| 1 | Blackbelly garter snake |
Maximum length: 86.4cm.
This garter snake is easily recognisable by its vivid black and yellow colours, or sometimes fully black. The blackbelly garter snake (Thamnophis melanogaster) lives on the high altitude Mexican plateau, mostly above 2000 metres, with an all-time altitude record of 2828 metres above sea level. It’s common near Mexico City, and is a water lover which spends its days in large lakes, small creeks and also manmade canals.
This species appears in several large lakes popular with tourists, including Lake Cajititlan, Lake Chapala, and Lake Cuitzeo. They often live in these scenic lakes alongside close relatives, such as the Mexican garter snake (Thamnophis eques). Their average length is 50-60cm, and males and females are exactly equal in size.
Blackbelly garter snakes are confirmed to prey on earthworms, leopard frogs and crayfish. Leeches are another staple, and they’re even skillful enough to distinguish between species.
In 1995, a study gave this snake scents and live animals of two leeches: the tiger leech, which is a scavenger, and the Mexican leech, a traditional blood sucker. The blackbelly garter snakes much preferred the former. Initially, they attacked both, but gradually gave up on the Mexican leech, while continuing to guzzle down tiger leeches ever more vociferously.
| 2 | Goldenhead garter snake |
Maximum length: 89.2cm.
The goldenhead garter snake (Thamnohis chrysocephalus) is one of the most recognisable members of all, despite being relatively uncommon. This species is found only in southern Mexico, particularly near the city of Oaxaca. They particularly love pine oak forests, where they take shelter under fallen tree limbs. In fact, it’s believed that the collection of large branches for firewood is putting them under pressure.
The first ID sign of this species is the signature golden head, which isn’t a gimmick it uses to impress its mates, but a feature it is born with, which accelerates into adulthood. The second is that this is a rare garter snake to lack a bright vertebral stripe. Whether blotchy, plain or striped, garter snakes worldwide are consisting in having this spinal stripe, but Thamnophis chrysocephalus is a rare exception.
Golden-headed garter snakes are multi-skilled, as they can swim, climb, and thread their way along narrow branches to equal effect. They’re less aquatic than some garter snakes, but are usually found near a water body.
This species averages at 50-60cm, and their Latin name of Thamnophis chrysocephalus makes perfect sense. “Chrysos” translates to golden in Greek, while “kephale” means head.
| 3 | Longtail alpine garter snake |
Maximum length: 60-70cm.
The longtail alpine garter snake (Thamnophis scalaris) resides in the volcanic belt of south central Mexico, from the regions of Jalisco to Veracruz. This is a species of high altitudes, ranging from 2103-4273 metres above sea level, avoiding towns and cities lower down. They’re found in similar regions to blackbelly garter snakes, but rarely coexist with them directly.
The reason is that longtail alpine garter snakes are less reliant on water than most members. They’re usually found in areas with permanent pools or streams, but tend to stick to the sweeping grasslands, hills or pine oak forests next door. Consequently, they eat far fewer fish and amphibians. A study found that 81% of their diet consisted of earthworms, while adults added eastern deermice and transvolcanic alligator lizards.
They were also recorded eating a venomous snake: the dusky rattlesnake (Crotalus triseriatus), a staple of Mexico’s highlands. Longtail alpine garter snakes have predators of their own as well, falling victim to a Mexican garter snake in one sighting. It’s a never-ending battle for snake dominance in Mexico’s volcanic highlands.
Longtail alpine garter snakes hibernate in tiny holes in the ground, in the middle of grassy hillsides. Scientists found one with a miniscule entrance, just 1-1.4cm. Six Thamnophis scalaris fled into this hole, while another two fled for open grassland, but were later seen wriggling their way in. Scientists later used a probe, and found this tiny hole to be longer than the length of the probe, which was one metre.
| 4 | Mexican wandering garter snake |
Maximum length: 75cm.
This Mexican species is still mysterious as of 2023. Nothing is known about its diet, nor of the predators that attempt to eat it.
