# Temperature sexing



## Itort (Apr 17, 2010)

What are the pros and cons of manulateing temp to determine sex of hatchlings ? Some say it can cause split scutes. Are there other consequences and does this warrant the practice ?


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## egyptiandan (Apr 17, 2010)

The consequences are you get more of one sex than the other. I don't see that you can stop it unless you don't incubate. If you incubate eggs you are practising sex determination of your hatchlings, whether you want to or not.
Now if you mean should people hatch at higher temperatures to get more females and is that detrimental to the hatchling. Than yes that is another story.

Danny


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## Itort (Apr 17, 2010)

egyptiandan said:


> The consequences are you get more of one sex than the other. I don't see that you can stop it unless you don't incubate. If you incubate eggs you are practising sex determination of your hatchlings, whether you want to or not.
> Now if you mean should people hatch at higher temperatures to get more females and is that detrimental to the hatchling. Than yes that is another story.
> 
> Danny



Yes, this is what I'm speaking of. Incubating at higher temps to get more females.


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## egyptiandan (Apr 17, 2010)

Now we are getting somewhere 

It depends on the species we are talking about as maximum temperatures (temperatures that kill the embryo) are different for different species. I would be more worried about going over the maximum temperature, than worried about having deformities from temperature. When you do get a hatchling that does have a deformity, is that caused by high temperatures or genetics. The only way to find out would be to hatch the same number of eggs it took to get a deformity, at a higher temperature, at a lower temperature.
I've gotten just as many deformities at middle temperatures as I have at high temperatures.

Danny


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## -EJ (Apr 17, 2010)

If you allow the incubator to vary you can get a decent mix. 
If you don't incubate the eggs and it averages 60 to 70F what do you think the hatch rate will be?




egyptiandan said:


> The consequences are you get more of one sex than the other. I don't see that you can stop it unless you don't incubate. If you incubate eggs you are practising sex determination of your hatchlings, whether you want to or not.
> Now if you mean should people hatch at higher temperatures to get more females and is that detrimental to the hatchling. Than yes that is another story.
> 
> Danny


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## GBtortoises (Apr 18, 2010)

I incubate all eggs of all all of the tortoise species that I breed at higher temperatures to produce predominately female offspring. I have yet to produce 100% females in any given species and I doubt it will happen. As best as I can tell based on my own holdbacks and feedback from people who have purchased from me I am generally getting a ratio of 4 or 5 females for every 1 male produced. This is by no means accurate enough to set in stone since many of the people that I have sold to I've lost contact with over the years. It is only based on the ones that I can confirm. 

I do get a few each year, regardless of species and temperatures that have extra scute seams. I think temperatures play a major role in producing tortoises with extra scute seams, as might low incubation humidity levels and temperatures to constant. As many people have pointed out, probably genetics does too. I have had in the past and currently have wild caught tortoises with extra scute seams too. Some very numerous. I consider it purely cosmetic and it doesn't bother me at all. Other than the extra scute seams they are perfectly healthy and normal in every way.

In the case of most tortoise species in captivity there are plenty of males, maybe too many. You really only need one male to breed with several females. Given the territorial and aggressive nature of males of most species it is difficult to keep several together in a captive situation based on small enclosures (compared to unlimited wild territory). According to some Testudo researchers the ratio of male to female in wild populations is nearly even and in some cases more males are present. This is probably natures way of ensuring that each female will have a very good change of producing fertile eggs each season. To some extent it probably provides ensures a constant genetic diversity too.

I see no problem with making every attempt possible to produce more female than male offspring in captivity, even if it does mean some tortoises with extra scute seams as long as those same tortoises are healthy and normal in all other ways.


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