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Maintenance of garter snakes


Garter Snakes are generally easy maintain. I do not intend to be definitive on the subject of maintenance:- I merely aim to describe those methods that I have found helpful.

In general, given adequate conditions, garter snakes will thrive and breed.
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My preference is for wooden vivaria with glass doors. This is more for aesthetic than practical reasons. I like to be able to illuminate the cages and observe the snakes. Many other herpetologists prefer to use large plastic containers.

Glass fronted cages have the advantage of allowing better visibility than tubs, are more easily stacked, and allow front access which possibly disturbs snakes less. They are generally bigger, and if built for the purpose can be made of a suitable size for a larger number of garter snakes. They are however more likely to be escaped from, and an unexpected birth can result in escaped babies. I have on more than one occasion lost small snakes through gaps at the edge of glass doors that I would not have believed possible. Even with the experience of having had this happen before, I have still made the mistake of thinking "nothing could escape through that tiny gap!" and been proven wrong.

Increasingly I come across evidence that garter snakes kept in plastic tubs, such as sweater boxes, are less likely to breed successfully, which may indicate a degree of stress. In general garter snakes are much more active than other commonly kept colubrid snakes, and whilst most rat and king snakes are successfully bred in sweater box containers, garter snakes seem not to breed so well under these conditions. My own experience has backed this up, and a colleague in California, who is a very successful breeder, tells me that when he changed from using sweater boxes to large glass cages, his snakes began to "breed like rabbits!"

Plastic tubs have the advantages of being easier to maintain and clean, are generally more escape-proof, and are ideal for babies and smaller snakes.

I tend to use a combination of both systems. Larger snakes are kept in wooden cages with glass doors, and juveniles are kept in large plastic tubs.

The space required per animal depends on the size of the snake. Most of my cages are 48 inches by 24 by 12 (120 cm by 60 by 30). In one such cage I would house perhaps six small snakes (adult males) or three large ones (large females).

garter snake vivarium garter snake vivarium

click on image to enlarge

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Individual or collective housing?

Again I feel this is a matter for personal preference. I favour small groups of snakes kept together, some experts prefer to house individuals alone, and one colleague from Holland keeps about 100 garter snakes together in a large outdoors enclosure.

Individual housing has the advantage of being better able to monitor snakes, and recognise problems at an early stage, and in particular identify a poorly feeding snake. It enables matings to be better controlled and timed, thus enabling better prediction of when babies are due. It reduces the chance of food fights, and accidental ingestion of other snakes. It reduces the risk of spread of disease.

Group housing has the advantage of being more aesthetically pleasing. Garter snakes tend to be rather social animals (in a biological rather than anthropomorphic sense) and on occasions do interact with each other. I frequently find two or more animals kept together will hide under the same hide-spot, even though several are available. I realise this may be due to environmental reasons (e.g. temperature) but do not observe the same phenomenon in my rat snakes or hognose snakes. I have known collectors in the USA describe finding two garter snakes together in the wild more often than with other colubrids or snakes. I rarely find food-fights a problem, unless worms are used.

It is generally recommended that gravid snakes, particularly close to birthing time, should be kept alone, to prevent accidental damage to babies (or even cannibalism, which, although rare, has been recorded), and also to reduce stress to the mother, which could result in babies being retained..
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Heating and lighting

The most important issue with heating is that the snakes have a thermal gradient. According to where the snake comes from, time of year, feeding status, gravidity and even time of day, the preferred temperature of the snake varies significantly. I use thermostats connected to a heat mat under the front part of the cage, beneath the light. The thermostat is set at around 84 deg F. The cooler end of the cage is usually around 70. In particular the more southern species (marcianus, cyrtopsis, sirtalis from Florida) are usually at the hot end, especially when gravid.

If the plastic tub system is favoured, the simple method of heating is to use a heat strip under one end of the box. This does not really require a thermostat.

It is important if using heat mats or strips underneath the floor that it covers less than half of the cage space. Even low wattage mats can provide a significant heat in confined spaces, and particularly under a hide box. I have measured a temperature of 112 deg F (48) under a clay hide box over an Ultratherm heat mat. A snake unable to escape from this would quickly die. It is worth bearing in mind that a snake's natural response to heat is to burrow. If a heat mat is being used underneath a substrate in which the snake can burrow, this can result in accidental suicide!

Another important aspect of temperature is to allow for a drop in temperature at night. This is particularly important during pregnancy, as the drop in temperature at night seems to play a role in initiating parturition. Females kept at a constant warm temperature can retain their babies, with catastrophic consequences for both mother and babies. I switch off all heat and lighting at night using a timer switch. Thermostats are now available that will allow more sophisticated control, but this is probably not necessary for garter snakes.

