# Incubation Temperature Determines Sex?



## sunshine_hugs (Jul 4, 2013)

Okay, so please don't laugh, as this is totally new to me...and I might be posting in the wrong section, but I didn't know where else to put this. 

I was recently visiting a friend who adopted a redfoot, and is going to adopt a hatchling from the same people I adopted mine from. They told me that all the hatchlings were males. I was confused, as I thought they had to be much older to determine sex.

They said (I don't know scientific terms, and I don't breed...mine are all hatchlings) that the incubation temps determine sex, and the owners of the parents said all the hatchlings were males because of the temps outside right now (we live in the Caribbean, so their torts are all housed outside, and lay in their habitat).

I guess I would like to understand this more...but dumbed down a little. 

Also, will I have problems with 5 males when they're older?


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## JoesMum (Jul 4, 2013)

It is true that incubation temperature determines gender for egg-laying reptiles.

In a large buried clutch the cooler eggs on the outside will be the opposite gender to those kept warmer in the centre of the clutch.

Tortoises can be incubated to be a particular gender, but it is not 100% accurate. Slight variations always occur and those 'bred to be male' can turn out to be female once they have matured and vice versa. There is no cast-iron guarantee.


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## Arizona Sulcata (Jul 4, 2013)

Temperature can increase odds one way or the other but your best bet it to always assume you're getting a 50-50 shot between males and females because in reality it can go either way especially if you aren't familiar with the breeder. 

To answer your last question, yes having 5 males together will create problems in the future. Granted, I highly doubt you'll have 5 males.


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## Tom (Jul 4, 2013)

It's called temperature sex determination. TSD. The only tortoise species that I know of where these temps are studied under lab conditions and known is the sulcata.

In the real world, people's thermometers can be off a couple of degrees, there can be variations in temperature due to seasons and room temps. Lots of things can go "wrong". If these eggs were incubated in the ground, there is no telling what you've got. Come back and let us no now if a few years.

Redfoots often get along in groups, so you might be okay.


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## sunshine_hugs (Jul 4, 2013)

Thanks for all the info everyone. And yes, they were incubated in the ground...and the breeders don't have temp. guns or anything like that. They rescued adult tortoises, that eventually made babies. They are treated & housed very well (we visited their place)...they are placed in as natural of an environment as possible. 

I believe there were only 8 hatchlings in this clutch.

I was totally prepared to wait a few years to find out the sex...so here's to a few years of hoping for not all males (just to avoid problems).


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## Kapidolo Farms (Jul 4, 2013)

http://www.bio.davidson.edu/people/midorcas/animalphysiology/websites/2004/Kinsell/page2.htm

This web page gives the basics. It has been critically observed in the field and in labs for dozens of species. There are egg treatments that can thwart this natural phenomenon, and then each egg is it's own self, meaning it may not follow the trend.

There is a critical point in the incubation period where for the most part this sex determining pattern is triggered, and incubation temps before and after wil not change the sex as determined during that critical time period.

So, without regard to what the breeder has told you, it is unlikely that you will have 100% one sex or the other. That critical temp and point in time is so small a window that eggs in the bottom of the nest can be of a different sex than eggs in the top of the nest.

When some labs do their experiments they use highly conforming temps for the whole of the incubation period which can mask those two critical points in the process. Other labs have explored this phenomenon to such an extent that they have pinpointed those times and temps for specific species. Some workers in this field have developed chemical (hormone) treatments that will push all the hatchlings towards one sex or the other despite the incubation temps.

Will


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## sunshine_hugs (Jul 4, 2013)

I am finding this fascinating. Definitely something I want to learn more about.


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