There are thought to be only 10 indigenous species of snakes in Puerto Rico. That’s great news for any ophidiophobes thinking of hopping over to the unincorporated US territory to enjoy the surf breaks and the sunny beaches, the cobbled lanes of Old San Juan and the rainforest-clad mountains this year. But it also gets better…
Of the 10 serpents that make their home on the island, only a single, solitary one has been noted as carrying a venom that can harm a human, and even that’s up for debate. That leaves 90% of the legless critters here in the “harmless” category, which is presumably why snakebite incidents – particularly ones that can ruin a trip – are generally very rare.
This guide to the snakes in Puerto Rico will focus in on five of the most intriguing types that you may just encounter. We’ll offer info on what they look like, where they live, and – most importantly of all – whether they’re the sole culprit that has the only venomous bite in this tropical escape and spring break hub in the heart of the Caribbean. Let’s begin…
Puerto Rican boa (Chilabothrus inornatus)
The Puerto Rican boa is probably the most famous of all the snakes in Puerto Rico. That’s mainly down to the fact that it can grow pretty massive. Yep, these guys can clock up total lengths of nearly two meters at full adulthood. That’s longer than your average human height and just about the same length as a fully grown female tiger, just for a bit of perspective.
Whopping great big length aside, the Chilabothrus inornatus can be spotted thanks to their distinct earthy color scheme. Thin bodies are usually characterized by alternating spots of dark brown and musty grey, which gets noticeably paler on the underside of the animal. They also have a small head with dark brown scales on the bottom of the chin and dark, pearl-like eyes set on the flanks of the cheeks.
Boas aren’t venomous but they aren’t powerless, either. These guys are part of a genus of creatures known as constrictors, which catch and kill prey by clamping them in their jaws like a vice in order to use long and muscular bodies to entwine around the body, leading to eventual suffocation. This phenomenon lets them feed on creatures that are generally much larger than what other snakes can hope for – think geckos and even adult birds.
The Puerto Rican boa is mainly found in the karst region of northern Puerto Rico. That’s a landscape that really lends itself to these semi-arboreal animals since it’s filled with dank caves that has an abundance of bats (a favorite meal for the boa). Scientists have even observed these guys hanging by their tails at the entrance of caves in the karst region, waiting for unsuspecting bats to whizz on by.
Puerto Rican racer (Alsophis portoricensis)
Here it is: The Puerto Rican racer, the ONLY venomous snake that’s known to exist on the whole island territory. This critter resides all over, from the lowland coastal plains near the beaches to the protected mid-altitude forests that cover the El Yunque National Forest deep in the hinterland. In fact, it’s quite regularly spotted by travelers on the trails there, particularly on the popular Big Tree Nature Trail that pierces right through the heart of the reserve.
You’re looking for a snake that measures around about three or four feet at its total growth. It’s thin and slender, with a distinct scale organization that runs elegantly from snout to tail. When it comes to the coloring, the Puerto Rican racer seems to have evolved to fit in seamlessly with the undergrowth of the woodlands of the isle. It has a light brown on top and a darker brown bottom side, helping it mingle perfectly with the decaying leaves and wood chip.
As we’ve mentioned, the bite of the Alsophis portoricensis is the only snakebite you really need to be wary of in Puerto Rico. Traditionally thought to be harmless, scientists now believe that the creature possesses a toxic salvia and venom that can lead to local health complications, heavy bruising, and swelling that can extend beyond the site of contact. However, there have been zero recorded incidents that have been fatal in humans, and the local hospitals are now equipped with the skills to minimize and counteract bites from the racer.
The bad news is that these snakes are very aggressive and territorial. If you do spot one, it’s best to keep your distance as they can quickly change moods. When in attack mode, they will fan the hood of their neck in the same style as a king cobra. That’s usually enough to fend off would-be attackers but the pose is quickly followed by a bite strike that sees the snake latch onto its prey. Left alone, the racer usually dines on small rodents and lizards.
Common worm snake (Typhlopidae)
Okay, so it’s hardly the most flattering name for a snake, but the common worm snake really does look just as its moniker suggests. It’s pale pink with a paler underbelly, is virtually smooth the whole way from its head to its tail, and it has an almost imperceptible head at the tip of the body. Basically: It looks just like a worm!
The type of Typhlopidae that can be found in Puerto Rico is actually common across the whole of the Caribbean region. It’s known by the more specific Latin name of Antillotyphlops platycephalus and, oddly, is completely blind. This type also has a characteristically flat head and comes to tip at one end where there’s a light brown concentric ring around the whole torso.
These guys like to burrow – are we sure they aren’t just worms? – so live predominantly at ground level in muddy and remote parts of the island. They are mainly found in woodland parts of Puerto Rico, from the more undeveloped karst regions of the north away from the buzz of San Juan to the protected landscapes of the El Yunque National Forest.
Mona Island boa (Chilabothrus monensis)
The Mona Island boa gets its name from the fact that it originates on the tiny pinprick of an island that is Mona. Check the map, folks – it’s little more than a speck that dots the glistening Caribbean Sea between PR and the Dominican Republic. Uninhabited and tiny it might be, but it’s still an official part of the US territory and hosts this eponymous serpent. So, here it is on our list…
Just like the Puerto Rican boa before it, this one catches and kills its prey by squeezing them to death. Don’t worry, they aren’t anywhere near strong enough to do that to humans. They grow to about just half what their Puerto Rican cousins manage, clocking up around 100cm from snout to tail when fully grown.
On top of that, the Mona Island boa is generally considered extremely elusive and is actually rated as Near Threatened by the IUCN because of plummeting numbers in the wild. They tend to stick to heavily wooded areas, prefer to reside high in tree branches or even deep in the undergrowth between thickets, and only really come out at night.
Virgin Islands tree boa (Epicrates monensis granti)
The Virgin Islands tree boa is named as such because it’s more commonly found on the neighboring archipelagos of the United States Virgin Islands and the British Virgin Islands. Specifically, it has large populations on the pristine forested isle of Virgin Gorda in the BVI but only on St. Thomas in the USVI. However, it also shares forest space on Puerto Rico with the other constrictors of the isle.
Semi-arboreal, they tend to reside in the trees or on branches. However, they can also be observed on the forest floor tracking prey, though that’s almost always done in the dead of the night, so it’s very rare that you’ll witness the thrill of the chase.
Sadly, the Virgin Islands tree boa has suffered considerably due to habitat destruction and habitat loss in the last couple of decades. It’s thought that its numbers are now in freefall, and only a few pockets of healthy, sustainable populations remain in the region.
They look just as you’d expect a boa to look. A big, beefy body that can hit just over one meter in length culminates with a diamond-shaped head. The coloring is alternating brown and grey all the way to the bottom of the tail. To the untrained eye, these guys can easily seem just like the other two constricting species on this list of the most amazing snakes in Puerto Rico.
The most amazing snakes in Puerto Rico to know about – our conclusion
There’s good news for travelers fearful of meeting sliding critters over in this territory of the USA: There are only 10 species of snakes in Puerto Rico and only one of those is venomous. On top of that, a whole load of them are very rare boa snakes that target small rodents and reptiles, only come out at night, and live deep in the forest. The best place to spot snakes on the island is either in the reserves of the northern karst area or in the El Yunque forest.