Lighting is a controversial issue. Garter snakes will certainly survive and breed if kept with access only to room light. This has the advantage of allowing them to naturally 'key in' to day-length. However, my own experience of using plastic boxes without lights has been that breeding has often not been successful. A Californian friend tells me that when he changed from using 'sweater boxes' to larger cages with lighting, he suddenly found that the snakes 'bred like rabbits' from next to no breeding at all.

I suspect (and have no scientific evidence on which to base this) that some of the more colourful diurnal species may benefit from access to UV light, in much the same manner as many colourful lizards do. I now use artificial fluorescent strips, containing UV light, and supposedly simulating natural daylight. However, these tubes are only replaced when they 'blow', and are at the top of an 12 inch (30 cm) high cage, so the actual UV light received by the snakes is likely to be minimal.

I would add that my own observations show that T. marcianus in the wild is largely nocturnal, and it may be that no light is required by this species. They rarely seem to bask in captivity, and indeed some of my animals will only feed at night. Albino animals may also be more at risk from bright UV lights, as their retinas will be poorly protected, and their skin probably more at risk of damage.
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Cage furnishing

It is important that the snake has access to a secure hide place. I prefer to offer two or three so that the snake has a choice of temperature. I use overturned clay flower pots with a hole cut in the base, and overturned roofing slates. It is important to ensure that the drainage hole is covered as snakes can try to get through and get stuck, with fatal consequences if not detected.

Fresh drinking water at all times is essential. Snake frequently defecate in their water. I change water at least twice weekly even if apparently clean. Water bowls should be sturdy and deep enough not to evaporate quickly.

It is important to be aware that garter snakes should be kept dry. Although in the wild many live in marshy areas, in the wild they always have access to dry land, and even in marshes and ponds there are always dry patches in warm weather. A garter snake kept in moist conditions will develop skin or respiratory disease.

Some garter snakes like to climb and sturdy branches can be offered.
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Floor substrate

A variety of different substrates are available. Many keepers use newspaper or corrugated card, which is easy to maintain, and inexpensive, although less attractive, and I also find that nervous snakes do not like it, as it does not offer a good grip to the ventral scales, and so makes it hard for the snakes to move quickly.

I now tend to use either a cat litter based on compressed sawdust, or bark chips. These allow for easy 'spot cleaning', and are large enough not to be accidentally swallowed.

Newspaper or any other dry commercial bedding substance would suffice. It is probably important to avoid sand or particulate matter that might stick to the food and be accidentally ingested, although personally I have never known this cause problems.
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Cages should be cleaned when soiled. Garter snakes fed on fish will defecate frequently and profusely. They cannot be neglected to the same extent as mouse feeders. I clean my garter snakes twice weekly and my similar sized rosy boas twice monthly!
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Garter snakes as a group tend to be good feeders, and many are rather omnivorous. Many keepers favour mice, and most garter snakes either readily take mice of suitable size, or can be persuaded to.

Other common prey items are earthworms (if you use these, it is vital to know that they have come from ground in which no pesticides have been used, and to avoid the red-striped "brandlings" from compost heaps, often sold as fishing bait, which are highly acidic and possibly toxic to snakes), fish, frogs, slugs and even meat.

Keepers should be aware that there is evidence that some garter snakes are predisposed to thiamine (vitamin B1) deficiency. This is thought to occur if they are fed an exclusive diet of oily fish, which are rich in an enzyme called thiaminase. This enzyme will destroy thiamine, so even if vitamin supplement is added to the diet or drinking water, it will still be destroyed. The manifestations of this deficiency are of loss of co-ordination, head waving, balance disturbance, anorexia, weakness, and finally convulsions and death. I have known animals showing the early stages of symptoms to make a full recovery with a change of diet.

There are herpetologists who do not believe in the phenomenon of dietary-induced thiamine-deficiency in garter snakes. I do believe in it, and have had snakes die of these exact symptoms in my early days of snake-keeping in the 1970s, when the easiest (and cheapest!) diet was whitebait, a goldfish-sized fish sold for the human market. These are eaten whole (by humans and garter snakes!). They are sold frozen in packet of 1 lb (450g). The thiaminase can be destroyed by heating the fish in hot water at 180 deg F (80 deg C) for 5 mins, but this results in a very messy product.

Other fish of this thiaminase-containing type include mackerel, spratt and herring.

