Clicks, pops and raspberries!
Judi Darley reports on a nocturnal sortie
Nearly 40 people turned out on a lovely evening on August 9 to listen for bats and look for moths in Brandy Hole Copse. Our leaders were Peter Etheridge and Mike Perry from the local Natural History Society.
Being such a lovely clear evening it took a while to get dark enough for bats to begin flying and so Peter entertained us with interesting and amusing stories about our local wildlife. We began our walk by listening out on the bat detectors for the “click” noises emitted by crickets. These detectors are little portable black boxes with listening devices that are designed to pick up the very high pitched noises emitted by bats using echo location to search and find their food. The boxes change the sound down into a frequency heard by us, usually in the form of clicks, pops and even raspberries!
We learnt that the raspberry noise is made as the bat closes in on its prey to eat it. We heard the “wet slap” popping sound of the country’s smallest bat the pipistrelle and the drier sound of perhaps a serotine. We learnt that the bat is our best friend as it can eat up to 3,000 insects such as mosquitoes every night.
During the walk we heard reports that bats were busy near the moth trap set up in the woods for the evening and made our way to see what was going on there.
The trap had been set up by Mike Perry and friends by the big oak tree at the top of the main ride. It was easy to find by its very bright light, which we learnt was at least four times brighter than our 100w bulbs at home. The moths were attracted to the bulb and then settled on a cloth placed around it or in special collecting chambers nearby. Each moth was collected in a bug pot, identified and recorded and then put in a special chamber to be released at the end of the recording session. We learnt that this was to avoid recording the same moth more than once. Usual woodland species were found including the maiden’s blush, oak hook-tip and the rosy footman.
We did make note that during this time the occasional bat was detected flying overhead and the raspberry noises emitted indicated that some moths never did make it to the trap for their moment of glory.
We had an enjoyable and informative evening and thanks to Peter and Mike and their Natural History colleagues for giving their time to lead us on this event.
