You've seen them probably, the grass rustlers along the edges of lakes, rivers, wetlands, etc. or even sneaking around in the foliage of your garden if you should be so lucky. Often, they're the first snake people get acquainted with, and unsurprisingly as such are a group rife with rumors, old wive's tales, and inaccurate names and descriptions. Here at Carlton Carnivores, I work with a very special pair, and with them hope to shed a little light on these ever so familiar animals.
Before we get to them though, a broader intro: garter snakes are members of the genus Thamnophis, a group of Natricine colubrids not too distantly related to the true water snakes (Nerodia) and the European grass snake group (Natrix) among many others. This subfamily of snakes are marked out by their typically aquatic nature, some species even roaming tidal bays and saltwater shorelines, typically heavily keeled scales to assist in their moving through this fluid environment and grasp the slippery prey found therein, and perhaps most notably their live-bearing nature; these snakes give birth to fully-formed babies rather than lay eggs.
Garter snakes specifically are a uniquely North American group, found from Mexico all the way to even edging above the Arctic Circle in Canada (with the red-sided garter, T. sirtalis parietalis), and are named because they resemble the old-time striped garter belts once used by gentlemen to hold up their socks. Erroneously, they are often called "garden" snakes (as they commonly eke out a living in people's moist back yards), "garder," "guarder," and other odd variations of their title. A couple of the more slender species are also referred to as ribbon snakes. Once considered (and still thought so by many) to be nonvenomous too, much research in the past several years have revealed that they are a rear-fanged venomous group, though on the whole a bite even from a big garter is hardly a worry; the venom is mild, and designed to stun amphibians and fish or worms, rather than trouble large mammals (in other words, unless you're allergic, a slight swelling for a short period is the most that could occur, and most people don't react at all). Some species also classify as poisonous too, pulling the toxins of food animals such as newts and toads into their own tissues to further ward off predators; some garters of the Pacific Northwest could be deadly if eaten.
Most garters are thought of as relatively small creatures; indeed, the average size of most of the species encountered across the US, Mexico, and Canada average at less than 2 1/2 feet in total length, specimens exceeding 3 feet long considered giants. However, a couple of species are significant exceptions, and my lovely pair happen to belong to one of them:
The largest species of garter is T. gigas, the Giant Garter of central California whose female members can push to nearly 5 1/2 feet in length (bigger than many corn snakes!). Cymus and Maya belong to a subspecies of the runner-up, the Mexican Garter (T. eques). The Mexican garter contains at least ten different subspecies ranging from southern new Mexico and Arizona south at least to Oaxaca, most of the subspecies restricted to large individual lake basins throughout the center of the country. This particular subspecies is the Lake Chapala Garter (T. e. obscurus), endemic to the lake of its name and very nearby waterways located south of Guadalajara and west of Mexico City. This subspecies and at least one other (scotti) contend for the largest of the group, with the females capable of pushing upwards and over 4 feet long and potentially reaching 5 feet in length (though the current record is officially just over the 4 foot mark for this subspecies). Their score for potentially largest garter overall also comes not only from length, but also overall girth; unlike ribbon snakes or the oft-familiar common and plains garters, these are not slender animals once they are full grown, and even the more slender males can put on some heft.
While some garter snakes are rather terrestrial, this is one species that is rarely ever found away from water, and may spend most of its life in the wild swimming (Cymus is displaying this trait more than Maya, the latter of which seems to prefer just lazing about on top of her hide boxes but the former is in the water bowl every day). Lake Chapala is not a significantly deep lake, but it is immense in its surface area, the largest land-locked lake in Mexico at nearly 50 miles long and 12 across; the snakes inhabit most of the shoreline (where there is not extensive human development and pollution, of which unfortunately there is already a great deal) as well as small islands and any partially submerged vegetation within the lake itself that might give them a basking spot. From here they make forays into and around the water, hunting fish, frogs, worms, and on the shore possibly small rodents; if it's small enough, they'll go after it. Garters don't constrict their prey either, preferring to use their mild venom to help stun the animal and then eating it whole and alive (or sometimes already dead; garters are one of the snakes known, and I've seen it in person, to try and eat carrion, even if it's several days dead already).
