Some people say Temps have no influence on the sex of snake eggs, others say they have experienced TSD themselves with their own snakes.  One person told me, that you "must" split the clutch into 2 even groups and then incubate them at different temps, and do this over several breeding seasons, with different pairs of snakes, or you can not prove anything.  I don't think splitting a clutch into 2 groups makes any sense.  What if the sex was determined at conception, or later, during the formation of the eggs in the female?  It could be that the temps in which she is being kept, has influenced the sex.  That would still be considered "Temperature Sex Determination".  Would it not?

My Results

          Initially, I was keeping my Snake Room at 85 - 86 degrees (29.4 - 30 Celsius) at all times.  I was just a collector of exotic venomous snakes, mostly Cobras, but also some Oz/PNG Elapids, and a Nile Crocodile.  The first specie of snake I ever bred were Eastern (Common) Brown Snakes.  I bred them in Jan. 2003 and Jan. 2005, but never could get them to eat, and they didn't survive.  They were extremely small.  Smaller than any Corn Snake hatchling I've ever seen.  Also, in Jan. 2005, I bred Sri Lankan Spectacled Cobras, without cooling them.  The snakes were kept at 85 - 86 degrees (29.4 - 30 Celsius).  They bred at those temps.  The eggs formed in the female, were laid, and were incubated at those temps.  There was a 12 . 5 sex ratio.  That is 12 males and 5 females for those of you that didn't know.

          I moved to Florida in Sept. 2005, and then I got more into breeding.  I was still keeping the Hot Room at 85 - 86 degrees, but I started cooling the snakes before breeding.  After cooling, I slowly warmed the room back up to 85 - 86 degrees, and after they shed, I put the snakes together.  The following information is on my original pair of Yellow Phase Equatorial Spitting Cobras (Naja sumatrana), as I have bred the same pair together for 6 years in a row and kept exceptional records.

          The first year they were kept at the temps mentioned above, all year, then cooled, and then warmed back up to the same temps.  They were introduced, and they bred at those temps.  The eggs formed in the female at those temps.  And, the eggs were incubated at those temps.  I incubated the eggs in a 9.75" clear plastic deli cup with the holes in sides of the cup covered with tape, and just 7- 8 pinholes in the deli cup lid, so that no bugs could get in, but the eggs can breath.  A little condensation forms on the inside of the deli cups.  I used a 50/50 mix of vermiculite/water by weight, and left them sitting on a shelf in my Hot Room, at 85 - 86 degrees.  After 64 days, 6 of the 7 eggs hatched and there was a 5.1 sex ratio.  The 7th egg did not hatch.

          After I saw the 5.1 ratio that first year, I talked to some friends about it.  They suggested I lower the temps.  I immediately lowered the temps that I kept the snakes at throughout the year.  Then I did everything exactly the same, with the same pair of snakes at the new, lower temps.  The third year, I lowered the temps more, but only slightly, and did everything else the same.

          The chart below shows that temps can/do have an effect on the sex of the offspring, other than the eggs taking longer to hatch at lower temps.  If you split the eggs of one clutch, into 2 groups, and the sex has already been determined by temps or other factors during their formation in the female, then your test is showing you nothing.  But, when you breed the exact same pair of snakes, over several years, and everything else is the same, except temperature, and you continuously get less males and more females at the lower temperature range, then TSD (Temperature Sex Determination) is taking place.

       **  In July 2008, I finished my new Snake Room.  It was built inside a steel building, with 2x4 walls, 2x6 ceiling joists, and it is insulated just like a house would be.  I put Luan on the inside walls.  It was then painted white.  I have a good sized A/C unit for cooling, and two oil-filled electric heaters, each controlled by separate Johnson Controls, on separate breakers, and 4 ceiling fans circulating the air.  Shortly after it was finished, and the smell of paint was gone, I moved the adult snakes into the room.  Shortly after that, mold started to grow on the walls and ceiling.  I washed it off, but it grew back.  I purchased a dehumidifier and it solved the problem.  But, maybe too late,  I lost a few, otherwise healthy, adult Corn Snakes and King Snakes, and then a few months later during Brumation, I lost my male breeder N. siamensis, my male breeder N. melanoleuca, and a CB'06 female N. sumatrana.  The temps never went below 55 F (13 C). and everything was healthy.  The N. siamensis and N. melanoleuca may have been old animals, but the N. sumatrana was produced here and was otherwise healthy.

          Before moving the adult snakes to the new Snake Room, they were in bedrooms in my house, and I was using the same type heaters, but using Helix Controls instead of Johnson Controls.  The humidity was naturally much lower, so I didn't need a dehumidifier in the house.  Maybe the temps in the new Snake Room were not as low as I thought, since I was using new heat controls and different A/C unit. Maybe the very high humidity or mold had some effect, maybe not, but as you can see, I did everything else the same, but that year I got more males than females.  That was also the first year that the eggs were laid in the new Snake Room, and incubated in the same room in my house as the 3 prior years.

          In 2010, I did everything the same as in 2009, but the Temperature and Humidity remained more constant, ie: no radical rise in humidity.  The dehumidifier has worked very well.  The same two adults were bred again, and they produced 10 eggs.  The largest clutch thus far.  One egg went bad quickly, and the other 9 started hatching out after 74 days, and finished hatching after 75 days.  The sex ratio is 4 . 5 once again, showing a higher number of females, at the lower temps.

          In 2011, the same pair bred again on 02/08/11.  Data coming as it happens.

     **  See in the chart below were the problems with humidity and mold may have caused abnormal results.

Naja sumatrana  SumY-001-AD-F

        Important Note:  In the above and below charts, where it shows temperature, the temps you see are the temps the snakes were kept at during the year before breeding, and the temps at which they bred.  The eggs formed in the females at that same temp, and the eggs were incubated at that same temp.