First thing to do is be to check that he is not wheezing and/or that there is no mucus or bubbles coming from his nose. Also keep an eye out that he’s not opening his mouth for a long time or yawning frequently. Those are the red flags of respiratory disease. If you notice those things you need to get to a vet ASAP. Respiratory disease is often fatal and definitely not something to mess around with.
That said, it doesn’t sound like the case here. Since he spends half his time outside, I’m wondering if temperatures in your area have changed. If it has been cooler outside that would definitely cause lethargy. Depending on his size, even a smallish temperature change can affect his energy level. The fact that a warm soak perked him up makes me think thats the case. Larger torts can tolerate smaller temperature changes better. Direct sunlight outside is natures basking lamp but, again, smaller tortoises get cooler faster. Regardless of size you want to be extra careful about the outside temperature during the day.
My guess is temperature is the issue here or maybe a little dehydrated. I suggest checking the outdoor temperature. Keeping him indoors (under day-temp regulated lights) during the morning/evening, as well as at night, might be a good bet if its still too cold. Also try adding a few more warm soaks to his schedule for a while. That can help with both temperature issues and with hydration.
Try doing that and, of course, keep an eye on him. Hopefully he will snap out of it in a few days. Tortoises have off days just like us and sometimes weather conditions (rain impending etc) can make them want to go back to bed too (just like me hah) so keep that in mind.
I hope this helps! Feel free to ask more questions and send an update on how he’s doing (and send pictures!)
Quick temperature info for Sulcata Tortoises:
- As with all torts, UVB/UVA is a must.
- 90-5 degree basking area available with cooler temps around 70-5.
- Night temps can get down to then 60s but not much cooler, heat pads are no.
As always I’m not a vet nor have I personally cared for a Sulcata. All my info comes from reading, researching, and collecting info from others first hand experiences as owners/rescuers. I’m in no way a replacement for the advice of a vet.