Reptile & Amphibian Forums

Hey guys. I decided to re-start this thread at the top of the page so I would quit having to scroll down to check on it (yes, I'm lazy!).

In answer to your questions Tigergenesis, Brian Schnirel of the former Southern Florida Corucia Research Center (I've no idea what it's called now) seems to be the originator of the C/A biometric ratio. I vaguely remember him saying that he had tested it only on about 10-15 animals. He also pointed out that it is not reliable for juveniles.

For other morphometric indicators, you should take a look at Luke Harmon's 2002 article on PTS in Herp. Review. He measured several PTS on Santa Isabela and found that there was a slight (albeit statistically insignificant) difference in TL vs. SVL in males and females. He did use a small sample size, so with a larger sample, who knows what the results would be?

So far, AFAIK, no one has come up with a proven method to sex these animals morphometrically. And it may never be possible. Remember that there are morphometric diffferences between skinks that originate from different islands, and the typical hobbyist (or zoo, or breeder, etc) has no clue which island the animals come from. Trying to compare body measurements for animals from different islands may be much like comparing apples and oranges. We just don't know enough about these animals yet!

However, one method of sexing that was discussed here about a year ago was genetic testing. There is a company out there that will develop a genetic test specific to your species if you give them several (~30, IIRC) blood samples and about $3,000. After the test is developed one would only need to send in a blood sample from their new skink along with a small fee to determine the gender of the animal - at any age.
Any big spenders around here?

Thank you! I searched the archives and found some more info to look over.

At what age is the C/A ratio best? I thought I had found one post where someone said it was easier to get accurate results when they are younger because they haven't put on fat, etc to skew the results.

I also read about the test with another males shed. Will a male react to another males shed at any age? I'd love to try this test (just need some shed from another male - anyone want to mail me some? ), but my little one is only 3 months old - is that too soon?
-----
Check Out My Albums

1.0 Ball Python "Aragorn"
1.0 Bredl's Carpet Python "Strider"
1.0 Kenyan Sand Boa "Gimli"
1.0 Saharan Sand Boa "Frodo"
0.1 Rough-Scale Sand Boa "Arwen"
1.0 San Felipe Rosy Boa "Legolas"
0.1 California Kingsnake "Gentoo"
1.0 Mexican Black Kingsnake "Indigo"
1.0 Snow Corn snake "Chile"
0.1 Okeetee Corn snake "Amazon"
1.0 Crested Gecko "Willow"
0.0.1 Irian Jaya BlueTongued Skink
0.0.1 Monkey Tail Skink
0.1 Australian Cattle Dog/Pointer "Kira"

Not speaking from experience, but I would guess that juvenile males wouldn't show much of a reaction. Seems to me that you would have to wait for them to become sexually mature.

Also, I would be leery about introducing the skin of an animal I didn't know into my animals' cage. The potential for spreading disease or parasites is too great, IMO.

Zeteki,

I see many posts and measurements on Corucia with the C/A. Where did you find that it was only done on 10-15 individuals? I have used it and it seems fairly accurate on Corucia I have measured.

Tane

I was saying that when Brian developed it that is how many animals I remember him saying he used to do it. As for how often it's been used since then, I can't say. And how often it turns out to be accurate? I have still less data.
Remember that just using it to say "This one is a male and this one a female" doesn't do much in terms of supporting the accuracy of the measurement until there is definitive proof in the form of an observed hemipenes or offspring.

I've used it, in combination with attempted eversions, to try to pin down what my animals are, but with the exception of one individual still don't know if the results were accurate.
Have you found it to accurately reveal the sex of your animals, and if so, at what age did you find that it was effective?

It wouldn't make sense to devise a Ratio if it wasn't tested against proven animals. Yes, I have tested against proven Corucia by virtue of breeding activity and actual births. Nothing is absolute but it is realiable enough to be used as an additional method of sex determination.

Tane

Z,

To answer the latter question, A 4 month old juvenile reads .63 and by the small tapered head and fuller body also appears female. I will keep you posted.

Tane

np

At what age does the C/A ratio seem to become an accurate method to use?
-----
Check Out My Albums

1.0 Ball Python "Aragorn"
1.0 Bredl's Carpet Python "Strider"
1.0 Kenyan Sand Boa "Gimli"
1.0 Saharan Sand Boa "Frodo"
0.1 Rough-Scale Sand Boa "Arwen"
1.0 San Felipe Rosy Boa "Legolas"
0.1 California Kingsnake "Gentoo"
1.0 Mexican Black Kingsnake "Indigo"
1.0 Snow Corn snake "Chile"
0.1 Okeetee Corn snake "Amazon"
1.0 Crested Gecko "Willow"
0.0.1 Irian Jaya BlueTongued Skink
0.0.1 Monkey Tail Skink
0.1 Australian Cattle Dog/Pointer "Kira"