Here’s an interesting observation that I made during this year’s DHL hibernation that I’d like to share.

I’ve been hibernating my 3 CB DHL’s in about 3” of fine grade Calci-Sand in a single screen top aquarium measuring approximately 24”L x 12”D x 8”H. When they first started digging head in last fall I noticed that the instability of the sand was making their attempts to dig deep pretty much ineffective. As fast as they could dig a hole it was being covered up by the surrounding loose sand. They were spending a lot of valuable energy needed for hibernation and getting nothing for it, so to help them out I moved them into a secondary tank and then added enough water (couple of cups) to thoroughly moisten about 50% of the hibernation tank’s sand. I then put the heat lamps back on the sand and let it cook for a day or two. Once the surface layer was dry and the sand beneath it was clumpy, I re-introduced the lizards. Immediately they started tunneling into only the moistened side of the tank. By the next morning all 3 DHL’s were completely out of site and the sand looked pretty smooth with no significant signs of digging. I should mention that while they are in hibernation I maintain a 40 watt incandescent spot light for surface heat (over the moistened side) and a florescent bulb for UVA lighting. These lights are on for 2 hours in the morning and 3 hours in the evening. The rest of the time ambient light is the primary light source. During the winter, the temperature inside the house is generally maintained at ~ 68F at night, ~ 65 evenings and up to 70F during the days depending on the ambient temperature.

Over the next couple of weeks I would see one or two of them now and again, but they generally would disappear within a day or two. Then, after about 3 or 4 weeks of not seeing any of them I began to get a little nervous, so during the Christmas break I dug them up to make sure they were OK. To my relief they all were found to be quite healthy, showing ample weight, quite alert and even started eating within a couple of minutes of being dug up.

The really interesting thing I noticed at this time was that each of the DHL’s had created something of a little den in which to hibernate. The dens seemed to be oval in nature, as if little air bubbles had been trapped in the sand and just large enough for the lizards to move around in.

I realized then that this was most likely normal behavior and I was probably interrupting a natural event, so I moved all of the lizards into the second tank while I “reset” the hibernation tank as mentioned before. Over the next couple of days I maintained the DHL’s in the mid 80’s using over head lighting. I hydrated each of them every day by soaking them in ¼ inch of warm water for about 15-20 minutes and fed them as much as they wanted to eat, which was not all that much. When the hibernation tank was ready, I reintroduced them back into the hibernation tank. They stayed active for a couple of days and then one my one they disappeared.

At about the 1 month point, the female of the group emerged a little leaner then when she went under. Since she didn’t seem to want to go back under I started her back on my standard feeding/watering regiment and upped the wattage of the heat lamp to 60Watts. She’s been active since emerging in February and has slowly put her weight back on. Last week I decided it was time to check in on the boys so I dug them up. Again I found each of them in a cave, which to my surprised was still slightly moist to the touch. Both came out a little angry this time as they started hissing at me as soon as they appeared. Their weight looked down a bit, but not as much as was the case for the female. They both are in good health and started eating as soon as they warmed up. I’ve since hydrated them twice and now they are no longer attempting to dig deep and are aggressively feeding. It appears hibernation is over for this group. Timing is just about right as it is starting to warm up here in So. CA.

I’m wondering, have any of you observed your DHL’s to create these dens?

Thanks,
Roger

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