Overnight Temps in Tortoise House??

[Markw84]

I've got a question... I definitely don't want anyone to think I am proposing this as a way to do things, but I do want to get feedback.

I got my first tortoise is 1961 and was hooked. It was a CDT and I lived in Southern Calif at the time. Older, and with my own home and acquired building skills - I transitioned to Sulcatas in the 80s and a few Leopards. I have successfully been breeding Sulcatas since 1996 with several hundred hatchlings. Went through all the frustrations of trying to figure out pyramiding. Spent quite a few late hours on the phone with Dr Fredrick Fry, Frank Slavens at Seattle zoo, Sean Mckeown then at Honolulu zoo, visiting the San Diego zoo, etc etc. No matter what I tried with my hatchlings, they all pyramided to some degree. However I did have pretty good luck once I moved them outside at about 5-6 inches. I even transitioned to enclosed chambers for my hatchlings and young back in 1996 when I moved to the central valley of CA - but mainly out of frustration to better control temps. Did keep them at 80 with basking to 100 and overhead 4" fluorescent UV bulbs while inside. Didn't try humidity!!

Once they were 5-6 inches I would keep them outside in a large double enclosure that was 5000 sq ft. I had an 8' x 8' house for them to go into at night that was heating and had 3 flood lights hanging for basking lights.

SO... TO MY QUESTION

I did not believe from my experience in wine cellars and caves, that the nighttime temps in a burrow even in the southern Sahara would be much above 70. They have developed a nesting habit unlike most chelonians of digging a body pit to get their eggs to 18" or so to get the temps in that 80 - 90 range. I theorized some eggs laid dormant a time at that waiting for temps to get warm enough at that 18" depth. At 20 feet deep or so in their burrow, can't imagine temps over mid 70s in the warmest season. So I never heated the tortoise house in the warmer months. The nighttime temps would drop into the high 60's in their house. In the cooler months I would heat the house to the mid 60s and have the floods on for 13 hours so they could warm themselves to the mid 80s They would warm up and come out and graze, then go back in. Some days they would not come out at all if it was totally overcast. They would definitely slow down and be less active. I have used this setup to this day. I have raised several dozen tortoises, and - knock on wood - never have lost one that was kept this way. Never had to treat for any diseases, or impaction, and they successfully breed.

All the threads here insist the tortoise house must be kept at 80. even at night. I would love an open discussion on why this is necessary when all my experience has been so positive without that.

Thank you for all your input. I have come to respect so much what so many of you have done.


Here is a view of a portion of the tortoise area I used from 1996 - 2014 I rarely fed my tortoises other than when visitors wanted the tour, or an occasional class on a field trip. They grazed on what was growing naturally.


This is my enclosed chamber I built in 1996. Yes, sadly that's artificial turf. Note the pyramiding!



Here's my results. I got Diego in 1991 as a hatchling just after he hatched at the San Diego zoo.


Here's Crush with one of this year's babies... See how he pyramided, yet smoothed out once outside. I hatched him out in 1995. He's 26" SCL and 113 lbs as of this morning.

 

[Tom]

This is a great post and great info! I'd be happy to discuss this with you.

Like you, I started with sulcatas and leopards in '91 and went through all the pyramiding woes. Mine also did a little better and began to smooth out once they were outside more of the time, but usually not until about 12" Its drier here. I didn't figure out the humidity thing until 2007 after countless failed attempts. You talked to Fry, while I was talking to Dr. Mader, Dr. Greek and the SD Zo keepers. I also went to all the big reptile shows and talked to every breeder, vet and "expert" I could find. None of them had the answer. With a lot of help from many sources, I figured it out myself in 2007. I'm still experimenting and trying new things. We've learned a lot, but there is still so much more to learn. Have you tried the humid method on any of your hatchlings yet? I'd love to hear your thoughts. Check this thread out. It details how I do all my incubation and baby starting. Please add to it, if you've got any other good tips: http://www.tortoiseforum.org/threads/how-to-incubate-eggs-and-start-hatchlings.124266/

Okay. Back to your topic at hand: Night temps for adults that live outside.

Like you, my first few tortoise houses were kept in the 60's. I used modified rubber made sheds with CHE's and Kane mats on thermostats. I also helped countless friends and family set up similar night boxes or dog Igloos. Like you, all my tortoises were fine. They were healthy, they ate, they bred, and all seemed good. I did it this way for years.One difference: I did not provide them with basking lights in winter. Our winters here are a little warmer than yours with 80 degree days and sunshine being common, although not this year.

