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Individual Adder ID

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    Posted: 08 Mar 2006 at 12:04pm

Hi All,

Carrying on from another thread where I requested information regarding techniques for adder photo ID I've found that

Benson, P.A. (1999): Identifying individual adders, Vipera berus, within an isolated colony in east Yorkshire. - British Herpetologcial Society Bull. 67:21-27

is published on the web at:

http://www.allerthorpe.org.uk/pages/identifyingadders3.htm

I'm also looking for a copy of the following paper if anyone can help out:

Sheldon, S & Bradley, C. (1989): Identification of Individual Adders (Vipera Berus) by their Head Markings. British Journal of Herpetology Vol. 1 pp. 392-396.

Ta



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Post Options Post Options   Thanks (0) Thanks(0)   Quote herpetologic2 Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2006 at 5:25pm

 

Hi Gemma

I have a copy of that paper - it looks at the dead markings and divides them into three - apex of zig zag, H or V and eye spots -

When you get good close up photos of the adders head I tend to look at the individual scale markings - you can then match these up in different photos - this allows for positive id with photographs of animals before sloughing, or light conditions etc also you would hopefully be able to id skins from this method

Skins if collected can be cut along the ventral surface so that they can be pressed inside out on a white background - I remember reading about this in an English Research report on reptile survey methods

Here are two examples of male adder skins (you can sex the skin by the number of sub caudal scales, if it is complete

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 08 Mar 2006 at 6:00pm

Hi Jon,

I'm beginning to get the idea, I've been looking more closely at some of my images and can see now how the head scalation can be mapped from a number of images and scale groups counted, see below:

It has come as a bit of revelation just how much variation and individuality there is in the scale patterns, this along with the head markings is getting towards a 'finger print' and can also see from your images just how easy it will be to identify a known animal from a slough. Tony mentioned this a while ago, though it hadn't really dawned on me how to go about it all.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 3:41am

Jon,

For subcaudals Smith gives 32 to 40 males, 27 to 35 in females, (with annoying overlap) is this about right, or have later workers improved on this to your knowledge?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote herpetologic2 Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 3:56am

 

Another thing that people may want to look at is the actual scale arrangements on the head - to add to the markings - all these pieces can be used to determine an individual - so when you dont have all the pieces - say the animal hasnt sloughed yet - markings would be harders to determine but the scale pattern may help determine the individual. NB - you can use scale patterns to id female lizards!

I also meant to say head markings in my last post. I am putting together all the individual adders head markings I have photographed at a study site from the last three years - I know that I have seen the some individuals over successive years - I have also put together all the grass snakes - I have 40 animals here - it will take a bit of time i think

Jon

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vicar Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 4:12am

Gemma,

I definitely find the variation in head scales an excellent discriminating factor, but, as you get a large collection of head scales, it can be a real pain comparing each one to see if you have a match.

One solution which works for me, is to compile an ID file which has various images of the individual looking at different aspects. In addition I highlight the particularly unique features of the head scale pattern. How you choose these features is, at the moment, subjective, its what draws my eye as unusual.

Here's an example: Several obvious improvements can be made, but it does work :P

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 4:26am

Benson coded individuals by counting scale groups to form part of the code for each animal.

the 5331052 bit relates to the number of scales in groups 1,2,3,4,5,6,7, respectively as shown above. I'm not convinced yet by my labelling and identification of the groups, but practice makes perfect and all that. Though some animals will have the same code for scalation pattern, it should cut down the number of images you have to check to find if you have encountered the animal before.

I've known some individuals for years, I know for sure I see them quite regularly, it is now getting to the point though where I'm visiting more sites and the number of visits is more restricted due to work etc. So I'm really aiming to get an ID system that can be relied on from a single encounter.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote administrator Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 4:34am

Hi Steve, posted at same time there, this looks a great idea, perhaps incorporating the above system of scale group counts, some of the subjectivity can be taken out? Though I think there is value in having some subjective things that just catch the eye, particularly when trying to ID in the field.

What I'm hoping is that the scalation coding and other coding (see the sand lizard thread) will help pull a small selection of record cards quickly from a large set. Then it will be easier to compare just a small group of ID cards.

Biggie, is a whopper eh! I can see it just from the head shape

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Post Options Post Options   Thanks (0) Thanks(0)   Quote herpetologic2 Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 5:47am

 

Brillant

I am going to look into this technique for my photos

Jon

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Vicar Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2006 at 7:47am

I like the Benson approach, but am having just a little trouble applying it. How would you codify 'Biggie' above ? I'd like to compare results :P

 

(BTW, I might be having a 'blonde' moment, but is there a group-5 on your example?) 



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