Surveying Great Crested Newts underground

[Deb London]

I received the following in a series of emails concerning GCNs and how best to serve their interests.

"I'd like to be able to insert an endoscope device to see inside the hibernaculum - but without illegally disturbing the GCNs within. I don't know whether this has ever been done before."

Has anyone ever had experience of this type of survey? Ours would be done by license holders from the London Essex & Herts Amphibian & Reptile Trust. But is it a worthwhile project to pursue?

[Dogghound]

I have used one for bats which does not cause much disturbance. For GCN if its being carried out by a license holder it will be fine in a legal sense. Although it is important not to damage the structure, physically touch or disturb the newts. A better way of monitoring hibernacula use is by placing newt fencing around them in the spring and collect anything coming out of them on their breeding migration. However it must first be decided if it is in the interest of the amphibians to carry out any disturbance, is it for scientific study, or to just see whats there? If you already know GCN are in the area then is the disturbance worth it? these are the things you need to consider. Observation of GCN within an area is far better when they are breeding, going to the pond after dark with a tourch will reveal a lot more than if they are hibernating. Unless you are testing the use of a structure.

[mammalrecorder]

Hi Deb

I would check with Natural England first. The standard endorsements on GCN licenses cover refugia searching BUT this is not the same thing as hiburnacula searching. It would be very difficult to insert an endoscope into a hiburnaculum without causing disturbance and of course that would almost certainly result in death. I suspect that NE would want to see a clear research plan and evidence of competence etc before giving a decision.
I have GCN licenses for England Wales and Scotland and none of them would license me to insert anything into a hiburnaculum.

[Dogghound]

Of course sorry, yes as mammalrecorder says any work, or proposed work needs to go through Natural England first.

[Deb London]

Thanks both. I believe the idea is to test the use of a structure.

Originally Posted by mammalrecorder

Hi Deb

I would check with Natural England first. The standard endorsements on GCN licenses cover refugia searching BUT this is not the same thing as hiburnacula searching. It would be very difficult to insert an endoscope into a hiburnaculum without causing disturbance and of course that would almost certainly result in death. I suspect that NE would want to see a clear research plan and evidence of competence etc before giving a decision.
I have GCN licenses for England Wales and Scotland and none of them would license me to insert anything into a hiburnaculum.

To be honest, I really do not like the sound of what could happen, even though I'm confident that every effort would be made to avoid any disturbance whatsoever.

[Deb London]

Originally Posted by Dogghound

I have used one for bats which does not cause much disturbance. For GCN if its being carried out by a license holder it will be fine in a legal sense. Although it is important not to damage the structure, physically touch or disturb the newts. A better way of monitoring hibernacula use is by placing newt fencing around them in the spring and collect anything coming out of them on their breeding migration. However it must first be decided if it is in the interest of the amphibians to carry out any disturbance, is it for scientific study, or to just see whats there? If you already know GCN are in the area then is the disturbance worth it? these are the things you need to consider. Observation of GCN within an area is far better when they are breeding, going to the pond after dark with a tourch will reveal a lot more than if they are hibernating. Unless you are testing the use of a structure.

Thanks.

I will pass this suggestion on to those concerned. Although I wouldn't have thought anything was worth trapping them for really, in this case. This is my opinion, being generally very opposed to trapping creatures that aren't pests, unless absolutely necessary and unless it is in their interests. If the idea is to see if they are using the structures that we have already built for them, then I think we might have reached a dead end. Unless there is a cleverer, not invasive and most definitely non-fatal method.

WRT the endoscope, I have in my possession the new newt refuge design. This would certainly allow for the use of an endoscope without disturbance. But it's quietly dawning on me that no structure has ever been built for amphibia/reptiles to this specification, and that there might be a number of very good reasons for this. No doubt I will post the design soon for comment. I suspect that one of its drawbacks is its light and airy interior. It sounds like they like things a little more complicated.

[Mark_b]

Endoscoping the hibernaculum seems unnessasary, I wouldn't bother with it.

In terms of habitat pile / hibernation site creation, simply is the way to go.

[Matt Smith]

Originally Posted by Deb London

I received the following in a series of emails concerning GCNs and how best to serve their interests.

"I'd like to be able to insert an endoscope device to see inside the hibernaculum - but without illegally disturbing the GCNs within. I don't know whether this has ever been done before."

Has anyone ever had experience of this type of survey? Ours would be done by license holders from the London Essex & Herts Amphibian & Reptile Trust. But is it a worthwhile project to pursue?

Originally Posted by Deb London

WRT the endoscope, I have in my possession the new newt refuge design. This would certainly allow for the use of an endoscope without disturbance. But it's quietly dawning on me that no structure has ever been built for amphibia/reptiles to this specification, and that there might be a number of very good reasons for this. No doubt I will post the design soon for comment. I suspect that one of its drawbacks is its light and airy interior. It sounds like they like things a little more complicated.

I have a GCN survey licence and an endoscope, but have never used them together. What I have done is open up and remove an artificial hibernacularia (under licence in autumn) as it has been installed by the builders in the wrong place. I have also done a series of distructive searches for GCN under things like patios and concrete terraces.