Why did I change my opinion? Several things happened concurrently a few years ago:
1. I made some underground shelters for some monitor lizards and tegus. Eventually I made this one too: http://www.tortoiseforum.org/threads/daisys-new-enclosure.28662/
What I learned was that all summer long the ground temps here were 80. Actually 79-81. Didn't matter what the temps were topside, it was ALWAYS 79-81 underground. Could be 45 at night or 118 at 2pm and the temp in those 3' deep boxes stayed 80. In winter, with no heat they stay 50. Not 45. Not 60 during a warm spell. 50. All winter long. I started watching the temps in 6 areas of Africa where sulcatas occur. Their summer temps are over all hotter than ours and resembled Phoenix, AZ summer temps. Their winter temps were very close to my summer temps with daytime highs usually near 100 and night time lows dropping into the 60's. I concluded that if my summers were like their winters and my summer temps never drop below 80 underground, then their burrows over there must have similar temps, and might be even warmer than mine.
2. I met Tomas Diagne of the African Chelonian Institute. He is from Senegal and I picked his brain for hours about burrow temps and weather conditions over there. It turns out my speculation was right on.
3. I saw a study that showed seasonal ground temps all over North America. Guess what under ground temps are in my area in summer. 79. And 50 in winter. This was no surprise to me…
4. I was always concerned when we would have our cold winter spells with night temp dropping below freezing. My torts were on their heats mats and all was fine, but it scared me. A friend of mine had a young 110 pound Galpagos female. Her night box was a shoddy 3x3x3' cube of plywood and he used an oil-filled radiant heater for heat. She would rest up against it and it even touched the wood. He ran it on "high" all winter long. Obviously this is not safe, or to be recommended, but it showed me something. It was warm in that box, and his big girl was super healthy and active all winter long. This got the wheels in my head turning and I took his design ideas and fixed what I perceived were the problems. This was the result: http://www.tortoiseforum.org/threads/the-mother-of-all-tortoise-boxes.20527/
You can see my older Rubbermade night box in one of the lower pictures. I made many more night boxes and each one got better. Here is the next:
http://www.tortoiseforum.org/threads/my-best-night-box-design-yet.66867/
And finally, my most recent: http://www.tortoiseforum.org/threads/double-door-night-box.129054/

When I first finished "The Mother of All Tortoise Boxes", my thought was to give them warmer air to breath instead of just a warm mat to lay on. The results in just the first few days and weeks were astounding to me. Their winter appetites and activity levels more resembled summertime. Over the next few months, I saw a vast improvement in overall health, activity, breeding, number of clutches, appetite, growth, etc… Any way you want to measure it, they were doing BETTER when I kept them warmer. Some people have said this is "not natural" in North America. Well no, it is not. I would not keep any North American species this way. My contention is that given all of the above info, 80 degrees in the burrow at night is COMPLETELY natural for an African sulcata living in Africa, and I aim to simulate that as best I can.

I've tried different temps over the years. A little warmer, a little cooler… I find 75-80 is best for summer with our hot days here and 85-86 is best for winter when not all the days will warm up.

Now I will never contend that they can't survive cooler temps. My contention is that warmer temps are better for them and more closely simulate what wild sulcata burrows would offer them. I'm not interested in mere survival. I want optimal conditions, so my tortoises will thrive. And thrive they do.

 

[Markw84]

Thanks for the response so well thought out. That's what I was looking for. I have no direct experience in their natural habitat, and your findings are enlightening. I thought I had studied all your posts I could find, but did not see the one on your last double door night box. I used the same layout in my last two tortoise houses with the double doors and removable divider inside. At my last house I ended up with it out for the last 8 years or so as the enclosure was large enough with many overgrown plant sight barriers, that everyone got along fine.

My goal is also to have them thrive not just survive, and from your response I think I will undertake a retrofit of better floor insulation and heating in my current tortoise house.. What type heater are you using? That's my biggest challenge with Calif elect rates.

 

[Tom]

Thanks for the response so well thought out. That's what I was looking for. I have no direct experience in their natural habitat, and your findings are enlightening. I thought I had studied all your posts I could find, but did not see the one on your last double door night box. I used the same layout in my last two tortoise houses with the double doors and removable divider inside. At my last house I ended up with it out for the last 8 years or so as the enclosure was large enough with many overgrown plant sight barriers, that everyone got along fine.

My goal is also to have them thrive not just survive, and from your response I think I will undertake a retrofit of better floor insulation and heating in my current tortoise house.. What type heater are you using? That's my biggest challenge with Calif elect rates.

What I would love to see is for you to try keeping some of your tortoises consistently warmer, and leave the others as you've always kept them. With someone of your experience level and knowledge of your own long term tortoises, I would be FASCINATED to see and hear your results. Do you have more than the one tortoise house in your avatar?

Electrical usage and efficiency have always been a big factor for me. This is why I moved away from the taller boxes and never went to a shed. With my boxes only about 20" tall inside, I'm not heating a bunch of air that the tortoises will never use. When I make the boxes, I also seal every joint so there is no warm air leakage on a freezing night except right around the door. I have found the mini oil type heaters to be the most efficient for this purpose, but I don't think they will work in your super cool tortoise house very well. I only use an average of .18 cents a day over winter to heat my boxes, even with occasional below freezing night temps.

 

[Markw84]

The house is only 32" tall at the walls. I made the roof hinged to open the section over the right hand door - you can see the seams for the opening door and roof especially in my larger picture in my gallery. Brenda also really wanted it to match our house - so the stucco and 8/12 pitch. Right now the roof is insulated at the roof with insulation board and sealed at all edges with expanding foam insulation. So it's really sealed. But I think if I now add an insulated ceiling at the bottom of the trusses I made, I will only be heating an area 30" high or so. That will limit the ease of access I have now. The house is slightly bigger than your new double door box at 5 x 9 but not that much difference there.

It is my only tortoise house so I cannot do a concurrent comparison, but with my experiences and records from the last 25 years, I think I should definitely see the differences this will make over the next few years.

What do you do for humidity in your boxes? Do you worry about that outside with the adults?