Mexican wandering garter snakes (Thamnophis errans) are most commonly found in a single mountain range: the Sierra Madre Occidental. These peaks run continuously through northwest Mexico, and Thamnophis errans makes its home in their plentiful montane pine-oak forests. Mexican wandering garter snakes particularly like areas close to streams, where they hang out near logs and occasionally under rock piles. Western Chihuahua state is one of their particular hotspots.
Mexican wandering garter snakes are contained entirely within Mexico. They were originally considered to be a terrestrial garter snake subspecies, but their scale counts differed, and they even have a differently coloured tongue. The two species are separated in northern Mexico by 280 kilometres of uninhabitable desert.
It’s not surprising that they were confused, as this garter snake is very difficult to recognise, with the classic garter design of parallel yellow stripes, one down the spine and one on each flank. Their body colour is mainly a drab grey, with no unique colours. Mexican wandering garter snakes reach 75cm, and are commonly seen weaving through beds of twigs on the floors of forests.
| 5 | Yellow-throated garter snake |
Maximum length: 77.2cm.
This species has a large territory in southern Mexico, ranging from the highlands near Mexico City to the outskirts of Durango. Yellow-throated garter snakes (Thamnophis pulchrilatus) are timid in personality, and have no desire to duel humans for bragging rights. Their favourite habitats are moist grasslands surrounded by patches of pine-oak forests.
This species typically hides under stones, and will flee if the stone is flipped over. If their way is blocked, they’ll coil into a circle and hide their head, protecting their brain, before producing a foul snake smell and moving their tail in slow, steady movements. This repertoire is strangely similar to the grass snake of the UK.
Despite their yellow throat, another defensive skill is revealing bright blue skin between their scales, which is supposed to scare predators off. They achieve this by elongating their neck sideways, while facing the enemy head on.
Yellow-throated garter snakes like altitudes of 2000-2500 metres. Compared to US garter snakes, little research has been conducted on them. Yet they have a few confirmed prey, including amphibians such as Bell’s salamanders and mountain tree frogs (Hyla eximia). Thamnophis pulchrilatus has yellow parallel stripes contrasting against black, and a juicy red tongue with a black tip.
| 6 | Highland garter snake |
Maximum length: at least 65cm.
One of the most southerly garter snakes on Earth. Highland garter snakes (Thamnophis fulvus) live in extreme southern Mexico, Guatemala, and El Salvador, and reach an extreme southerly point of central Honduras. They live well away from densely populated cities, with their honking taxis and bright billboards. You’ll only find the highland garter snake in grassy plains and pine-oak forests above 1600 metres, with a maximum altitude confirmed so far of 3710 metres, making them one of the highest members.
Highland garter snakes live a shy, quiet life. They’re particularly attracted to juniper bushes, and can vanish into a pile of rocks in the blink of an eye. They also swim in manmade cattle ponds, as well as the usual rocky streams.
This snake is hard to recognise, but one sign is that their vertebral stripe is relatively dull, compared to the neon colours of other garter snakes. They also have a stripe on each flank, while the dark scales between have subtle patterns like a rug. Then there’s a proper special feature: this is a rare garter snake to have a fully black tongue.
Their Latin name is Thamnophis fulvus, and fulvus translates to “tawny, reddish yellow”. Highland garter snakes are one of nature’s mysteries, but we have a few morsels of knowledge from captivity. A breeder produced a litter of ten newborns, and reported that his adults fed enthusiastically on rodents. Most prey from the wild, meanwhile, have been amphibians. Highland garter snakes are confirmed to prey on Zacate Blanco tree frogs, montane sheep frogs, and the salamander Bolitoglossa rostrata.
| 7 | Mexican garter snake |
Maximum length: 130.7cm.
The Mexican garter snake (Thamnophis eques) is the most sprawling species in Mexico, covering a large territory and also spilling into Arizona. This snake is a particular water lover, spending its days swimming around lake shores, hoping to spot a hopping dot in the distance representing an amphibian.