Another useful food is a product called 'Garter Grub' marketed by Dinosaur Nutrition (a branch of T-Rex). This is sold frozen in pre-packaged containers. It is based on whole vertebrate prey items and is nutritionally complete. There are different preparations for adults and juveniles. It is sold in user-friendly plastic packages from which individual portions can be popped out much as ice cubes from an ice-tray. Most garter snakes take to it readily. It is available in Petsmart stores, but in some rural areas or small towns (such as where I live!) it may not be widely available. For a large collection it can work out as an expensive feeding method:- a 95g container retails at about £4 (US$ 6). Two large female garters could eat this in one sitting.

Frequency of feeding depends on the food being offered, and the size of snake. I generally feed adult snakes once or twice a week, as I use a fish-based diet. I allow the snakes to eat as much as they want. Snakes fed on mice will only require feeding once a week. Babies need more frequent feeds, and for the first two months of life I usually feed them on alternate days. This provides a rapid growth.

Over-eating is rarely a problem in garter snakes, but I have had some animals, usually females, with a tendency to become obese. These animals are restricted to four food items once a week.

One word of warning - hungry snakes will often grab at anything moving when they can smell food. This can sometimes result in accidental bites being sustained, but of more concern is the risk of snakes accidentally attacking each other. I have seen this many times, and although the snakes usually realise their mistake and let go of the other snake, occasionally the snake will just keep swallowing. This is particularly common in baby snakes, and especially with worms. If two snakes grab opposite ends of a worm, the faster will sometimes just keep eating, until he has finished the snake attached to the other end. Invariably this results in the death of both snakes. It is generally a good idea to supervise feeding if snakes are housed collectively.
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Home-made garter snake food

Several years ago I decided to attempt to mass-produce food for my increasingly large collection of garter snakes. I decided that I wanted a diet that was reliably available, and based on whole prey animals, and that could be kept frozen. I live near several trout farms, and have found one that supplies me trout at a good price.

The trout are liquidised and mixed with gelatine and vitamin powder and frozen into blocks, of which a strip can be cut off from frozen.

I have used this method of feeding for three or four years now, and with the exception of my T. cyrtopsis, which are difficult feeders, all my garter snake have had this exclusive diet for that time. I have encountered no problems that I would consider related to this diet, the only unexplained deaths being of some of my albino strain of Florida blue garter snakes, which I consider to be due a genetic defect (see My Collection). Baby Florida blue and Chequered garter snakes have thrived on this diet, and two animals have grown to adult size (and have become gravid) in well under a year.

Please note that I am not advocating that other people use this diet. It has not been tried and tested for long enough to fully exclude long-term problems. I attach the details of how to make it, but accept no responsibility for problems that may occur as a result.
  1. Take 4 whole trout of approx. 8 oz each. These must be gutted in advance (as the intestines contain ingredients that prevent the mixture from setting)
  2. Cut the trout into chunks (this makes liquidising easier), or mince it if you have access to a mincer.
  3. Make the gelatine solution. I use gelatine sachets each designed to set 1 pint of water. I mix 4 of these (i.e. 1 per trout) in a small amount (about 4 fluid oz) of very hot (but not boiling) water until fully dissolved. This is quite tedious and is easier if the container containing the gelatine mixture is placed in a pan of simmering water. The less water you can use to mix the gelatine the better. Do not allow the gelatine to boil, and do not let it cool before step 6.
  4. Warm the trout chunks up gently in a microwave so they are slightly warm but not cooked (if they are too cold the gelatine will set too quickly).
  5. Liquidise (blend) the trout chunks for 2 minutes or more to ensure all bones etc are liquidised.
  6. Add the gelatine to the liquidised trout, add 4 teaspoons of vitamin powder and blend further.
  7. Spread the paste into a suitable container to form a flat layer. I use the tops of clear plastic hatchling boxes.
  8. Leave these in a cool place to set, and wrap foil or cling-film around to stop the mixture drying out.
  9. Once set it can be removed from the container (it should be a semi-solid strip by now) and frozen. I find it helps to cut grooves along it before freezing it, and then you can simply snap off a strip from frozen as required.
  10. When feeding it to snakes, it is easier to cut whilst still frozen, before it goes soft. It is best to put it at the cool end of the cage as it does tend to go soft when warm.
  11. It does take trial and error to get the mixture of gelatine to trout right. These quantities work well for me.

