Brumation in Snakes: What Is Normal, What Is Not, and the Checks Before You Start

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Brumation in Snakes: What Is Normal, What Is Not, and the Checks Before You Start

Brumation is the seasonal slow-down that temperate reptiles go through when days shorten and temperatures fall. In the wild it is how a corn snake or a kingsnake survives a winter with no prey and no useful basking.

In captivity it is optional for most pet snakes and essential for almost none. Keepers who breed usually cycle their animals because reproduction depends on it. A single pet corn snake that will never be bred does not need to brumate, and a snake that is put through it while carrying an infection, a parasite burden, or an undigested meal can die.

• Brumation is not hibernation. The snake is not unconscious, and it must still be able to drink and move.
• Tropical species such as ball pythons and boa constrictors do not brumate. Cooling them is harmful.
• The gut must be completely empty before cooling starts. Food left inside a cooled snake rots.
• A veterinary check and a faecal parasite screen belong before brumation, not after.
• The word brumation is regularly used to explain away a snake that is actually ill.

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Never cool a snake that still has food inside it.

Digestion is temperature dependent. A meal that has not been fully digested and passed before the temperature drops sits in a gut that can no longer process it, and it decomposes. This causes regurgitation, severe infection and death, and it is one of the most common ways brumation kills a healthy snake. The gut is confirmed empty by withholding food at normal temperatures for a period appropriate to the species and the size of the last meal, and by seeing the snake defecate before cooling begins.
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What brumation actually is

Brumation is a behavioural and physiological response to falling temperature and shortening day length. Metabolism slows, digestion effectively stops, appetite disappears, activity drops, and the animal spends long periods in a sheltered spot.

It is not the deep, sustained torpor of a hibernating mammal. A brumating snake still moves, still responds to disturbance, and still needs to drink. Water loss continues even when nothing else does, which is why an available water bowl is not optional.

It is also not a fixed calendar event. Wild snakes brumate for as long as their local conditions require. In captivity the length is chosen by the keeper, guided by species and by purpose.

The purpose matters. In many temperate species, sperm production in males and follicle development in females are linked to a cool period, and breeders cycle their animals for that reason. A pet snake kept at stable temperatures year round, with no intention of breeding, can live a long and healthy life without ever brumating.

Some keepers prefer to give a mild seasonal cool anyway on the grounds that it matches the animal's natural rhythm. That is a defensible position, and it is different from a full brumation. Either way it should be a decision rather than something that happens because the heating was turned off.

Which snakes brumate and which must not

Temperate species that naturally experience winter.

Corn snakes, kingsnakes, milk snakes, rat snakes, gopher and bull snakes, garter snakes, hognose snakes, and other colubrids from regions with a cold season. These are the animals for which brumation is biologically appropriate.

Tropical and subtropical species.

Ball pythons, boa constrictors, green tree pythons, carpet pythons and similar species do not brumate. They come from climates with no cold winter. Some, ball pythons in particular, go off food seasonally, and this is frequently and wrongly treated as brumation. Cooling a tropical snake suppresses its immune system and predisposes it to respiratory infection, which is the exact opposite of what the owner intended.

Animals that must not be cooled regardless of species.

Hatchlings and very young snakes, which have little in the way of reserves. Underweight or poorly conditioned animals. Gravid females. Any snake with mites, a respiratory infection, mouth rot, skin lesions, retained shed, a parasite burden, or any illness under investigation. Any snake that has eaten recently.

The health checks that come first

Treat this as a pre-operative assessment, because it serves the same purpose: confirming the animal can tolerate a period during which it cannot compensate.

A veterinary examination.

A reptile vet checks body condition, the mouth, the eyes and spectacles, the skin and scales, the breathing, and palpates the abdomen. Ask directly whether this animal is a suitable candidate.

A faecal parasite screen.

This is the check most often skipped and it matters more than any other. Internal parasites carry on multiplying while the host's immune response is reduced by cold. A burden that a warm, healthy snake was containing can overwhelm it during brumation, and snakes are regularly found dead or severely debilitated at the end of a cool period for exactly this reason. Screen, and treat before cooling if anything is found.

A recorded starting weight.

Weigh the snake on the same scale and write the number down. Every judgement you make during brumation depends on this figure. Agree with your vet in advance what degree of loss will end the process early.

A confirmed empty gut.

Stop feeding while the enclosure is still at normal temperature, allow enough time for the last meal to be fully digested for that species and meal size, and confirm the snake has passed it. This period is longer than owners expect and it is not negotiable.

