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Snakes, Coroline, onduline and I |
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Noodles
Senior Member Joined: 05 Dec 2010 Location: United Kingdom Status: Offline Points: 534 |
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Posted: 12 Jan 2011 at 11:05am |
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Gemma, I found a slow-worm under a discarded chopping
board once. I wonder what they?re trying to tell us!? Mark, try getting your tin from your local scrap metal yard. Use a more homespun, word of mouth, company such as you might find in a Parish magazine, The Yellow pages etc. Alternatively if you know, or have friends who know, farmers make contact with them. Farmers often have (roofing) materials knocking about and they frequently wish to get rid of them. As I'm sure you know, tin with an aged character seems to perform better anyhow, so you end up paying much less and getting a better working product. Failing those try your local cookware store. Pots and pans could well be the materials for 2011. The methodology for carrying out surveys to accompany planning applications or to seek similar permissions should always include visual surveys. Whether these searches are carried out or not, or indeed successful, is another matter. It would depend, I think, on the individual surveyor's experience, skill and commitment to the project. It would certainly appear in the methodology section of their report, or you would expect it to. Rob |
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Matt Harris
Senior Member Joined: 03 Jun 2003 Location: United Kingdom Status: Offline Points: 233 |
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Relating to Gemma's post about cardoors and saucepans, I guess we've all seen the 'common' species under just about every object you can think of, from discarded porno mags to fallen gravesones to chucked-out fridges, but going back to ACO's there's a difference between a herp conceivably using an ACO as a one-off, and that ACO being efficient enough at attracting herps to allow a population estimate, site clearance, or even detecting presence/absence on sites with low densities. 0.25m2 roofing felt may be fine for lizards on Dorset heaths, but I wonder how well they would pick up grass snakes and adders in marginal habitats? |
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Mark_b
Senior Member Joined: 26 Jun 2008 Location: United Kingdom Status: Offline Points: 155 |
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I have no idea why there are no slow-worms at this site. Maybe they never migrated there or couldn't migrate there? The habitat is heathland in south Wales
Yea I was hoping for a lot more animals but they didn't turn up. There were large numbers of grass snakes found through visual encounter survey only 400m away. It has already been discussed in this thread the importance of refugia placement and by using Reading's method I have to put a particular array in a particular place thus many of the refugia are not in what I class as a prime location. That may well be one of the issues but I couldn't test my theories without constructing the experiment this way. I hope to have some interesting results once I have analysed my data, which I shall post asap.
Where do you guys buy metal sheets from out of interest? How many consultancies do visual encounter surveys as well as refugia surveys (when determining presence and when catching reptiles) ? |
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administrator
Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10 |
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Rob, I don't have access to the forum database to change a user name and the function isn't in the admin menu.
Contact Chris Davis who now looks after the hosting and maintenance of RAUK, he may be able to change the user name in the database. |
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administrator
Admin Group Joined: 01 Jan 2007 Status: Offline Points: 10 |
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There are a great deal of factors involved in this discussion and I think no simple answer or single best material though factors like handling and even appearance become important in large consultancy style mitigations.
