RAUK - Archived Forum - adder sexing help

I observed about 8 different adders on my last trip (9th March, Lincolnshire), but none of them seemed particularly pale, so I assumed they were all females. However, after reading the post about rostral scale frame marking and seeing pictures of male adders arthat don't look so pale, I'm now not at all sure what I saw!

I have read that a female has a shorter tail than a male, but at this stage in my experience, I'm not sure what contitutes 'short'. Does anyone have a good comparison picture of the tail length of a female and a male?

Here are some pictures from my trip and my guess at the sex of each snake. As you can see I'm still a bit puzzled. Any comments welcome. The pictures are not particularly good, but maybe good enough to determine the sex?

adder1 - male due to tan colour dark black diamonds and rostral scale frame? Not sure what can be said about the tail.

adders2&3 - male due to pale tan colour, dark black diamonds and rostral scale frame? possible female underneath...but isn't it too early for this kind of behaviour?

adder4 -male due to tan colour dark black diamonds and rostral scale frame?

adder5 - ? similar coloration as adder4, but less distinct rostral scale frame

adder6 - ? similar coloration as adder4, but less distinct rostral scale frame and does this contitute a short tail or long tail?

All those adders are male - including the female - Adders 2 & 3

The tan colour will go when they shed their skins - you will notice that the snakes have a lighter head colour from the neck upwards (just slightly)

I have some photos of tails for comparison I can post these ASAP

Jon 

I always describe the females tail as looking like an after thought, it isn't only shorter it looks like it was stuck on separately, whereas the males tails taper smoothly. Jon has some good pictures of this.

I would say all your images are of males - the stripe is practically pitch black and well defined in each as are the side blotches, at this time of year forget background colour, it is very misleading espececially in comparison with the 'wisdom' found in many text books.

You should find some threads on here from a couple of years ago when I was struggling with all this, now it seems obvious

(I shall now wait to be shot down in flames for getting it wrong LOL)

I cannot readily track down the information about rostral scale markings (what are they? I dimly remember reading something about them on the forum last year?) - can someone either signpost the relevant thread or otherwise explain please?

What I did discover from looking back at some of last year's Adder postings (including my own) is that the animal I saw yesterday that I recognised from March last year was behaving in the same way as then i.e. coiled-up, relatively languid and happier to be approached than other Adders out at the same time.  Coincidence or a sign of an individual behaviour trait (I suppose "personality" would be putting it too strong, and not a proper scientific term!).  Or is it just that the level of caution shown by an Adder changes with age?

Peter

Seems I posted at the same time as Jon last night, simply repeating the same information.

The one key thing that is easy to spot is the stripe. Pitch black and high contrast to the background colour (whatever that might be i.e. pre-slough etc) is usually a male. The females tend to have lighter stripes which are less defined, usually brownish rather than pitch black - the same is true of the side blotches - you will spot this before anything else then you can look at tails etc.

Here are some females to compare to the images above, forget the background colour and look at the stripe - here the difference remains even with the pre-slough males above, the stripe is black in the animals above even though the background colour may currently appear to be brownish and thus typically female.

I had never heard about using rostral scale markings to sex adders.  I have just finished trawling through my adder photos to check, and it is consistent.  The rostral colour has also help me ID a male that I have never been 100% on the sex.  However, last year I found a very large blue/silver 'male' adder with a black zig-zag.  I remember commenting at the time that 'he' was very well fed and almost looked gravid.  The rostral scale suggests it was a female.  I recall Thomas Madson has also reported blue female adders in his publications.  What are peoples thoughts on the sex?

Ax

I had never heard about using rostral scale markings to sex adders. I have just finished trawling through my adder photos to check, and it is consistent. The rostral colour has also help me ID a male that I have never been 100% on the sex. However, last year I found a very large blue/silver 'male' adder with a black zig-zag. I remember commenting at the time that 'he' was very well fed and almost looked gravid. The rostral scale suggests it was a female. I recall Thomas Madson has also reported blue female adders in his publications. What are peoples thoughts on the sex?

