RAUK - Archived Forum - Invert surveys before translocations

I've always thought of ground spiders/grasshoppers as suberb indicator for L.v and am sure you are right that they form a large part of their natural diet - an interesting point for consultants undertaking translocations where low numbers of animals already occur, do they check to see if this natural food supply is available in abundance?

Gemma Fairchild

Topic moved from 'Burrows Question'

Gemma,

I've never heard of a full invert survey being undertaken at a rep receptor site, I think standard practise is a 'visual assessment' or phase 1 habitat survey, followed by a reptile survey to check if there is an existing population. 

Some consultants think that existing population = suitable habitat, whilst others say existing population = too much competition.  I would agree that the presence of an existing population is a good indicator of a suitable receptor site (assuming that the receptor population is not genetically isoloted from the donor site) , but I don't think that there is any good guidance/research into how to assess a receptor site for it's carrying capacity.   Are there any reports out there that address this?

Jo

Jo, I've moved the topic to its own thread (rather badly hence my splicing of my original comment above yours )

I can see the dilemma of selecting a receptor site. On the one hand if no existing population, why not? On the other, if a population exists has it already reached carrying capacity? I can see arguments both ways and realise a low existing population may only reflect past management of the site, rather than a lack of natural prey items.

As an anecdote I tend see a lot of ground spiders on log and brash piles, perhaps no coincidence then that provision of logs and brash at receptor sites appears to be a key step in the successful translocation of viviparous lizards - perhaps providing a ready food source as well as cover. I would certainly be interested also if any studies have been carried out or if there is any way the subject can be looked into further to create some recommendations regarding invert populations/species required to increase the success of translocations.

It would be easy to establish presence of ground spiders at grassland receptor sites; they put abandoned tyres to good use as basking platforms in the same way that L.v do.

Clearly there is no need to carry out a full invertebrate survey for reptile translocations. You only really need to look at the abundance of prey species such as spiders, grass hoppers and other insects for lizards, molluscs and annelids for slow-worms, mammals and lizards for adders, amphibians and fish for grass snakes and so on.

You need to identify that the suitable prey species are present and ideally the site would not have a current resident population of the species which will be moved into the site.

A good rule of thumb is to make sure that the receptor site can be enhanced and is actually larger than the amount of reptile habitat which is lost - suitable habitat structure, prey items, shelter, cover etc. In situ solutions I have seen recently often lead to smaller areas of suitable reptile habitat being retained rather than using external receptor sites which can be much bigger than the original area of reptile habitat which is eventually lost.

You can assess prey items by using the same methods for reptiles - visual surveys and artificial refugia or cover objects - grasshoppers and spiders readily use these, rodents nest under them along with snails and slugs which live on the underside of these objects.

Recording the distribution and relative abundance of these animals would provide some idea of how suitable a site would be to move animals to.

A group of us consultants at the HWM - Gareth Matthes, Lee Brady, Barry Kemp, Myself and Natalie Walker had a small meeting and we are wanting to look at best practice guidelines for reptile survey, mitigation and monitoring.

We would like to get consultants to report their findings during surveys, subsequent capture results and monitoring survey results. We would like to look at the difference between sites across the country - looking at the type of habitat, natural areas etc and we would like to try and find figures to back up the reported densities of the different reptiles per hectare - for example the high end figure for slow-worms is reported to be 2,000 animals per hectare. We can look at that through the figures which have information on the size of habitat surveyed and captured from.

Consultants and the consultancy industry collect thousands and thousands of record each year. Herpetofauna records for example may be in the region of 500,000 records per year. Thats a lot of information which can be put to better use.

I am giving a paper at the November Conference for the IEEM - entitled Reptile Mitigation - Conservation or just killing them slowly?

I have prepared a questionnaire for consultants looking at different aspects of reptile mitigation work in the UK. I would like to get as many responses as possible so there is an incentive

I am going to provide a prize draw

top prize will be a hand held GPS plus other prizes all you have to do is fill in a form and send it back to me. PM me for further details and a form

Jon 

I think a problem with moving common lizards from one location to another that already has lizards is that you will be disturbing territories. More pressure = reduced fitness etc

In terms of all these records, do consultants submit there findings to their local biodiversity record office? If they donÆt then they bloody well should! That goes for all animals seen, not just reptiles!

Jon,

it may be worthwhile asking the contributors to this new collated data, when they survey, to keep an eye out for "level 2 barriers" which create filter routes, and "level 3 barriers" which create sweepstake routes.

It is the identification of these barriers which are crucial to any translocated populations survival, more than any given carrying capacity of an area and whether there are suitable prey items.