My data shows for example best performance for Onduline is on fairly uniform grassland sites. A habitat we have often encounter on development sites. Adder use refugia, but nearly all my encounters of adult adder under or on refugia are in the summer feeding grounds. .. a pointer that adult adder only tend use refugia for long periods whilst actively feeding. The pattern is similar for adult grass snakes only in this case they are either digesting or sloughing. In all I totally agree we should be flexible and open minded. If I was forced to use one material, it would be Onduline. I too can get results with simple visual survey for adder, it still remains my main technique for adder due to their reluctance near hibernation areas for example to even use refugia. An hours visual survey will often get a result where refugia survey produces nothing for months. The biggest factor though as Jon has stated is placement. I've been out on one of Jon's sites and clearly remember thinking when I saw the refugia 'that's exactly where I would have put them'. Sounds trivial but it compares to being out with many claimed reptile consultants who randomly place refugia with little hope of any of them producing animals as they simply lack a feel for the work. You either see the right places or you don't. It's simply experience of knowing where you would look visually and as many of these people have never perfected visual survey they have no more idea than a member of the public as to where refugia should be placed. For slow worm btw we should be using car doors and concrete slabs and old saucepans.. I remember lifting a car door at the Mabledon Hospital site and what I would guestimate at 40 slow worms were either in or under it. On the same site I lifted a concrete slab covering some of the underground drainage system that remained on the site, and there were 20 slow worms of all lifestages. These were not officially recorded sightings but when I check them against the tin felt survey I undertook at the site a couple of years earlier we only had a handful of slow worm show during the survey and most of these were under carpet tiles left over from a previous survey. The saucepan was on a site that produced no slow worm at all using the usual refugia materials, but under the saucepan we found a huge adult male. |
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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Well it is basically an assumption - that the peak count
of adults within a survey relates to approx 5 to 10% of the population. The idea for this comes from the data from newt peak counts of between 2 and 28% - taking the half way point is 10% - so you assume that the peak number of adults seen within a survey on one visit is say 10% of the population present - you do not know whether this is the case unless you go and capture all the animals in the survey area - for instance in a mitigation scheme - this is where rescue/capture data can help with determining what survey results could actually mean - it is only relative and not the complete picture as there is many different viables and of course you do not capture all the population - though in many cases you do end up with the majority of animals prior to destructive searches. |
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Noodles
Senior Member Joined: 05 Dec 2010 Location: United Kingdom Status: Offline Points: 534 |
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Jon,
Is that from a single peak count or are you using combined biometrics and suggesting a similar high rate of non- detection over time. Surely a well recorded site (such as yours) would lean more towards a 10% detection rate, if not much greater. Also I'm not sure how GCN capture returns can inform Slow- worm population densities, taking into account that the two species are so distantly unrelated. I'm not saying it is wrong by any means but can you explain? |
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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I suspect that it is just extrapolated from the detection
of the population in great crested newt/amphibian surveys - griffiths suggested that between 2 and 28% of a newt population is seen in peak counts - The half way point is 10% so you can assume that 10% of the population is revealed in the peak counts of a survey - From my trapping results is almost holds water for slow- worms, lizards and possibly grass snakes - the adder tends to be a much smaller percentage - this is based on the peak counts of a survey and its relation to the total number of capture animals within a mitigation project. I see that peak counts of adders tend to be around 1 to 3% of the captured population. It would be good to get some data on this to see whether this is the case. My local churchyard has a peak count of 150 slowworms - so that potentially could be 1500 to 3000 animals! The density of ACOs on this site is 140+ per Ha! far exceeds the Froglife advice sheet - 5 to 10 ACO per hectare which is not relevant to consultancy work any way J |
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Noodles
Senior Member Joined: 05 Dec 2010 Location: United Kingdom Status: Offline Points: 534 |
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Hi Jon,
Speaking of Slow-worms, I often see reference to a 5-10% detection rate of populations in survey reports. Is this based on an ACO density of 10 per ha/ and a defined number of visits? Most reports i have seen using this figure also use an indeterminate number of ACO's (generally far exceeding the often impractical recommended Froglife density for small sites)and a wide variation in survey effort. Has it just been shown that a 5-10% variation covers the broadest range of survey standards? I am often perplexed by its loose application. Cheers |
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herpetologic2
Forum Coordinator Joined: 15 Jun 2004 Location: United Kingdom Status: Offline Points: 1511 |
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No slow-worms present Scale...
Funnily enough it is Chris Reading which coined the lizard do not use ACO's in his research report. His arrays were on Dorset Heathland - many people have viviparous and sand lizards on ACOs including very undersized ACOs - less than 0.25m2 But the data is what we need. I going to test a theory out on my slow-worm population in relation to number, age and size of pieces of felt over 2011 J |
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