A completed shed.

Do not begin cooling with a snake mid-cycle or with retained shed, including retained eye caps.

A clean bill on external parasites.

Check the water bowl for dark specks and wipe the snake with white paper towel. Mites during brumation are a disaster, because the snake is cool, immunosuppressed and undisturbed.

A stable, secure setup.

Somewhere the temperature can be controlled and will not swing. An unheated garage, shed or conservatory is not a controlled environment, and a cold snap that takes the temperature below the safe range for the species can be fatal.

Doing it safely, if you decide to

One. Empty the gut and confirm it.

Withhold food at normal temperatures until the last meal has been digested and passed. Then wait longer.

Two. Reduce photoperiod and temperature gradually.

Over weeks rather than days. Shorten the day length first, then bring the temperature down in stages. A sudden drop is a shock rather than a season.

Three. Reach the species-appropriate cool range and hold it.

Look up the range for your exact species from a reptile veterinary or specialist source, and measure it with a probe thermometer at the level the snake will actually be. Do not use a generic reptile figure, and do not improvise with a domestic fridge or an outbuilding.

Four. Provide water throughout, and change it.

Fresh, clean water available at all times. This is the point most brumation failures come down to.

Five. Provide a secure hide, darkness and quiet.

Minimal disturbance. The snake should have somewhere it can settle and stay settled.

Six. Do not feed.

Nothing at all while the snake is cooled. The gut cannot process it.

Seven. Check weekly, briefly.

Look at the snake, look at the water, and weigh it at intervals you have agreed in advance. Keep the disturbance short. Note the weight each time.

Eight. End it if anything goes wrong.

Marked weight loss, any respiratory sign, discharge, a prolapse, regurgitation, or an unresponsive animal all mean the brumation ends now. Warm gradually back to the normal range and contact a reptile vet.

Nine. Warm up gradually.

Reverse the process over a similar period. Restore the photoperiod and the temperature gradient in stages.

Ten. Offer water first, then a small meal.

Wait until the snake is fully back at its normal temperature range and has been active for a while before offering food, and make the first meal smaller than usual. Watch for regurgitation.

Eleven. Weigh and reassess.

Compare with the starting weight. Book a follow-up veterinary check if the snake has lost significantly, has not resumed feeding, or seems off in any way.

What normal looks like during brumation

The snake spends most of its time hidden and still, and it comes out occasionally.

It drinks. You may not see it, but the water level drops and the bowl needs changing.

It responds when disturbed. Slowly, and less than usual, but it moves, tongue-flicks and repositions itself.

Weight is broadly held. A modest reduction over the whole period is expected. A steady decline is not.

The eyes are clear, the mouth is clean and closed, breathing is silent, and the belly scales look normal.

It does not eat, and that is correct.

The routine that keeps it safe

What never to do

Never cool a snake with food in it.

Never brumate a tropical species, however convincingly it has gone off food.

Never brumate a hatchling, an underweight snake, a gravid female, or any animal that is unwell or under investigation.

Never brumate a snake with mites, retained shed, or a known parasite burden. Treat first.

Never leave a brumating snake without water.

Never use an uncontrolled space such as a garage, shed, outbuilding or conservatory, where a cold snap can take the temperature below the safe range.

Never improvise with a domestic fridge for a snake.

Never skip the weight checks because the snake should not be disturbed. A brief weekly look is far less risky than not knowing.

Never feed during brumation, and never offer a full-sized meal immediately after warming.

Never explain a deteriorating snake as brumating. If the animal is losing weight, breathing audibly, producing discharge, or unable to right itself, it is ill.

When to get help

Contact a reptile-experienced veterinarian before you begin, for a health check and a faecal parasite screen. This is the appointment that prevents most brumation losses.

Contact one urgently during or after brumation for any wheezing, clicking, bubbling or open-mouth breathing, discharge or froth at the mouth or nostrils, regurgitation, prolapse, marked weight loss, an unresponsive snake, or a snake lying out in the open and not returning to its hide.

Book a check if the snake does not resume feeding within a reasonable period after being fully warmed, or has lost substantially more weight than expected.

Bring the starting and current weights, the dates of the last meal and the last dropping, the temperature readings and how they were measured, the cooling and warming schedule you used, the species and age, and the results of any parasite screening.

The weight record and the feeding dates are what a vet will ask for first, because in this condition the history explains the animal far better than the examination does.