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Leeway Corucia Research Center (LCRC)

Sex determination in Corucia:

Key Words:

probing, behavioral observations, ecdysis method, fecal method, general anatomy sexual dimorphism, C/A biometric ratio, vent scale sexual dimorphism, DNA sexual analysis, Introductions.

Introduction:

Methods of sexual indication of the Scincidae species: Corucia zebrata (underlined) will be discussed here.

Probing:

Probing Corucia zebrata (underlined) has always proven indeterminate. It accomplishes nothing but one having a very angry skink. The jaw strength of these guys is incredible and you want to avoid being bitten at all costs.

Behavioral Observations:

Behavior observations can be a determinate factor although variations do occur. two males will almost (but not always) fight. Males, usually to express dominance, will twitch their tail similar to that of a cat. Females can occasionally attack each other as well.

Ecdysis method:

A gentleman by the name of Justin once suggested using the shedded skin of a known male in an enclosure of a new skink. if the newcomer reacted to the skin in a hostile fashion and engaged in the cat tail twitching posture, it would denote a male. However, in practice, this has proven indeterminate as well.

Fecal Method:

Another attampt in a variation of the ecdysis method is to put feces from one Corucia enclosure to that of another. This is not a wise approach. In addition to upsetting the entire Circulus of the introduced enclosure, A resident circulus skink may get smeared with the foreign poop and get attacked by a resident skink. With this method, hostility could derive from both male and female. In addition, as Sherri has pointed out, This method could spread possible contagion from one enclosure tio another. Even if both Circulus groups in each separate enclosure appear healthy, there may be no resistence to the introduced pathogen in the new enclosure.

General Method Sexual Dimorphism:

Generally males have a 'blockier' head in width and females a narrower , shorter head in appearance. actually, the head size can be similar. It appears different when compared to body width. Females even when not gravid, have a more pear-shaped body in general and the males more straight and streamlined. These differences can be subtle, however.

C/A Biometric Ratio:

A biometric formula ( C/A biometric ratio {Latin: C= Caput (head) A = amplus (width) }) designed at the former South Florida Corucia Research Center in 2001, can give a guide to sex by measuring the width of the head and dividing by the width of the girth of the midsection from the adaxial view.. If the results are less than about .73, the Corucia may be female. If above, then a male is likely. This method also is not absolute. Of course, a gravid female will have significant girth to give one a good idea of sex and as such throws the ratio off in the case of the C/A. If the Corucia is not malnurished, a thin build Corucia give a better chance of being a male.

Vent Scale Sexual Dimorphism:

Another more recent observation is in the vent area. Males supposedly have a v-shape to their posterior vent scales in a male. So far, there seems to be variance in this method as well.
As far as the vent area is concerned, the Scincidae possess no femoral pores so that avenue of sex determination is a dead end.

DNA Sexual Analysis:

Sex determination by a DNA blood sample is still years in the distance. Unlike Humans that have the male with the heterogametic XY combination and females with the homogametic chromsomes XX,. lizards, such as Corucia, have the male having two of the same chromosome (homogametic) ZZ, whereas the female has heterogametic chromosomes ZW.

Introductions:

The most positive sexual indicator is introductions to different individuals. A trained eye will determine by behavior who is who genderwise. One must be quick and ready to separate two introduced combative Corucia. Extra precautions must be made to avoid being bitten. A U-shaped separation bar sometimes can be useful.

Conclusion:

In short, there is no clear - cut answer but to combine a variety of methods and hope for the best.

Sincerely,
Brian
LCRC

Last edited by Brian - LCRC/L2 (Today 04:05:24)

Leeway Corucia Research Center (LCRC)

Another popular idea that has come in to play lately is ultrasound for sexing Corucia. In my experience, as well as other experienced Corucia caretakers, is that ultrasound is fairly expensive & the results often clouded, literally. Corucia, if you haven't noticed, are very 'gassy' lizards in which many times an ultrasound will prove inconclusive because of this. Brian was right with the above advice but, I might also add, male Corucia tend to do a little dance when interested in mating. I've seen this many times. It's a dance in which they have a tendency to do a bobbing & weaving motion with their head. Bump the humidity up & do alot of misting .... There really is no set time in the day or evening that one can witness this. Even though Corucia are known to be crepuscular, when it comes to mating & the ritual beforehand, they don't really care what time of day it is!! In the wild, mating may commense and spike with the start of the rainy season. With Corucia kept outdoors in Southern Florida, mating occurred with more intensity and frequency during rainshowers and thunderstorms. By the way, the ratio method, if you use it, again is called the C/A biometric ratio (Latin: C= Caput (head) A = amplus (width) ). You may post pictures if you wish us to try to sex them with this method. The picture needs a clear shot of the head and abdomen as seen from above. Positioned vertically really helps too with the body as straight as possible. Sexing Corucia is not easy. The C/A has worked for us about 75-80% of the time. The rest of the time, it's just observations, personality, shape of head &/ or body etc.

Sherri
LCRC