Driven up the pole by bats

The bat group has recently bought another Griffin from Batbox using the proceeds from data searches. The fine weather on Monday night was too good not to exploit and Bob headed off to the home of our main bat box project to try it out.

We noticed that last season that bat detectors placed at 8.5 m ( atop a window cleaners pole and a de-bristled brush) gave us very different results from what we heard at ground level, but as we only had one Griffin we could not record at two levels at the same time with a time expansion detector)( We used . batbox Duets instead which , not being time expansion detectors, can’t give such high definition recordings)

The first Griffin was mounted on the lower part of the window cleaner’s pole. Photo Bob Cornes

Using a Petterson time expansion detector which was handheld, Bob only reported a few common pips, , the Griffin placed on the pole low down picked up a Noctule pass, while the Griffin at canopy height picked up both common and soprano pips, a serotine, a barbastelle, and what was possibly a Leisler’s (though it might just have been a Noctule playing silly devils.

The double Griffin se4t up. You can just about see the 2nd Griffin at canopy height right at the top of the photo. The object ion the tree trunk is a bat box (unoccupied) Photo Bob Cornes

The plan is to repeat this methodology at a number of sites this season, and to return here later in the yer when the canopy is denser.

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