Brumation is more or less the reptile equivalent of mammalian hibernation. Like mammals, reptiles brumate to survive long periods of cold temperatures and scarce food. However, because they’re cold-blooded, reptiles can slow their metabolism down much more than mammals can, sleeping for weeks on end without losing a significant amount of body fat.
Red-eared sliders and other pond sliders are particularly good at brumating. Not only can they survive frigid temperatures, but they can also survive oxygen deprivation. According to Complete suppression of protein synthesis during anoxia with no post-anoxia protein synthesis debt in the red-eared slider turtle Trachemys scripta elegans, red eared sliders are capable of surviving up to five days without oxygen at 61-64°F (16-18°C), and they can go 4-5 MONTHS without oxygen at 37°F (3°C)! This is supported by Donald C. Jackson’s findings recorded in his book, Life in a Shell, where he writes that 3°C seems to be the optimal temperature for prolonged anoxia in another North American species, Chrysemys picta. This is made possible by switching their cells from aerobic to anaerobic cellular respiration, dropping metabolic rate to barely a trickle. Calcium stored in the turtle’s shell play an important role in buffering the lactic acid produced as a byproduct of anaerobic metabolism.
In the wild, red-eared sliders become inactive around October. Around this time, they will burrow into the bottom of a pond or shallow lake, or occasionally underground or in a hollow tree stump. Throughout the winter they remain motionless in a state somewhere between sleep and death — not eating or defecating, and barely even breathing. As temperatures rise in early March-end of April, they wake up and go back to business as usual.
Some experts speculate that brumation is not just a survival mechanism. For species that brumate on a regular basis, brumation may be an integral part of long-term health. So brumation should be encouraged in your pet pond slider. That being said, many experts recommend that turtles younger than 3-4 years should not be allowed to brumate. In theory they can survive brumation (and many do every year), but delaying brumation maximizes your turtle’s likelihood of survival in the early years, and doesn’t seem to harm the turtle in the long run.
- Loss of appetite around October
- Reduced activity
Note that while many turtles will attempt to brumate on their own schedule, some turtles do not. If your turtle’s behavior doesn’t change in the fall, there is no need to force your turtle to brumate — in fact, this can be very dangerous if you don’t know what you’re doing.
Preparing Your Red-Eared Slider for Brumation
You don’t need to worry about your turtle’s fat stores, but you do need to think about calcium, since it plays a major role in helping your turtle survive for long periods of time without oxygen. Offering a little extra cuttlebone or other high-calcium treats like whole prey may be helpful.
1-2 Months Before Brumation
About a month before brumation, take your turtle to the vet for a general examination and fecal check for parasites. To survive brumation, turtles must have enough fat stores and be in good health. Sick, recovering, or underweight turtles should not brumate.
3 Weeks Before Brumation
When your turtle starts eating less in the fall, that’s the signal that your turtle is preparing for brumation. At this point, stop offering food.
1 Week Before Brumation
Now that your turtle’s digestive tract has been cleared out, remove/turn off all heat sources and let your turtle get used to being at room temperature.
At this point, your turtle will likely become quite lethargic. Place your turtle in a ventilated brumation box (ex: plastic shoebox with holes drilled into the sides) lined with slightly moist soil and leaf litter. Place your turtle in a mini-fridge set to 37-41°F (3-5°C). Alternatively, you can use an upright mini freezer controlled via thermostat to achieve this temperature. Although red-eared sliders can go a good while without oxygen at those temperatures, it’s still a good idea to open the door of the fridge/freezer once a week to check on your turtle.
If you live in an area where winter weather consistently stays between 35-60°F (2-15°C), you have the option of allowing your turtle to brumate outdoors (in a protected box, of course). If your turtle lives in an outdoor pond deep enough that it won’t freeze all the way down to the bottom (aim for at least 6″ of liquid in the dead of winter), you can simply let them brumate in their pond!
Note that temperatures below 35°F/2°C can cause the turtle to start to freeze, and temperatures above 60°F/15°C can cause your turtle to experience a “false brumation,” which is when they are too cold to move around and eat, but too warm to adequately reduce their metabolism. This can cause a turtle to slowly starve to death!
If you’re using the mini fridge/freezer approach, 38-41°F/3-5°C is going to be the ideal temperature for red-eared sliders to brumate.
During brumation, your turtle may lose 1% of its body weight. Weight loss greater than this can indicate that something’s wrong, so it’s best practice to weigh your turtle every 2-4 weeks with a digital kitchen scale to track their weight. This is the best way to monitor your turtle’s health during brumation, and it doesn’t seem to have any adverse effects on the brumation process. If excessive weight loss begins to occur, take your turtle to the vet immediately!
During these weigh-ins, you can soak your turtle for a little while before putting them back in their box. This helps prevent dehydration. Shallow water (no deeper than your turtle’s mouth) at room temperature for 2 hours is plenty.
Turtles which are brumating outdoors in a pond should not be disturbed.
Young and/or particularly small turtles should not brumate for more than 10 weeks. Normal-sized adults can brumate for up to 14 weeks.
At the end of this time period, return your turtle to its tank at room temperature. Heat sources should be left off for now, although it’s good to let your UVB and daylight lamps cycle as usual — about 12 hours on/12 hours off.
1 Week After Brumation:
Turn your turtle’s heat sources back on.
2 Weeks After Brumation:
Your turtle should be eating again, likely with increased appetite and activity.
Brumation should not attempted without the assistance of an experienced reptile veterinarian, especially if this is your first time! Brumation is beneficial, but it’s also dangerous, too. Don’t be afraid to call your vet when you’re feeling unsure. You may want to ask them if they provide brumation services, as many exotic veterinarians offer this on demand.
Fraser, K. P. P., Houlinhan, D. F., Lutz, P. L., Leone-Kabler, S., Manuel, L., & Brechin, J. G. (2001). Complete suppression of protein synthesis during anoxia with no post-anoxia protein synthesis debt in the red-eared slider turtle Trachemys scripta elegans. Journal of Experimental Biology.
Jackson, D. C. (2013). Life in a Shell. Harvard University Press.
Muryn, R. (2018, July). Health and Hibernation of Freshwater Turtles. ResearchGate. https://www.researchgate.net/publication/326400528_Health_and_Hibernation_of_Freshwater_Turtles
Navarrette, DVM, A. (n.d.). Brumation in Turtles and Tortoises. TexVetPets.org. https://www.texvetpets.org/article/brumation-in-turtles-and-tortoises/
Morris, P. (2002). Hibernation Guidelines for Turtles and Tortoises. Melissa Kaplan’s Herp Care Collection. http://www.anapsid.org/hibernation.html