Because of their aquatic ways, Mexican garter snakes have accumulated 10 different subspecies. Many of these subspecies live in just one lake basin, becoming stranded as water levels recede, freeing them to mutate in various directions. These vary wildly by appearance, making the Mexican garter snake very difficult to recognise. For example, the subspecies Thamnophis eques virgatenuis has vivid blue stripes instead of beige.
This is also one of the largest garter snakes. The record was once 121.6cm, before being smashed through with 130.7cm in 2012. The common garter snake maxes out at 137.2cm, while the giant garter snake (the world’s largest) has a record of 164.6cm.
Mexican garter snakes prey on amphibians, including the Liobates American waterfrog group. They also prey on fellow snakes, including a fellow member of this list: the longtail alpine garter snake.
| 8 | Rossman’s garter snake |
Maximum length: at least 75cm.
One of the rarest garter snakes in all of Mexico. This species is found mainly in the small westerly state of Nayarit, where it lives a quiet life in freshwater wetlands. They also appear in roadside ditches, springs, and seepage runs fed by regular thunderstorms.
Rossman’s garter snakes (Thamnophis rossmani) appear along one small river: the San Cayetano river, but not in the river itself. Instead, they like to lurk in riffles, fast flowing streams over a rocky base, where they ambush fish as they swim past.
There’s a happy story with this snake, as a 2000 study mentioned that: “Thamnophis rossmani may be in grave danger, if not already extinct“. But photographs have turned up since then, including the one above. Rossman’s garter snake is most closely related to the Mexican garter snake (Thamnophis eques), but the dark spots on its flanks are significantly smaller.
This garter snake is medium in length for the Thamnophis clan. Females average at 57.0cm, while males average at 57.9cm. The longest female discovered measured 74.5cm, but this was missing a fraction of its tail, and would have been even longer otherwise. This species has the classic garter snake tongue: bright red with a black tip.
| 9 | Short-tail alpine garter snake |
Maximum length: 56.7cm.
The sister species of their long-tailed cousin. The short-tail alpine garter snake (Thamnophis scaliger) not only has a significantly shorter tail, but is estimated to be the third shortest garter snake worldwide. The record length was just 56.7cm (versus 137.2cm for a common garter snake), and this keeper found that most are shorter, having bred them for years. His adult females ranged from 44.8-51.2cm, while his adult males ranged from 41.2-47.3cm.
Like the longtail alpine garter snake, this species preys mostly on earthworms. It’s a citizen of the Mexican plateau, and has been found at elevations from 2160-2740 metres.
Short-tail alpine garter snakes are often found in peaceful grassy valleys with cows and horses grazing, and a river flowing through the centre. They appear on the borders of forests near small streams, and love to rest under small rocks for shelter. They can appear in drier, arid grassland as well. This garter snake is particularly abundant in the countryside outskirts of Mexico City, which lies at an altitude of 2575 metres (the 9th highest capital city).
Compared to the Mexican garter snake, this species is easily recognisable. Its flanks contain a series of dark blotches rather than the parallel vertical stripes of most species, including US staples like the common garter snake. However, their spine still has a vivid stripe, and this varies from white to neon orange.
| 10 | Bogert’s garter snake |
Maximum length: 39.6cm (but poorly researched).
This garter snake lives exclusively in the Oaxaca region of southern Mexico. It only became an official species in 2005, when Godman’s garter snake was reanalysed, and declared to truly be 4 separate species.
Bogert’s garter snake (Thamnophis bogerti) is recognisable by subtle physical features such as a head with no patterns, a tail comprising 25% of body length in males (23% in females), and 145 ventral (belly) scales in males, with 140 in females. There’s also two rows of round dots on each flank, between the spinal stripe and the lower stripe.
Bogert’s garter snakes live in oak woodland and pine-oak forests, and nothing is known of their diet or defensive techniques. However, they’re perfectly harmless to pick up, and will normally curl harmlessly around a finger.
This garter snake has a wide colour variety in the wild. In some snakes, the spinal stripe is bright, while in others the stripe is dim. The same is true for the dots, which sometimes blend into a darker background.