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Cat food
For the last few years I have increasingly used commercial cat food for most of my adult and sub-adult snakes. This appears to have been successful, and most of the snakes have taken readily to it, and have appeared healthy and have bred successfully. I was given this 'tip' by a garter snake enthusiast in Liverpool who has used the food for years. It is worth experimenthing with different brands of food, and the fishier varieties tend to be better tolerated. My present food is Whiskas 'Oh so fishy' which is available from Tescos. In the past I found Asda's 'Tiger seafood selection' better, and to have a higher fish content, but I have no local source for that. For smaller snakes the cat food can be cut into smaller pieces, but I find that most babies do not take readily to it. I therefore feed smaller snakes on strips of my home made food, and during their second year find that most will readily switch to cat food. The main advantage of the cat food is that it is less expensive both financially, but more importantly in terms of time and effort spent making my home made food.


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Hibernation is helpful, if not essential, to the successful breeding of garter snakes. The duration and temperature of hibernation varies according to species, and different breeders have their own ideas. It seems that more northerly species will not breed without a prior hibernation, and mating takes effect immediately after hibernation, often within hours. More southerly species may breed without hibernation, and if they are cooled it may be some weeks before mating occurs. I tend to keep my garters at about 50 to 60 deg F (10 - 15 deg C) for 8 to 12 weeks from early December. Sometimes the snakes know best, and if they go off their food late in the year then they are cooled sooner. Most breeders suggest separating males and females during hibernation, but I can see little need for this, and frequently hibernate animals in mixed sex groups.

More northern species may require a colder hibernation, and some breeders will hibernate their snakes in a domestic refrigerator.

Prior to hibernation it is important to ensure that the snakes have been starved for two weeks. This prevents undigested food from decomposing during hibernation.

After hibernation there are different ideas about how quickly to warm up the animals. I have always followed the perceived wisdom of a gradual increase in temperature over a week or so, and usually find that the animals quickly aim for any hot spots. Often they will refuse food until after their first shed, although some feed almost immediately. Philippe Blais MD, who very successfully breeds Crimson garter snakes in Quebec, warms up his animals with just a 24 hour transition period to normal temperature ("Flame Garters - A Variation on an Old Theme" - the Vivarium Vol 9 No 6).
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Sexing snakes

Snakes are sexed by one of three methods:-


A, B & C - Female tail; ventral and lateral views. The tail base enlargement noticeable in some females (see B) appear to be male glands, but note that the tail tapers rapidly

D & E - Male tail; ventral and lateral views. Tail base is thick, and this thickness extends for some distance beyond the vent.

Illustration and description by kind permission of Mr Robert J. Riches, author of 'Breeding Snakes in Captivity', 1976

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If you have got everything else right, then this pretty well happens on its own!

Although such a comment may cause offence to some excellent and reputable herpetologists, it is not far from the truth! Both myself and Mr Bob Riches have experience of Florida blue and Chequered garters breeding repeatedly without prior hibernation. Indeed I have had two female juvenile chequered garters have healthy litters at less than 11 months of age, with no prior cooling period. This was accidental, and they mated with their brother with whom they were being housed.

Again there are varying opinions as to how best to achieve a successful mating. It is certainly worth introducing the male to the female immediately after hibernation. If that is not successful, then frequent reintroductions should be tried, particularly after either sex has sloughed. My own approach is rather unscientific:- I just leave them together and let them get on with it. Those with more voyeuristic tendencies are advised to avoid this technique as not uncommonly the female(s) become gravid without mating having been observed.

Mating is along the usual colubrid line of courtship. Successful mating results in a visible seminal plug or a gaping of the female's cloaca, although I have known successful matings where this was not identifiable.

It is usually a month or so after mating before pregnancy becomes obvious. A lumpiness can be felt in the ventral aspect of the female's mid-body. This is best felt when her muscles are relaxed by letting her gently run through the hands. As the pregnancy progresses the swelling becomes more pronounced and moves caudally (tailwards!). She often stops feeding in the second half of her pregnancy, after initially eating voraciously.

Birth occurs typically 90 to 100 days after mating. The female should be alone, in an escape-proof (for babies!) cage, and there should be plenty of cover for the babies to prevent accidental injury from the mother. Some breeders advocate a 'nesting box' with damp sphagnum moss inside - this may stimulate the mother into giving birth, and also assists the young with their first slough. The young are immediately independent and many start to feed within a day or two. Sloughing can be from day 1 to day 10.

The babies are cared for in much the same way as adults. I usually find tiny strips of my home made food are taken readily, but some require scenting with worms for the first few feeds. One or two stubborn babies refuse it for some weeks or months, and despite being fed worms with the same frequency, their growth is significantly less than their siblings.
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