Friday, December 11, 2009

The great heating debate

Now that the cold weather is here (at least here in New Mexico, with days in the 40s and nights in the upper 20s), sulcata owners are debating about the best way to keep our torts from freezing.

There was an interesting set of posts from a sulcata-related email list recently that got me thinking that I need to post on this topic.

In a thread entitled "getting winter ready" on the Sulcata list at Yahoo Groups, someone wrote:

Just a reminder to be very careful with heat from below the tortoise - their natural instinct is to burrow deeper to escape heat and cool off, they will not understand why the ground is hot and may get hurt. Heat from above is a much more natural solution, and lets the animal regulate their own body temp.

I have to say that I disagree with this person's line of thinking. We have four large sulcata tortoises that are spending significant chunks of time this winter in their heated shelter. They are kept on Stanfield Heat Mats, which are the sole source of heating in their shelter. Our torts don't dig on these mats; they simply flop on the mats when the air temps drop at night.

During the daytime, if they cannot go outdoors, our torts simply find spots off the pads to rest. The pads do not completely cover the floor of the tortoise shelter, so there are spots where they can rest off the heat.

I am very hesitant to use or recommend overhead heat lamps or ceramic heat emitters with tortoises, for a few significant reasons:

1. Tortoises can easily get burned from overhead heat lamps or ceramic heaters. They may not feel that they are getting burned, especially if they haven't gotten warm enough to be really responsive to their surroundings.

As an example: Have you ever stood in front of a fireplace for a while? You'll notice that the backs of your legs get somewhat warm, so you may scootch back a bit, to get closer to the fire. While you're doing this, it doesn't occur to you that your pants legs are closer to the fire and they have less mass than your legs. The pants legs heat up very quickly -- just try pulling the backs of your pants legs to your legs and you'll see what I mean. Your pants legs can be hot enough to burn you.

Burned scutes may allow fungal diseases to infect the shell. One tortoise that we delivered to a rescue person in Tucson had completely lost the scutes on one side of his shell. It turned out to be a long-term fungal infection that was difficult and expensive to treat. I think the tortoise was burned on that side (maybe too close to the wood-burning stove that his original owners used as heat in their home?), and that the burn provided an avenue for the fungal infection to take hold.

2. The tortoises' vital organs are located nearer to the plastron (bottom shell) than the top shell. That means most of the torts' mass would be closer to the heat source if you use a heat mat. The tortoise will heat up more efficiently and more completely. The heart will be able to move heated blood throughout the body, keeping the tortoise's overall temperature warmer. (This is why you're told to keep your core warm during cold-weather outdoor activities: if your core is warm, it warms the rest of your body and keeps you from shivering and getting hypothermia.)

3. The risk of fire is greatly lessened by using heat mats. If you put grass hay into the tort's shelter for food, there is definite possibility that the hay could touch the hot bulb of a lamp or heat emitter. A rambunctious bored tortoise can also knock over the heat lamp if it's not suspended safely.

Summary: we really recommend heat mats for sulcata tortoises' indoor shelters to provide direct heat to the tortoises.

A second person posted in this same thread:

I too have been busy getting them ready for the winter. I built a big wooden house for their pen outside to fit their 5'x 1' heating board/pad. We do have the occasional cold snap here in Orlando. I checked the heating pad at the end of the day and it was pretty hot. It doesn't cover the entire bottom of the house so they can get off it if they need to. But it kinda scared me bc it didn't do that last year. Is there something that I can plug it into that can regulate how hot it gets?

If you use heat mats for your tortoises, you absolutely HAVE to get a controller mechanism. Just plugging the pads into an outlet is not safe, because 100 percent of the power goes directly to the heating mat and that causes the surface temperature of the mat to reach unsafe levels.

You need to purchase a rheostat, which controls the amount of power going to the mat. Osborne Industries sells a couple of different types of rheostat to control heat mats. Click here to see the controllers sold by Osborne Industries. (Note that we are not employed by Osborne, just satisfied customers.)

We have two pads, so we're using the Power Control F911. There are two outlets on the Control, so we plug a pad into each one. Then we plug the Control into the wall outlet. Our Control is set to 4 (but we bump it up to 5 if it's going to be a really cold night).

If you have only one pad to control, you may want to use the NEW Single Heat Pad Control F300. It has a dial control like the F911 we're using.

If you have a whole bunch of torts and a whole bunch of heat mats to control, you'll need to use the Automatic Regulator F920A.

Whichever one you buy, be aware that the Controller is NOT a thermostat. It doesn't respond to air temperatures like your house thermostat. What you need to do is to monitor the mat surface temperature with a thermometer, and then adjust the Control upward or downward as necessary to keep the mat surface at about 85 to 90 degrees max.

That means -- you guessed it -- that you have to buy yet another piece of equipment. What you need is called an "infrared temperature sensor" or temperature gun. These are thermometers that shoot an invisible infrared beam at a surface, then measure the reflected beam's temperature. You may want to check auto parts stores and home improvement stores to see what they offer, or you can type "Infrared temperature sensor" into Google and see what you get. Or you can go to the website and get a small, affordable heat sensor. We have both the PE-1 and PE-2 and both work well. The PE-1 is used to monitor my fish and aquatic turtle tanks, and the PE-2 to monitor the tortoise heat mats and box turtle enclosures.

So, to summarize:

1.  Heat mats good; heat emitters or bulbs bad
2.  Heat mats require a controller unit to keep them from getting too hot
3.  To monitor your heat mats' temperatures, invest in a temp gun.

Onwards and upwards, folks.