You may recall that I was fascinated last year by the Daubenton’s bats hunting over a pool on the River Alyn, which runs into the Dee not far from Wrexham. After trying to photograph them by hand, I started a project to photograph them using a laser beam and electronic flash.

I thought that the bats were flying in and out of the mill race in the above photograph, so, having perfected my equipment over winter, I set up a laser beam across the gap. Guess what? The bats zoomed around the pool, went past the mill race opening many times, but did not enter the opening and break the beam once! Either they have changed their behaviour, or I was wrong – easy to do, maybe, as the bats did not appear until it was quite dark.

However, the flash went off several times. When I went through the pictures – there were a lot, as the camera lens is open all the time, just closing momentarily in order to avoid problems associated with long exposure times – I found that among them was this one, with a red dot in it.

Enlarging the red dot tremendously, I have this:

This is the midge that set off the flash by interrupting the laser beam, photographed from about 4 metres away with a Canon 500mm f4, proving that my focus was pretty good – note the wings and flash-illuminated legs.

So no bats, but an indication that success was possible if the laser beam was where the bats were flying!

Movie clip from a camera trap, showing a grey heron investigating a tree which has fallen in the river.

We walked down to the river in the dark, and I stood beside the pool where the river widened after rushing under the bridge, waiting for my night vision to kick in. After a while, the presence of bats made itself felt – flicks of black against light parts of my field of vision, occasionally resolving into movement of small objects for a short distance before disappearing into the darkness again.

Bill set up the torch with its powerful beam crossing the water from the bank on which we stood  to the channel emerging from the sluice gate. We waited for a while, then suddenly a pair of bats appeared out of the blackness above the pool and flashed in and out of the light beam.

I set up my camera and flash gun and waited for them to appear again. After a few minutes, a bat appeared and I took a shot at it. Checked the camera – no bat. However, they continued to appear, usually in pairs, zoming around the pool at a height of one or two feet, looking a bit like fighter planes, leader and wingman. I continued shooting, and eventually starting getting photographs with bats in – sometimes parts of bats at the edge of the photo, but quite a few reasonably central.

The bats kept coming for a long time, although I didn’t notice the time going by as I was enjoying myself so much. This kind of photography appeals to the hunter in me, although by the end, I felt like a hunter who had not brought home much for the family meal. The best of the photographs were mostly out of focus, and those that were in focus suffered from movement blur.

However, I noticed that the bats frequently flew in and out of an opening (see the photograph at the top of the page) leading to a sluice gate, and I had an idea for getting some decent photographs. A flashgun which was triggered when a bat interrupted an infrared beam across the opening would probably be fast enough to produce a photograph in focus.

Stopping the motion blur will involve firing a flashgun at low power, which means that it will need to be closer to the bat.

And the camera’s shutter will need to be open when the bat interrupts the beam.

Hmm …