Chapala garters are almost instantly recognizable compared to any other garter species, not only by their size but also by their coloration; while sporting both lateral and dorsal stripes and possibly checkered spots along their sides when young like many other species and subspecies, as they age these snakes tend to lose the checkering and dorsal stripe, in favor of a solid rich to deep bronzy brown coloration in the background, and the stripes fade from white to a range of hues between oceanic green to true, almost sapphire blue. Blue pigmentation is extremely uncommon in the natural world, in animals especially, and while it appears in varying amounts in other garter snakes too few possess such a rich, darker variation as a diagnostic trait. Not only are the lateral stripes blue, but so is the ventral surface; or, at least most of it, as the underside of their chin and under their tail retain the more juvenile yellowish color (which is quite a contrast). Between the stripes and the belly the bronze ground color becomes the brightest and most metallic as well.
As far south as Lake Chapala sits, seasons are not extreme here, so the short "winter" period the region experiences is often only moderately cool (a few days may drop to near freezing but most remain mild); however, it's enough of a seasonal change to be an important trigger to the garter snake's breeding cycle. They often go off of food at this time of year, holding off until warmer spring weather returns at which point they resume feeding with gusto. And by gusto, I mean that both of these goofballs have been known to fly out of their tub when they realize food is present, all other objects in the area at potential risk of being nibbled before they figure out where the food is; wild animals are no less voracious in their feeding. It is at this time (typically around February) that females begin releasing pheremones to signal the males of their readiness; as I've alluded to already, the females are the larger sex in garters, and notably so in this species, developing broader heads and necks, girthier bodies, and tend to be at least a foot longer than males of a similar age, 3-4 feet vs. 2-3; though like many other colubrids it is often possible to sex these snakes by looking at the tail (males must house their reproductive organs in the base, so they have longer and thicker tails than females), it is not unknown in garters for some males to present somewhat shorter tails or females to develop thickened bases (as is the case with mine, slightly), and so these other size differences are often useful for ensuring telling between the two.
Males often forget entirely about food when they encounter these pheremones, and go into full-drive breeding mode until the job is done and females stop being receptive. From this point on, feeding resumes as normal and females pack on as much weight as they can while their young develop over a period of 3-4 months. An adult female can then give live birth to as many as 40 young, babies that are large for a garter at 8-12 inches in length and ready to start feeding almost immediately. In the wild this period is often between late May and early June, thus these garters may reproduce twice in a year as they'll breed again shortly after and give birth around October. As a species rather in the middle of the food chain, this is important; there are plenty of large fish, wading birds, or predatory mammals that will snack on youngsters or even smaller adults. The babies can mature quite rapidly too, reaching breeding size within just a little more than a year if they can find enough food.
As a pet, garter snakes as a whole are often overlooked in the captive trade, though for several understandable reasons. In most species, babies are often too small to eat even a whole small pinky mouse (requiring them to be chopped if this food is offered), and often prefer live prey items in the form of small fish, worms, or even tadpoles, and some species are especially particular about which kinds of fish, amphibians, etc. they'll accept. They're fairly skittish animals, some highly curious and docile but others wanting nothing more than to run and hide or even bite in defense so not every individual is a good handling animal. And as they start eating almost immediately after birth (and shedding, unlike most familiar snakes that take a week or two to shed and then begin to feed after hatching) food has to be ready on hand or purchased very soon after to avoid the risk of any neonates starving. And, a lot of people like snakes that get to a decent size to work with, and many garters even as adults just don't get very big.
The Chapala garter, and other Mexican subspecies for that matter, would seem to be the exception; babies are often big enough to take whole pink mice and will often take frozen-thawed right away or be able to be convinced through mild scenting, many of the adults quickly become fairly docile with regular handling and so are great both for display and interaction, and they get big enough that it's harder to accidentally drop one that's sliding off your arm. However, with the restricted ranges of many of the subspecies and the limitations their native country has on exports, many of these are classed as vulnerable if not endangered and are restricted mostly to the bloodlines already outside Mexico for breeding purposes. The healthiest babies come from crossing bloodlines too, and with few people really working on them that can make it difficult to acquire unrelated stock, thus keeping these relatively rare and now rather sought after in the herpetoculture trade.