There should also be consideration to not only transporting the intended species, but also a number of suitable prey species also to kick start the settlement. While this might sound harsh, you would not dig a pond, furnish it with liilies, bankside vegetation and rockeries etc, buy some expensive Koi carp and then neglect to feed them would you?

It's time we thought of our native herps in terms of investement values as well as any other regard we hold them. think of them as you would Koi and then try to get that message across.

Cheers

Rob  

And in case you're wondering what level 2 & 3 barriesr may look like, here's an example with awrite up by yours truly.

And while we're talking about numbers, when you start talking 2000 individuals per hectare is just such an exagerated figure I cannot beleive that you could think there are anywhere near that number? As far as Grass Snake go, here are the latest recorded sightings with the biological records centre and to this, a friend of mine who's a computer whizz did a mock up using the trends to ascertain a 2012 map illustration of the way its going. it doesn't make happy reading for Grassie fans.

'2000 individuals per hectare is just such an exagerated figure I cannot beleive that you could think there are anywhere near that number'

Could easily apply for slow-worms and common lizards though is obviously way off the mark for any of the native snakes. This sort of data often comes from actual capture programmes so one assumes it was accurate. I've worked on sites where slow-worms were in excess of a 1000 per hectare so it doesn't seem exagerated.

Interesting whilst this debate rumbles on that I've never seen any evidence that prey items would be a limiting factor for a lizard species. The prey items are generally in huge abundance, there are other limiting factors as regards carrying capacity other than just food

Gemma,

I think that you're totally missing the point. If you say that nationally, there are about 1000 slow worms per hectare and the rea of the UK is 24.1 million hectares, you are implying that the slow worm population of the UK is 24 thousand million individuals!!!!!! Yeah right.

As 11 million hectares is given over to agricultural crops, and 4 million hectares is buried under tarmac then you need to qualify your figure with a BUT. Yes, there may be isolated instances where particularly favourable habitat might harbour that number of slow wrosm, but you cannot estimate a national population on that basis.

That would be like me saying that the same number of grass snakes live at Trafalgar Square as they do at Kent marshes, its total piffle!

 R

So, how many pockets in the UK are there???? Or to put it another way, how many optimum areas are there and how many hectares, in total, does that equate to?

And if "apparently suitable" areas turn out not to be optimum, how are you calculating the total number of optimum areas???

Ha-ha, get out of that one!

Within any professional survey I undertake I normally divide the site up in the most suitable habitats. i can then calculate the area of suitable reptile habitat within my site I can then extrapolate the density of sightings based on that area rather than the whole site.

Indeed the figure per hectare go much higher when using this technique.

reptiles are never evenly distributed across a site this is dictated largely by habitat condition, structure, disturbance and the time of year and day.

Here is an example of density figures of ACOs (I am going to use the term artifical refugia from now on) AR's from a survey site I managed this year

The Artificial refugia density is related to the suitable reptile habitat which was surveyed. In total 580 refugia were used and this amounted 167 per hectare. The same calculation can be made fromt he numbers of animals captured from each area.

On another site this year we have captured the following reptiles

SW   VL   GS

these are adult figures of what we have captured during a translocation from a site which is 10 hectares in total - clearly using the total area would provide the following density figures per hectare

Slowworms 91.3 Lizards 25.5 and grass snakes per hectare

We have divided up the site into smaller compartments of suitable habitats and so we will be totaling the capture rates per unit (Ha) of suitable reptile habitat we would have a higher density figure for different areas of the site.

Regards

Jon

We can only go on the published figures for density and the lowest is around 600 and the highest recorded so far is around 2,000 per hectare.

We obviously cannot use the total area of the UK to calculate the national population as the majority of the UK does no thave slowworms within it. We would need to calculate an estimate of the suitable habitat left even then the errors would be too great to be of any use.

J

Have a chat to Lee Brady he is devising a reptile habitat suitability index and we ar ealso looking at consultancy survey data alongside total capture data - this is the largest dataset we woul dhave on reptiles in the Uk which is largely untapped.

Lee has done similar studies with gcn, HSI and predicted population sizes of Gcn per natural area/geology in Kent. A similar approach would be needed for reptiles and it would be the consultants who would have the data as they are often the most extensive surveys undertaken for herpetofauna.

Jon

Hi Steve

None of th edata I collect is owned by my clients that is not what they are paying me for - they are paying me for my time to collect the data necessary to provide advice on what they should do regarding any protected species issues within planning applications for example. I retain the copyright to the records and I hope that many more consultants will be retaining the copyright to their records also.

Data from such studies do not have to be attached to a site name merely the general area of the country where they were collected so there is no need to keep them under wraps when it can be put to good use for research.

Jon

P.S I have finally seen evidence of smooth snakes on the M3 verge near lightwater - they have been found after all I think two adult females have been found