Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 30, Number 10;   October, 2003

Box Turtle Hibernation

by Roger J Klingenberg, DVM

Pre-Hibernation Evaluation
When mature box turtles are ready to hibernate, they stop eating, become lethargic and attempt to burrow or hide. This point in time varies with the locale and local population of turtles. In general, this begins in mid-September to mid-October but could commence later in the fall and winter. It is essential that box turtles are healthy prior to hibernation. A pre-hibernation examination, including an accurate body weight, should be the first step toward the winter nap. The turtle is weighed on a gram scale so its weight can be monitored every 2-3 weeks during the course of hibernation.

Clinical Signs of a Box Turtle Too Debilitated to Hibernate
Low body weight Weakness, lethargy Ocular lesions
Dyspnea
Nasal discharge Open-mouthed breathing Anorexia
Dehydration
Malnutrition
Physical and mental "burn out"

No Hibernation Required?
Immature box turtles may continue normal activity and feeding behavior throughout the winter until they are several years of age. It is not imperative that healthy immature turtles are hibernated as long as they continue to thrive. However, if behavioral changes characteristic of pre-hibernation are exhibited, even very late into the winter, the turtle should be hibernated, even if only for a brief time.

Adults that have recently recovered from moderate to critical illness may avoid hibernation that season.

Turtles from the southeast US are accustomed to a shorter cool season and may continue to exhibit normal behavior into the fall and winter. In these cases, it is prudent to either delay or skip hibernation altogether based on the continued normal behavior of the turtle. If in doubt, hibernation is suggested if health issues do not exist.

Food withdrawal
In anticipation of hibernation, turtles should be maintained under normal husbandry conditions with food withheld for 10-14 days. It is essential for the gastrointestinal tract to be emptied before cooling to prevent infections secondary to the retention of undigested food.

Soaking
Turtles are soaked at least every 48 hours prior to hibernation, which provides hydration and encourages emptying of the GI tract. A soaking consists of a 20-30 minute period of letting the turtle lounge in a container (not the family's kitchen sink) with about ¾ inch of tepid water. After clearing the GI tract, the turtles are kept at room temperature (65°F) for 2-3 days, 60°F (possibly a basement) for another 2 days, then placed in their hibernaculums and moved to a cool room maintained at 45-50°F.

Hibernation Procedure
One example of an appro.priate hibernaculum is a plastic sweater box (e.g., Rubbermaid ) approximately 12" x 12" x 12" with, six small holes drilled in the lid. The box is filled two-thirds full with a mixture of shredded newspaper and peat moss that has been moistened with water (but does not drip when compressed in the hand). The turtle will readily burrow into this mixture, which will help prevent dehydration. Although the light cycle is one of the subtle clues reptiles use to recognize seasonal changes, turtles hibernated in the dark do just as well as those exposed to a light cycle..The two most important factors in hibernating turtles are maintaining hydration and monitoring them. Every 2-3 weeks, the turtles are removed from the hibernaculum and warmed to room temperature for 2 hours during which time they are exam.ined, weighed and soaked. If any health concern is encountered, such as nasal discharge or failure to open the eyes, the turtle is warmed up and the health issue is addressed. It is typical for the turtle to lose only 1-2% body weight. A weight loss of 10% or more may necessitate the removal from hibernation, although hydration will often quickly correct acute weight losses. Again, the turtles are allowed to soak for 20-30 minutes at a time in tepid water. The substrate is checked for moisture content and remoistened if needed. The turtles being returned to hibernation are taken directly from soaking at room temperature to the cool room with no deleterious effects.

Ending Hibernation
Turtles originating from the Northeast, Midwest and western US ideally should be hibernated for 3-4 months, although a 6- to 8.week hibernation period is usually adequate. Turtles that originate from the South and southeast require shorter periods of cooling, often as short as 4- 6 weeks. If the turtle has been checked every 2-3 weeks and is thriving with stable body weight, there is no rush to stop hibernation. Once it is determined that hibernation will cease, the turtle is moved to 60°F for 2 days, then to 65°F, and then to room temperature. The turtle is soaked every other day and feeding is resumed 2 days after acclimating to the warm room under normal husbandry conditions.