| 1 | Cottonmouth |
Maximum length: 189.2cm.
Probably the most feared of all US snakes. Cottonmouths are widespread in the southeastern USA, occurring from central Texas to southeast Virginia, and all the states between. They belong to the same Agkistrodon group as copperheads, but are much more aquatic in nature, and boggy swamps are one of their favourite places to lurk.
Cottonmouths range from 90-150cm, and are recognisable by a dark brown/black body contrasting against a snowy white mouth lining. They have a strong dietary preference for frogs, such as southern leopard frogs, and move at sluggish speeds while slithering along swamp shores. Cottonmouths sometimes shock people by poking their heads up from swamps like a submarine periscope. Dog walkers often bump into them while walking along trails directly adjacent to swamps.
Despite the fear surrounding cottonmouths, life is harder for them than they’d like to admit. They have endless enemies in their swampy habitats, and not many allies.
Hungry alligators love to eat them, snapping their jaws shut and disappearing into the depths. The snapping turtle finds cottonmouths simply delicious, and they even have a fish predator in the largemouth bass. Overhead, meanwhile, there’s the beating wings of blue herons and whooping cranes.
| 2 | Red-bellied black snake |
Maximum length: 254cm.
The main Australian swamp snake you should keep an eye out for. Red-bellied black snakes are a dangerously venomous species which are found all over the eastern half of Australia, including near Sydney. They’re a semi-aquatic snake, also frequenting meadows and grassland, but being particularly common in waterbodies, such as boggy swamps filled with years of decaying mulch.
Red-bellied black snakes have a mainly amphibian-based diet, including prey like the emerald spotted tree frog. They’re a diurnal species, moving by day, and are excellent swimmers. They use these skills to prowl the swamp surface for frogs, looking for strange, subtle movements which their reptile brains instinctively recognise as hopping.
Red-bellied black snakes can move slowly when necessary, allowing them to blend in with rotting vegetation floating on the swamp surface. When a frog draws near, they suddenly move with a burst of speed. They allow their neurotoxic venom to sink in, then retreat to the swamp’s edge to swallow their meal in peace.
| 3 | Western ribbon snake |
Maximum length: 126.8cm.
A species of many wet environments: streams, rivers, lakes, and forest swamps filled with decades of slime. Western ribbon snakes (Thamnophis proximus) are an extremely widespread species, ranging from Chicago through Texas and Mexico all the way to Costa Rica.
This is one of the most likely swamp snakes for a US citizen to encounter. They’re not found in remote areas, and can easily appear in a swampy forest directly adjacent to your back garden. But even the densest swamps surrounded by muck and twisting vegetation are acceptable living quarters for them.
Western ribbon snakes live in a competitive environment, hunting frogs and red-backed salamanders, while weaving past the hungry attentions of hawks, turtles and milk snakes. As a fellow swamp dweller, the cottonmouth is a confirmed predator, and may be their greatest nemesis of all.
This species has a mildly venomous saliva, which is barely capable of swelling a human’s hand. Western ribbon snakes are much thinner than their garter snake cousins, and their pale stripes are a light cream rather than yellow.
| 4 | Common keelback |
Maximum length: 100cm.
A harmless snake of northeast Australia, which sticks to stationary water bodies such as ponds and swamps. Though barely heard of globally, the common keelback is a regular neighbour of Queenslanders, who probably got bored of seeing them years ago. In winter, they prefer wide floodplains, while summer is swamp season.
Common keelbacks (Tropidonophis mairii) are quite timid around humans, and will sometimes flee at high speeds if startled, swimming to the opposite side of their swamp like a speedboat. Others such as pregnant females will find thick stands of watery vegetation to hide in, or dive below into the swampy depths.
Common keelbacks prey overwhelmingly on frogs, with a small smattering of toads, which isn’t surprising given their swamp-loving ways. Species include ornate burrowing frogs and even the poisonous Dahl’s water frog.
Common keelbacks are usually safe in their swamp strongholds, but they still fall victim to cunning predators, including hawks and owls. Their eggs are also consumed by fellow snakes, namely the slatey grey snake.
| 5 | Blood python |
Maximum length: 2.6 metres.
A brutishly thick python, which typically measures 90-180cm. Blood pythons (Python brongersmai) dwell in southern Thailand, peninsular Malaysia and eastern Sumatra, and love swampy areas of forests most of all. This is one of the thickest-bodied pythons of all, with explosive brute force as it lunges against your legs.
Though non-venomous, blood pythons have brutally sharp fangs, which they sink into people’s legs without remorse, with a thuggish gleam in their eyes. Those in Malaysia are more aggressive, while the Sumatran versions are calmer. The signature bloody patterns give them great disguise in their swampy realms, with some patches resembling fallen jungle leaves and the darker patches resembling swampside mulch.
This is a pure ambush snake, which rests motionless for days or even weeks by the swamp’s edge. Rodents are overwhelmingly their main prey. Blood pythons are also drawn to palm oil plantations and their shady canopies, particularly if these are adjacent to swampy forests. This species probably encounters humans more today than they did in pre-industrial times, as no sane person would head to their forested swamp lairs willingly.
| 6 | Plain-bellied water snake |
Maximum length: 163.6cm.