Thanks for the info Wolfgang.

I agree with your comments on the pictures. Do people probe adders? I once saw what I thought was a female, purely because of size, but everything else was male - although I didn't know about rostral scales then. There is a wide variation in adder colours and patterns so maybe there are males that are a bit more feminine (to look at) and vice versa. Natural selection at work?

No need to probe adders I feel - and I wasnt convinced by the rostral scale colouration either - though this was from a german paper I believe and it led the guys n gals in Kent to rename an old adder known as knackered nora to knackered Norman or something like that

I normally go on the shape of the tail, colouration and the rostral scale markings may help with this - if you cannot be sure adult snake would suffice until such time you have seen other behaviours which suggest which sex etc

Jon

Hi All,

Firstly to Wolfgang... Your adder 'head-on' shot looks like a male to me using the described method for sexing adders by rostral and pre-nasal shields..

I refer to the link that gives straight forward examples but it should be used in conjunction with shape of tail and other colour variant like stripe definition if you are unsure.. See:

http://www.herpetofauna.co.uk/forum/forum_posts.asp?TID=1560 &KW=rostral+scales

I am surpised that you all seem to doubt the obvious, I have now used this mehtod in a number of counties and not just Kent, thank you Jon, and it has worked extensively.. It comes with experience and clear photographing techniques in distant situtations.

Again I refer to the above image from Wolfgang, the flecks on pre-nasal shields and the colouration on the base of the rostral scale suggest a male adder to me.

Continue the good work folks and use what ever method you are confident with, for all other seek advice from those who know.

Checklist: Colouration (background and zig-zig), Tail shape, rostral scale and pre-nasal shield colouration or lack thereof, caudal scale counts (pairs)..

These methods should get you in the ball park and I'm sure your local ARGs could help out with the rest. Be sure that there are some individuals that do not fit any of the criteria, like smooth newts without spots on the chin.. Use a combination of techniques and you will gain more success with your animals.

Also to correct Jon's comment about Nackered 'Nobby'.. This animal had previously been described as a female but had not been caught or identified otherwise. On one ocassion I went out and had a good look at her (him) and decided that the colouration of rostral and pre-nasal shields showed that indeed it was a male. With Richard Griffiths we caught the animal, checked caudal scale count and for hemipenis and I was correct in identifying this early record as a male...! 'Nackered Nora' became 'Nackered Nobby' over night...!

Nackered because he had been beaten up over the years and has all kinds of scars and scale deformaties... Probably by badger and/or bird predation.

Kind regards

Brett Lewis

Hi Bret

the head on shot seems to have light borders and no rostral fleck as described in the methodology? though there is some dark marking to the borders of the rostral scale highlighted in new pic

Is that what you mean Bret?

Jon

Hi Jon, Wolfgang..

Jon, that is what I was refering to and shows the detail that you would look for. Although not the most obvious example.

Wolfgang,

I admit that it is not clear all the time and at times like this you should use other methods as you quite rightly did with the tail and possibly sub-caudal counts.. When Petra discussed those animals without markings I think she could have been refering to possible mis-identifications just as easily as abnormalities to the colour morph.

You should note that the rostral scale colouration does not have to be as coloured as your second image, but could simply be a frame around the rostral scale or darkened lines on the pre-nasal shields or any combination of those. In most cases females lack this colouration or have very faint shadows.

In all circumstances I think it right to test the hypothesis. I would be very interested in your/other people's populations to get a real grip of this. They would need to be compared with tails and sub-caudal counts to be certain I feel. All I can say is that here in Kent, it has been proven true with each animal we have encountered, captured and examined.

Can I also stress that observations like these should be used with caution when encountering animals pre-ecdysis as this time period may give an increased chance of a false -ve or +ve if used as the sole method of sex determination.

I look forward to hearing from those of you who would like the challenge of some real useful research..

Kind regards

Brett.