My New Bat Detector

[scipio]

There seems to be a dearth of bat detectors in stock in internet stores and I count myself lucky to have received mine before they all hibernate (the bats that is!). I am now the proud owner of a Ciel 101.
We are amazed at the huge amount of ultrasonic activity in the garden. We find no difficulty identifying both species of Pipistrelle (they fly around the bottom of the garden at dusk but seem to get closer to the house around 22:00).
Much, much louder is the very regular "chop" (just above one per second) of a much chunkier bat that hunts parallel with the line of houses. Its peak volume is at 22.5Khz but I can also pick up fainter warbles at 39khz (possibly harmonics, as they only occur when I hear the 22.5khz calls?) The bat appears to sweep across many gardens and then turn and retrace its steps. Because it is so loud it can be heard coming from some distance. I thought it might be a Noctule but I do not hear the chip/chop (just the chip bit- an FM sweep). I have listened to the recordings of Noctule, Serotine and Leislers on Brigg's and King's Bat Detective CD and while it has similarities with all of them it isn't exactly like any of them. I would be happy to receive any suggestions on how I might go about deciding which species it actually is, or indeed what you hunches might be.

We also seem to have a relatively static source of ultrasonic calls (36khz) on/in our shrubs and hedges. These insects(?) also chirp at about once per second and can be tracked to an individual branch. When I twist the branch look with a torch the noise stops. can't see the source though. Many of you with bat detectors will have heard this as well. Any ideas on what it is.
Thanks for any advice.

[thunder]

I'd guess that your bats are either Noctules or Leisler's. I'd tend towards Leisler's as they certainly produce more chips that chops.

The insects in the bushes are almost certainly Dark Bush Crickets (Pholidoptera griseoaptera). THey can be a real pain on a warm damp evening!

henrya

[nightshade]

I agree with Henrya,except that the Serotine can cause a similar sound
Have you tried looking high in the sky (where the swallows and swifts fly)
I have a Noctule that turns up around 19:45 hrs. long narrow wings fast
flies high Serotine a little smaller chunkier but similar flight
If I cannot pin a call down I ring around my Bat Group or go to Warwickshire Bat Group to check
You do seem to have the technique off pat though just remember
a change in terrain will alter a call eg open parkland tall trees

[scipio]

Thank you both for your thoughts. While I have tried understand the technique (I have avidly read the books) I have absolutely no practical experience (apart from a couple of bat walks:-Pipistrelle in Ireland and Daubentons in Winchester). That is where the frustration comes in.
This bat ticks some boxes of one variety and some boxes of another. e.g 22Khz and even pulses= Noctule, whereas chip and no chop and flying at lower levels= serotine or leistlers.
It certainly doesn't fly as high as swifts. We are in a wooded area and it flies below the tree tops and often below or at the eaves. If I point the detector out of a bedroom window I swear I can hear its wings flapping (through the headphones) when it gets close. It (if its the same one) seems to appear as early as 19:30.
I guess I must go on more bat walks with the experts

[thunder]

Originally Posted by scipio

I have avidly read the books

But I bet the bats haven't!

henrya

[nightshade]

I had the Noctule up and a Serotine, one comes over as "chonk" (noctule 20-25mHz)
and the Serotine as "tock" 25-30mHz (nearest Leislers a roost in Bristol)
So it depends I suppose is it flying towards you or away which part of the call is
picked up it certainly takes practice

[scipio]

Nightshade,
Thanks again for the advice.
I would describe my bat sound as a "squelch" (which I guess is closer to a "chonk" than a "tock"), but I suppose this must depend to some extent on the technical characteristics of the bat detector (the filtering applied, the headphones used and the difference between the set frequency and the bat's call).
Although it was very dark I think I got quite close to it last night. After the "squelch" I could hear a much fainter sound that I can only describe as wet warble (like fast liking-of-lips). It may be the same sound as the "wing flapping" I described in an earlier post.
Have you heard anything like it. It is much, much quieter than the main pulse.
Overall, I still can't decide whether we have a Noctule or a Serotine but I think the sight of me wandering around in the dark is beginning to worry the neighbours if not the bats!

[thunder]

Originally Posted by scipio

Although it was very dark I think I got quite close to it last night. After the "squelch" I could hear a much fainter sound that I can only describe as wet warble (like fast liking-of-lips). It may be the same sound as the "wing flapping" I described in an earlier post.
Have you heard anything like it. It is much, much quieter than the main pulse.

That description sounds to me like the sort of noise you get when there is a Pipistrelle or Myotis either going past at extreme range or if you have the detector tuned well away from 45.

Keep on listening - it's the only way, and as you say each detector has it's own special characteristics

henrya

[nightshade]

Somewhere on the site are a Bat Frequency chart and a flight characteristics chart
these may help if you can find them
Something that occurs to me you are not picking up a blackbirds alarm call this can vary in sound as you change frequencies 'specially in the lower twenties (just a thought)
Henrya is also spot on with his observation,keep practicing go out with a bat group to
areas where particular species are to be found bats just do not play fair