What is hibernation?
Hibernation is a process that increases the chance of survival when cold temperature, a lack of food sources, or a low water supply are causing an animal to expend more energy than what it takes in. Technically, only mammals hibernate. Those that hibernate produce a substance called hibernation inducement trigger (HIT), which causes them to go into hibernation. Their body temperature lowers dramatically, and their respiratory rate and pulse also markedly decrease. While in the state of hibernation, they live off of their fat supplies. Bears are typical of species that hibernate.
In reptiles the process is more accurately called "brumation." Due to cold temperatures, the body metabolism slows down to the point where little energy is used. The reptile remains awake, but is very sluggish. In this article, we will use the terms interchangeably.
Why do some reptiles need to brumate?
For many reptiles, hibernation is necessary for breeding. The cooling period stimulates ovulation and the production of sperm.
Since reptiles are cold-blooded, they need to protect themselves from temperature extremes. In the wild, reptiles find or burrow into areas that will protect them from the severe cold.
Since they are cold-blooded, reptiles have difficulty digesting food at cool temperatures. Prior to brumation, a reptile undergoes a fast, and his digestive system empties. The cool temperature allows him to expend little energy at a time when he is not consuming any food.
Besides box turtles, what other reptiles brumate?
Reptiles from many ecosytems hibernate including desert tortoises, temperate box turtles and tortoises, aquatic turtles, and most temperate zone snakes. Turtles and tortoises that hibernate include:
- Horsfields tortoise (Testudo horsfieldii)
- Russian tortoise (T. horsfieldii)
- Spur-thighed tortoise (T. graeca)
- Marginated tortoise (T. marginata)
- Hermann's tortoise (T. hermanni)
- Desert tortoise (Gopherus agassizii)
- Gopher tortoise (G. polyphemus)
- Texas tortoise (G. berlandieri)
- Wood turtles (Clemmys insculpta)
- Spotted turtles (Clemmys guttata)
- Red-eared sliders (Trachemys scripta elegans)
- Snapping turtles
Most temperate snakes, including king snakes, milk snakes, bull snakes, rat snakes, water, and garter snakes need to hibernate.
When does my turtle need to start hibernation?
When hibernation should start and how long it will last depends upon the species of reptile. Most North American box turtles will become less active, eat less, and search for places to burrow or hide around September or October. Hibernation generally begins around mid-October.
How do I prepare my turtle for hibernation?
One of the most important things to remember is that hibernation can cause far more harm than good if it is not done correctly. Proper preparation of your turtle is key.
Medical examination - Only healthy turtles should be allowed to hibernate. While hibernating, the immune system is not functioning adequately, and any infection or other illness can turn into a disaster. At least 8 weeks prior to hibernation, your turtle should receive a complete physical examination by your veterinarian who will look for signs of illness such as:
- Low body weight
- Ocular lesions or discharge
- Difficulty breathing
- Nasal discharge
- Oral lesions
- Open-mouthed breathing
- Parasites (a fecal exam should be performed)
- Discharge from the cloaca
- Wounds or shell rot
Your veterinarian will want to know what your turtle has been eating, and how much, as well as any history of stress or signs of disease. Keep accurate records of your turtle's feeding habits and weight throughout the year so you will be able to provide as much information as possible.
If your veterinarian finds any disease process or that the turtle is underweight, lost too much weight since the spring (over 10% of his body weight), or has not been eating, the turtle should not be allowed to hibernate. Instead treat the illness, and feed the turtle until she gains sufficient weight. At that time she can enter a shorter hibernation period under strict monitoring.
Diet change - During the summer months the turtle should be fed a balanced diet that includes adequate sources of vitamin A, which can become rapidly depleted during hibernation. Include these excellent sources of vitamin A:
- Dark green leafy vegetables such as kale, mustard, collard, broccoli, and dandelions (less of spinach, beet greens, and romaine lettuce)
- Orange/yellow fruits and vegetables, such as carrots, winter squash, sweet potatoes, cantaloupe, and peaches
- Baby mice and fish
Towards the end of summer, increase the amount of fiber your turtle receives by adding additional high-fiber weeds, grasses, timothy hay and alfalfa.
Approximately 10-14 days prior to hibernation, food should be withheld. It is critical that the digestive system be empty when the turtle enters hibernation since the undigested food within the intestines can result in severe illness. Water should still be available during this time.
Hydration - Turtles should be soaked for periods of 20-30 minutes at least every 48 hours prior to hibernation by placing the turtle in a shallow container with about 3/4 inch of tepid water. This will help keep the turtle hydrated as well as encourage defecation and emptying of the digestive tract.
Weight - It is essential to accurately weigh your turtle prior to and every 2-3 weeks during hibernation. Invest in an accurate digital scale, especially if your turtle is less than 6 pounds. Obtain your turtle's weight in grams and record it, along with the date, on a chart you will maintain throughout the hibernation.
How do I prepare a place for my turtle to hibernate?
The container in which you hibernate a turtle is called a hibernaculum. You can easily make one. Use a one foot square plastic sweater box or similar storage container. Fill it 2/3 full of newspaper and moistened peat moss. When ready for hibernation, allow the turtle to burrow into the material. Drill 6 holes, 1/4 inch in diameter in the lid and attach it.
The hibernaculum should be kept at a temperature of 40-50°F in a draft-free room. The humidity in the room should not be high - if properly set up, the hibernaculum should maintain the proper humidity. Darkness is not necessary, and in fact, some natural lighting is recommended. If the turtle is too active and the temperature is within the recommended limits, the amount of light can be decreased.
How do I start the hibernation process?
When the healthy turtle has been fasted, hydrated, weighed, and the digestive tract has been cleared, move your turtle to a place at room temperature (65-68°F) for 2-3 days, then move the turtle or lower the temperature to around 60°F for another 2 days. Then, place the turtle in the hibernaculum and move it to the cool room you have selected.
How do I monitor my turtle during hibernation?
Every 2-3 weeks you will need to check your turtle for proper hydration, weight, appearance, and activity. If any problem or abnormality is found, the turtle should be rehydrated and warmed, and the hibernation process should be stopped.
Hydration - Examine the skin to determine if she is drier than normal. Also, check the substrate to determine if the turtle has urinated. If the skin is dry and/or the turtle has urinated, she should be allowed to soak in tepid water for 30-60 minutes. Dry the turtle and then replace her in the hibernaculum in the cool room. Some turtle owners will soak their turtles every 2-3 weeks even if they seem adequately hydrated.
At this time, also check the substrate for any excess moisture or mold, and replace the substrate if necessary. If the substrate appears too dry, it can be remoistened.
Weight - As a general rule, a properly hydrated turtle should not lose more than 1% of her body weight per month of hibernation.
Appearance - Examine the turtle for any discharge, breathing difficulties, or skin or shell changes. During this time the turtle should open her eyes.
Activity - Hibernating turtles should not be active. If a turtle is overactive during the time she should be hibernating, the temperature is probably too warm and the turtle is expending too much energy.
How long should my turtle hibernate?
Healthy species of turtles from the Northern and Western United States can be allowed to hibernate for 6-8 weeks. For those from the South and Southeast U.S., 4-6 weeks is usually adequate.
How do I bring my turtle out of hibernation?
When taking a turtle out of hibernation, the reverse process is used. First, the turtle is moved to 60°F for 2 days, then to room temperature, and then to the normal warm husbandry environment. The turtle should be soaked every other day, and you may start to feed the turtle 2 days after she has been at room temperature. Some turtles may not eat for several weeks, and some male turtles may not eat until after breeding.