctule (59kb)
For Noctules the sounds from the bat detector are usually alternate "smacks" and "tocks" at a fairly slow repetition rate which together sounds like a fairly irregular "chip-chop". The ‘chop’ sound is produced at less than 22 kHz, and there are slightly more ‘chips’ produced than ‘chops’

During the summer of 2001 the HCCV conducted some basic counts of Noctule bats emerging in Joel Park.
Here are the figures:

Check out the Bat Conservation Trust at http://www.bats.org.uk/ for more useful bat related info.

Holt Copse Conservation Volunteers

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