The hibernacularia was the "typical" hibernacularia one sees in illustrations such as in the GCN Mitigation Guidelines, a pile of bricks covered with a permeable membrane and with soil and turf on top. We did find a few GCN in there, along with a couple a couple of frogs and toads. What was very noticeable was that the GCN were only found right at the very bottom of the pile of bricks where the bricks are in contact with the soil.

In my experience, GCN are very strongly thigmotactic, ie when seeking a place of refuge they seek out places they are very narrow and tight and where they are in contact with the substrate above and below them. As an example, here are a couple of pictures from the site:



This piece of 8ft x 4ft board is less then 10m from the hibrenacularia that had to be removed and resited. It had just been sitting on this fenced off section of path for a few months:



Here is the board lifted, if you look you can see 10 or so GCN sitting there - they have had to squeeze in under the board and they are not really in any cavities. On occasion I have lifted this board in summer and found over 100 (1 hundred) GCN under it, though that was the day I did not have my camera.

If you are planning to use an endoscope to look inside an occupied hibernacularia I think you will probably have great difficulty getting the endoscope down into the tiny spaces at the lowest levels to see if GCN are in there. I would be interested to see the design for your hibernacularia, I am fairly certain that a " light and airy interior" will have little attraction for GCN.

If I were to design a hibernacularia for GCN, it would be something along the lines of boards or tiles set into the soil with very narrow gaps between then so as to provide the small "crawl space" that GCN seem to favour.

Matt

Berkshire Amphibian & Reptile Group
Consultant Ecologist & Licenced GCN Surveyor

[Deb London]

Thanks you both very much.

Matt, Lovely pictures! Please can you give me your best guesstimate for the width of that crawl space in your hypothetical design? This is the sort of information we are lacking.

Thanks.

[Deb London]

Originally Posted by Matt Smith

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If you are planning to use an endoscope to look inside an occupied hibernacularia I think you will probably have great difficulty getting the endoscope down into the tiny spaces at the lowest levels to see if GCN are in there. I would be interested to see the design for your hibernacularia, I am fairly certain that a " light and airy interior" will have little attraction for GCN.

If I were to design a hibernacularia for GCN, it would be something along the lines of boards or tiles set into the soil with very narrow gaps between then so as to provide the small "crawl space" that GCN seem to favour.

Matt

Berkshire Amphibian & Reptile Group
Consultant Ecologist & Licenced GCN Surveyor

Well Matt, you did ask.

First the GCN dimensions calculations, in some detail:




Now for the ground level of the hibernaculum:



And some information about the background, the GCN domestic scenario (), some notes about the structure and its overall construction, and an appeal for ideas.

I found a photo of a GCN when turning a corner. this gave me an idea of how much space it needs to turn around inside the hibernaculum and go back or out the way it came in. I used information that Newts like to snuggle into tight-fitting niches and also that they like to walk along a fence "hugging" its surface until they reach a gap big enough for them to shelter in.

Then with the promise of lots more bricks, roof tiles etc, I designed a prototype hibernaculum.

Picture the following scenario...
A GCN reaches a rigid plastic edge, follows it, closely.
It leads to a group of bricks funnelled together with a terminal gap of 29 - 30 mm. So it squeezes through two of the bricks and enters into the dark interior of the hibernaculum. In the dark interior, the GCN can move forward or turn left or right and enter any "cell" of bricks in a concertina arrangement. It can snuggle between any two adjacent bricks angled against each other. At the far end of each cell a gap of 29-30 mm allows it to exit and find another such "cell" in which to rest. And when it wants to leave the hibernaculum, there is room for it to turn around and leave the way it came in - or go through another exit. I will have to modify the exits to enable a similar "funneling" effect.

Please note the following:
(1) The outer plastic guttering acts as a "wall" for newts to crawl against.
(2) Entrances made of cocertina'd bricks
(3) an interior of two rows of concertina'd bricks each pair of bricks being a "cell"
(4) the closest position of two angled bricks is 29 - 30 mm
(5) the turning distance is about 12 cm, but 15 cm would be better
(6) The sides would be of rubble - although if we have enough bricks, then they would suffice.
(7) We would need to design a ceiling.
This could be of roof tiles - if we have a sufficiently large number. I would suggest bubble wrap sheet put over the roof tiles. This plastic sheet would prevent earth falling through gaps. Also it would act as thermal insulation.
(8) To prevent burrowing predators - rats or foxes, we could put wire mesh on top of the plastic sheet.
(9) Finally a pile of clay and earth put on top. Ensure it connects with the ground outside the hibernaculum. We could plant a hawthorn or two ontop.

As you can see, the structure can be as long as you want it to be.
All entrances are inserted down one side as well as at each end.
There should be some ventilation - but no draughts.
The entire structure should be impervious to burrowing animals - foxes or rats.

I'd like your thoughts on this proposal.

I've definitely met my match here. I'm almost lost for words. Matt, Dogghound, MR, Mark, anybody?

PS I know I have another newt refuge thread, but that thread's a bit like wading through treacle. To make this post more relevant to the title, I should point out that this hibernaculum definitely has room for unobstructed 'probing' with an endoscope.

PPS I do realise that this design is complicated and rather detailed and ornate. But to be honest, we'd have it built in no time and I'm sure that would please the person/people who have designed it. But if the GCNs won't use it, what would be the point?