Hope is not lost in getting this species more established and appreciated however; my pair is from two entirely separate sources and so very likely to be unrelated, giving the best chance I can get of producing healthy offspring in the future (given that they are, in fact, a pair; Maya is a year or so older than Cymus and was closer to his size and shape last year, so there's a slight chance that the sex I was told when I received her could be mistaken, but considering all points this seems unlikely. Even back then her head and neck were thicker than his are now, and the difference in the appearances of their tails could grow more distinct as he ages). I am not the only one with intent to breed these species either, and interest in garter snakes is increasing as people learn how to take care of them better so more people will be apt to take on the challenge.
So, should you want to get a Chapala garter, what should you know? Overall, about the same basic care requirements as any other garter, but perhaps on a slightly bigger scale: this is a snake that does well with room to move, and often even things to climb and bask on, so don't be too skimpy on the overall size or furnishing of the enclosure for a potentially 4 foot plus active snake. Heating can be provided either with an under-tank mat or a lamp system; while they don't need UVB lighting to do well it's not uncommon for them to just enjoy sitting under a good light. In my case, they've got a ceramic lamp nearby and also get the sun every day for a period through an eastern window, providing heat as well as a natural daytime cycle. Garters tolerate cooler conditions overall than many other snakes, so an overall temperature in the low to mid 70's Fahrenheit is often adequate, SO LONG AS there is also a basking point that gets a fair bit warmer (into the upper 80's or so) so they can properly thermoregulate. The tank should also possess several hiding locations, and a water bowl big enough for the snakes to fully submerge and move around in (swimming is important for a happy garter).
Feeding is often relatively straightforward, as these snakes often readily take frozen-thawed rodents which are nutritionally complete, and on a diet of mice or rats the proper size feeding once a week or so is plenty (correct size is approximately the thickness of the snake's midbody, or slightly larger). If you like giving variety though, or have a stubborn one who doesn't like mice, then often they will take various types of fish as well, such as slices of tilapia or even trout or salmon filet, or whole silversides and other small baitfish like guppies. Avoid, however, any fish that are high in thiaminase such as rosy-red minnows, goldfish, and some of the other common feeder fish, as this can cause sever vitamin-B deficiencies and kill the snake (some have reported success with soaking said fish in a vitamin-B solution beforehand, thus counteracting the vitamin loss, but this may be touchy especially for a newer caretaker). Feeding fish, frogs (preferably pre-frozen to avoid parasite risks), or earthworms (not red worms!) requires more frequent feeding however to maintain proper nutrition, and often either a variety in offerings or nutrient supplementation to be added to their food, so if these are chosen be ready with more than one offering and with the supplements needed to keep them healthy.
There is one particular trait of garters though that make them extremely appealing as pets, and rather unique among snakes: they are a somewhat social creature, and actually seem to do better in pairs or small groups than they do alone, so it's almost an excuse to get more. Though one can often still easily keep a single garter particularly if it is well-socialized with regular handling, having a cage-mate may keep them calmer, more readily feeding, and may reduce stress overall so they live longer lives (and a healthy garter, especially the large ones like the Chapalas, may live 10-15 years or more). This has been evidenced in my experience too, by the addition of Cymus to the environment; almost immediately after his arrival the previously solitary Maya became a much more voracious feeder (before she often didn't like me hanging around while she ate, and now she will happily grab her food and attempt to wander off with it while I'm still there, no cares given if even picked up while eating to put her back) and is less likely to immediately bolt when the cage is opened even if she'd always been calm once out (though she'll be more apt to try and explore now, which makes cleaning the cage difficult as I must wrangle her back every few seconds). Just make sure if you house more than one together, that they have either plenty of food readily available to grab, or they are separated to feed or at least teased to separate ends of the enclosure; if they accidentally grab the same food item, there is the risk one may inadvertently eat the other. Additionally, keeping males at least physically (though perhaps not visually) separated from females will also be needed to avoid unplanned mating if one does not desire that experience; the same sex, of course, can be housed together with no such risk.
Overall, garters are a fascinating animal to keep, especially when they are a species with rich background like the Lake Chapala. Restricted in the wild, much care should be taken to appreciate and support any conservation projects aimed to protect it and its habitat, and captive breeders should seek outcrossing to maintain the healthiest animals in the trade. This is a species that is extremely well-suited to captivity, large enough to handle easily and typically tame, as well as typically a ready feeder on a variety of foods. Do your research of course before acquiring one (as it should be with any pet), but they will undoubtedly be a great pet for anyone who gets one, active and intelligent, and ever so personable.