Egg Viability

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travisgn

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I candled my RT eggs last night and didn't really see anything (no vessels). It has been 2.5 weeks (laid 8/8). At what point can I be certain they aren't viable?

The second clutch is on the way already, my female has been pacing, clawing, and digging again for almost a week. If the first clutch isn't viable, does that mean that the additional clutches are less likely to be viable?

While I'm at it - what kind of temp fluctuations are okay within the incubator? At first the temps would only vary by 1-2 degrees, but with the ambient temp and humidity fluctuating wildly lately, it's been more like 3-4 degrees some days. I'm guessing that much fluctuation is not good.

Thanks,
Travis
 

GBtortoises

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There is no reason to assume that the second or any later clutches would not be fertile just because the first one may not be. It's not unheard for egg development to have already begun prior to copulation. Not common, but also not unheard of. If the tortoises were hibernated and introduced too late into the egg laying season the female could have very well produced unfertilized eggs. But it is also common for females to retain sperm from a previous breeding, even one that took place a few years ago. This enables her to produce fertile eggs in the spring even without being recently bred by a male. I have seen both scenarios take place with my Russians and many of my Northern Mediterranean species, especially Eastern Hermann's.

Temperature fluctuations of a few degrees are usually fine depending upon what the mean temperature already is. If you're incubating at 88 degrees and the temperatures rise 2 degrees or even more it begins to get close to fatality temperatures. I've never encountered any problems with a few degree difference in either direction. But I have had an incubator whose thermostat went bad and the temperatures rose to over 100 degrees for a long period unfortunately killing all of the developing embryo within that incubator.

Humidity fluctuation is much less of a concern as long it remains within tolerable levels. I aim for 65-75% for Northern Mediterranean and Russian tortoises but I have heard of people having sucess with humidity as low as 50% and as high as 90%.

Eggs incubating in the wild most certainly go through temperature fluctuations, especially day to night. But natural incubation usually takes longer too.
 

travisgn

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Thanks for the info. I still have much to learn.

I am trying to incubate at 88. It has fluctuated as low as 86 and as high as 90, and on only one occasion (I reset the memory every day) the high for the day was 91. I have read elsewhere that temps up to 94 or 95 are survivable, but can lead to lower hatch rates and/or shell abnormalities.
 
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