Small varanid sexing

[Rocket]

I understand that sexing small varanids can be quite difficult short of x-raying and using comparative observations of known sex animals or actually witnessing a mating but the general consensus is to base it on head width or size of spurs and/or spur cluster laterally adjacent to the vent.

In regards to head width, has anyone actually noted head width averages amongst males and females of species such as Varanus acanthurus, V.gilleni and V.storri? I believe, by compiling a list of the head widths of known sex animals of these species, averages can be used to benefit the baffled keeper. Obviously, animals would need to be of a minimum age and overall length to minimise risk of comparing young vs. old animals etc and not mixing up an immature male using the averages of an adult female etc.

What about average spur size? Are the spurs similar between the sexes and differ only in thei degree of taper or are they visually obvious?

I have a "female" Alice Springs Varanus acanthurus here. I would like to be 100% certain of this before purchasing a partner for "it". She is believed to be approximately three-years of age and measures an overall total length of 560mm. Her head width, measured from the upper boundary of the left to the right tympanum measured 25mm. Is this similar to the head width of other peoples' adult "female" Varanus acanthurus? I have attempted to use the spur-catchment method with the finger of which, based on this method says that she is a she.

Cheers

 

[richardsc]

its easier to tell with multiple animals,but with ridgies,the males are longer looking,longer snouted,tailed,solider of head,and even sleeker in appearance,though i have seen some very solid males so not good to go off sleekness,the females have always looked to have had shorter heads,pin headed looking in comparison,with fat looking necks,thats what i went off with mine,it can be subtle though,but i seemed to have got it right,spur size wasnt overly different,i started off with a male,so just looked for ones that looked girly by that technique,ill suss my pics and see if i can show you what i mean with my old ones,plus examples of gillens and storrs if u like,shows the differences in sex

 

[Rocket]

Sounds good Richard, thanks. I knew physical comparisons amongst adults would make it easier but I know noone keeping thewm locally to compare my one to, hence this thread. Yeah, photos of the acanthurus, gilleni and storri would be great as it will give all keepers the opportunity to compare.

 

[book]

You could also try Danny Brown's Hemipenal Transillumination technique publish from page 26 in this Varanid Journal, BIAWAK, http://varanidae.org/Vol3_No1.pdf

 

[Rocket]

Noone has anything else to contribute?

 

[geckodan]

Not long now - my books will be out and you'll have too many photos to compare. You'll have to pick a favourite method.

 

[Rocket]

No worries Danny. Can you estimate a release date for your book(s)?

 

[sesa-sayin]

sometimes hunch can be good. bought 2 "Karanda " juvies 2 years ago..felt all along 1 was a female. had kept them separate, throughout this period...yesterday, on the floor of her enclosure were 3 almost pure-white eggs....So. probably, for the first time in my life, I was correct about something.

 

[PilbaraPythons]

I hope that books coming out soon champ, any longer with my deteriorating eyesight, I won't be able to read it.

 

[Robo1]

I'm eagerly awaiting that book Danny! There are a couple of methods I use to sex ackies.

The first is Danny Brown's Hemipenal Transillumination Technique as mentioned above by book (Danny would be much more qualified to comment here!). I'd highly recommend reading the paper, it's well written and explains the technique with some nice examples. For ackies, I use a very bright LED torch with a leather cover to reduce aperture down to the size of the animals tail. It can be a little tricky to coordinate (without blinding yourself) and I find it's best done in a dark room with as little light bleeding around the tail as possible. I find adults much easier to sex, but they do require a very bright light source (LEDs work well because they don't give off a lot of heat).

The second method uses their spurs. Both males and females have spurs look similar, there are some visual differences but it's much easier to go by feel rather than sight. If you rub your finger tip over them (towards the head), a males spines will catch on your finger while the females spurs are softer and will not. It also helps to gently pull the back leg forward a little to expose the spurs. Of course, this works best when you have one of each so you can feel the difference.

There head size can be another good indicator. Males tend to be broader in the head near the back of their jaw when compared to their neck size. Females heads are more streamline and slender.

 

[geckodan]

I hope that books coming out soon champ, any longer with my deteriorating eyesight, I won't be able to read it.

Most up to date book never published.

No worries Danny. Can you estimate a release date for your book(s)?

I could, but then we'd both be confused and dissapointed - pre release posters at the pet industry expo has got to be a good sign I think.