Reptile Brumation: When and How to Do It Safely

In the hobby "hibernation" and "brumation" are used interchangeably, although the second term is the correct one. Mammals hibernate — they lower their metabolism while still regulating body temperature. Reptiles brumate: their metabolism slows with the ambient temperature because they have nothing to sustain it with. The practical difference matters, because a brumating reptile is not deeply asleep. It moves, it drinks, and at too high a temperature it burns reserves and comes out of winter thin.

Why brumate at all

• Breeding. In most temperate species (corn snakes, milk snakes, tortoises, leopard geckos) a cool period synchronises spermatogenesis in males and follicle development in females. Without it males may be infertile and females may not ovulate.
• Biological rhythm. An annual temperature and photoperiod cycle shapes appetite, activity and growth. An animal kept at a constant 28 °C for ten years ages faster.
• Recovery. Weeks without digestion and at low metabolism are a genuine rest period.

Tropical species — ball pythons, crested geckos, warm-water turtles — do not brumate. At most they get a mild night drop of 2–3 °C and a shorter photoperiod, often called cycling.

When brumation must not be attempted

• An underweight animal. Anything that has lost weight in the last three months, or shows hollows beside the spine, stays warm.
• First-year juveniles. Many breeders only brumate from the second or third season.
• Signs of respiratory infection — wheezing, mucus bubbles, open-mouth breathing. Cold shuts down immunity.
• Internal parasites. A faecal test before the first brumation is worth the money.
• Recent surgery, injury or an active shed cycle.

Preparation

Fasting

The animal must enter brumation with a completely empty gut. Food left in the intestine at 12 °C does not digest — it rots, and that ends in sepsis.

• Medium snake: last meal 14–21 days before cooling, with full temperatures maintained throughout.
• Lizard (leopard gecko): 10–14 days.
• Tortoise: 3–6 weeks with daily baths.

Gradual cooling

1. Shorten the photoperiod by about an hour per week down to eight hours.
2. Switch off spot heating and let room temperature take over.
3. Drop the temperature 2–3 °C every few days until you reach the target.

Conditions during brumation

• Temperature: 10–16 °C for most temperate species; European tortoises are usually kept at 4–8 °C. Stability matters more than the exact figure.
• Darkness or very dim diffuse light.
• Water available at all times — brumating reptiles drink, and dehydration causes more losses than cold.
• Ventilation. Sealed containers with no air exchange are dangerous.
• Duration: 6–12 weeks. Under six weeks rarely triggers the breeding response; over twelve wastes reserves.

Monitoring

Check the animal once a week, briefly, and change the water. Weigh it every fortnight and log the number.

Acceptable loss across the whole period is 7–10 % of starting mass. Losing more than 1 % per week means the temperature is too high or the animal is dehydrated — end the brumation.

Also end it immediately on seeing nasal mucus, sunken eyes, complete unresponsiveness or any cloacal discharge.

Waking up

Warm up as gradually as you cooled, over 7–14 days. Offer the first, smaller-than-usual meal only after the animal has had full temperatures for four or five days. In many species the first post-brumation shed follows within two to three weeks, and females begin follicle development.

Typical figures