Thursday, 23 June 2011

Batman and Dobbin

Glastonbury Festival time again, you can always tell when the festival is due to start. The clouds roll in and the rain tips down.

I took the dogs out for a walk last night a bit later than I usually do. I took with me my trusty bat detector to see what nocturnal wildlife was around. There are 18 species of bat in the UK (17 of which are known to be breeding here). I have so far over the last two years detected six different species.

All bat species are diminishing in numbers, possibly due to their diet of insects reducing because of pesticides and habitat loss. Bats hibernate in winter when their food source is at its most scarce. Bats are protected under the Wildlife and Countryside Act 1981, The Habitats Regulations 1994 and the Countryside & Rights of Way Act 2000.

We have a large farm field hedgerow in the back garden. There are several horses in the field beyond and it seems that Dobbin's poo must be good for attracting insects. The bat detector picked up a few Daubentons bats. Daubenton's tend to frequent all kinds of waterways as their preferred habitat. There is a large lake about 150 yards away behind the house. So I assume that its the lake that attracts them into the area and our back garden is on their flight path to the lake.  Daubentons are known as the "water bat" as they fly low over the water, fishing for emerging insects on the water surface.

Daubenton's Sound.
Daubenton's Factsheet.

I also detected a few Common Pipistrelle bats hunting along the hedgerow. Pipistrelles are the commonest British bat. A single Pipistrelle can eat several thousand tiny insects in just one night! When I reached the field where I let the dogs run free. I detected another Pipistrelle which went on to do a master class in hunting down insects. There was just enough light to be able to see the silhouette of the bats and the larger insect prey. It seemed that the bat at times would only be able to catch an insect after many attempts, but they are persistent little furry beasts!

The moths had a curious tight spiralling downwards flight whenever they detected the ultrasound of the bats. The bats were not agile enough to spiral as fast or to turn in as tight a circle as the moths. The Pipistrelle bats seemed unable to detect the moths once they were very close to the ground.

Pipistrelle Sound.
Pipistrelle Factsheet.

Later, I detected what I think is a Barbastelle bat, the habitat, flight pattern, size, sound and the frequency 37khz seem to fit this little flying mammal's modus operandi. I will get Dr Steph to bring her professional bat detector on her next visit. A sonogram is the only way to confirm if Barbastelle are in the vicinity. There are nine known species recorded by the bat group in my area and the Barbastelle is not one of them.

Barbastelle Sound.
Barbastelle Factsheet.

From time to time I could detect a fourth kind of bat, but one whose sound I had never detected before. At the time I had no idea which kind of bat it was. After about half an hour messing around in the dark during a heavy rain shower trying to catch a glimpse of the elusive bat. The penny dropped and I suddenly figured out which kind of bat it was. It turned out to be a very rare WHFT bat.

Chameleon ELF tm-1
Our two Wire Haired Fox Terriers have just been fitted with new metallic name tags in addition to their metallic "chip ID" tags. The ultra sound of the tags jiggling together are not audible to us humans. The bat detector picks them up without a problem. The standard test of a bat detector in the absence of bats is to jiggle a set of keys, I should have known better.
Magenta Bat5
Two soggy doggies and one soggy bloke arrived home feeling a bit of a twerp!

I use a Magenta Bat5 digital hetrodyne detector, which is a mid range device. I am looking forward to being able to do some bat observations. Using the detector and a Chameleon ELF tm-1 night vision monocular when we are out on the boat later in the summer.


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