This 75-120cm snake can be found all over the southeastern US, except for Florida, where they only inhabit parts of the panhandle. Plainbelly watersnakes (Nerodia erythrogaster) are found in Texas, Georgia, Alabama and the Carolinas alike. As the name suggests, they’re recognisable by a bright belly with no patterns, which differentiates them from the northern watersnake nearby.
Plainbelly watersnakes mainly prey on frogs and toads, such as American bullfrogs, squirrel treefrogs, and southern toads. Compared to their Nerodia watersnake cousins, plainbelly watersnakes are the most likely to be found in swamps. Northern watersnakes (Nerodia sipedon) are less adventurous, sticking to their rivers and crystal clear lakes.
However, studies show that plainbelly water snakes stray significantly further from their home water bodies, often moving 100s of metres to upland areas in forests. This makes them much more likely to settle down in a boggy swamp for a few days, before moving on again.
It’s even possible that you could find a plainbelly watersnake living in your local swamp one day, only for it to have mysteriously disappeared the next day. A teenager could bring along his mates to his local forest swamp, insisting that he’d seen snakes in there yesterday, only to be laughed at as nothing happens.
| 7 | Dice snake |
Maximum length: 200cm.
A mildly venomous, semi-aquatic snake, which appears in the lakes, rivers and swamps of central Europe eastwards. Countries where you’ll find the dice snake (Natrix tessellata) include Germany, Slovakia, northern Italy, Bulgaria, Turkey and even Israel.
The dice snake reaches a maximum of 130cm, except a handful of fluke spots where they grow to 2 metres. Their appearance is finely tuned for blending into aquatic environments, disappearing into lakes and green, slimy swamps equally well.
This is an abundant snake, with hundreds in certain locations, yet it’s still perfectly possible to walk right past a dice snake hotspot and not realise. You could see a strange pair of eyes in a swamp, look back and then see nothing, causing you to question your own sanity.
Dice snakes mainly feed on fish, with a side helping of frogs. They’re capable of inflicting swelling in humans, and have a deceptive trick where they spew blood from their own mouths to feign death. Dice snakes are non-aggressive, and won’t slither directly up to you and attack. This swampy snake will only inject venom into you if you foolishly pick it up.
| 8 | Yellow-bellied liophis |
Maximum length: 112.1cm.
A friendlier-looking swamp snake, with large black eyes and a reasonable facial expression, rather than a cruel crocodilian snarl. The yellow-bellied liophis (Erythrolamprus poecilogyrus) is found in southern Brazil, Argentina and Paraguay, where they’re an extremely abundant and common snake. They mostly stick to wet areas, and swamps within forests are an especially common place to find them lurking.
With bright yellow scales contrasting against black, this species is much easier to spot amid green slime compared to other swamp snakes. Their swampy ways have led to a swampy diet, as 98% of their meals consists of frogs and toads. They have numerous defensive skills, including spreading a small hood similarly to a cobra.
The yellow-bellied liophis is mildly venomous, but has never caused a death in humans. Another of their colloquial names is the yellow-bellied swamp snake. Creatures they overlap with in Paraguay and Argentina include the yellow anaconda, Brazilian smooth snake, and leopard keelback. Whether these snakes are working together to entice humans deeper into swamps remains to be seen.
| 9 | Mud snake |
Maximum length: 207.0cm.
A semi-aquatic species of the southeastern US, which you’re most likely to find in dark Floridian swamps. Mud snakes can exceed 2 metres, and might be the most harmless large snake in the USA. They’re completely non-venomous, and even attempting to bite is exceptionally rare. It’s possible to wade into a swamp, pick one up with your hands and suffer no ill effects at all, except maybe 20 alligators suddenly arriving at once.
The swampy expanses of the everglades are a paradise for this snake, as are twisting cypress corridors. Mud snakes aren’t hard to find if you live rurally, though they do like the darkest, eeriest swamps. They mostly prey on amphibians, such as the three-toed amphiuma and mole salamander. They’re sometimes swallowed themselves by cottonmouths, their fellow swamp lover.
Harmless they may be, but mud snakes can look very eerie at times. At dusk, when the fading light reduces the visibility of this already dark snake, casting shadows over their swamps, the effect can be like a 1950s horror film. They also have a disturbing tendency to float motionless on the water surface, coiled in a complete circle.
| 10 | Orange-bellied swamp snake |
Maximum length: 88cm.
A dedicated swamp snake of central American rainforests, including Costa Rica, Honduras and Nicaragua. Orange-bellied swamp snakes (Tretanorhinus nigroluteus) are non-venomous and have no human deaths to their name, or even serious injuries. Their swampy adaptions include upturned nostrils, which allow them to submerge and poke only the tops of their heads up while still breathing.
Rather than swamps near your backgarden, orange-bellied swamp snakes dwell in boggy swamps in the most inhospitable, humid jungles. Even reaching this snake is a nightmare. Firstly, you have to slash your way through dense foliage.
Then there’s thick bogs which you could sink in up to your boots. The branches overhead are home to shrieking monkeys, issuing warning cries to their fellow kind. Once you reach the swamp, the journey might end up being in vain. Orange-bellied swamp snakes are shy, and won’t simply appear at your request.
Orange-bellied swamp snakes average at 50-60cm, with a record of 88cm. The swamp is central to their very survival, as when threatened, their default is to dive deep below the surface. Generally, they spend their days in the swamps themselves, and the nights prowling their shores, searching for fish and frogs, their main prey.