Think of Oklahoma and you probably think of the Great Plains, world-famous musicals, or the cultures of the old Muscogee and Cherokee tribes. That’s what’s famous about this great cut-out of central USA. Less famous are the dangerous animals in Oklahoma…
Well, that’s what we’re here to talk about: The critters and creatures you probably don’t want to see while you travel the undulating prairies and the wooded Ouachita Mountains of this gorgeous state.
We’ll run through just seven of the most dangerous animals in Oklahoma. There’s a special focus – as you might expect – on the venomous snakes of the territory (rattlers, especially), along with a look at some of the more elusive and bigger beasts that could cause potential issues. Let’s get started…
Black widow

Ah, the black widow. Just the name is often enough to strike fear into the hearts of arachnophobes the planet over. These are unquestionably the deadliest of spiders in the Sooner State. In fact, they’re the deadliest of all the spiders in the USA and much of North America more generally, since they are the only eight-legged critters to possess a powerful neurotoxin venom that can kill, but more on that later.
Black widows are pretty commonplace throughout Oklahoma. They’re regularly spotted in built-up areas too, from the suburbs of Oklahoma City to the streets of buzzing Tulsa. That’s because they quite like to inhabit dry, shady areas – AKA garages, sheds, barns, and even cupboards and closets. The official advice is to take special care when rummaging around said areas, particularly during the main breeding season between May and October.
What about the bite? Well…it’s hardly pleasant. There’s a toxin here that can cause some serious issues. In fact, it’s even got its own name: Latrodectism. Victims often feel intense pain at the site of contact, followed by uncontrollable sweating and goosebumps, eventually leading to spasms and potential tissue breakdown. These symptoms can last up to four days in all!
Prairie rattlesnake

This iteration of the pit viper genus even has prairie in its name. So, it should hardly come as a surprise that they’re pretty big fans of the natural landscapes of OK state. After all, much of this vast territory is given over to the Great Plains, where endless horizons of dusty grasses and intermontane meadows stretch on for as far as the eye can see.
Mhmm, believe it or not, the prairie is precisely where the prairie rattlesnake likes to live. They can grow to around a meter in length and have a fantastic camo pattern of light beiges and greys, topped with intermittent dashes of darker browns. You try spotting one of them as you hike the flatlands around the Cimarron River basin. It’s nigh-on impossible!
But you will want to keep an eye out. That’s because these guys wield a horrible mixture of hemotoxin and neurotoxin venoms. It can do all sorts, from excessive swelling to tissue degradation around the site. They hardly hesitate to attack, either, because they are very territorial and don’t like being disturbed. Not a great combo, eh?
Mountain lion

The rare and elusive mountain lion was once completely extinct in the state of Oklahoma. However, things seem to have changed, as there have been a number of reported sightings of the great beasts since the turn of the millennium, most recently in 2020, when there were actually more sightings than in any other year since records began. So, they’re back. Nice. But what does that mean for the Okies themselves?
There’s no doubt that a mountain lion certainly deserves a place on this list of the most dangerous animals in Oklahoma. These guys are proper predators – occasionally even the apex predator of their habitats. Also known as cougars or pumas, they have a stealthy, swift attack and are masters of the neck bite, a way to kill prey that involves cutting off essential blood supplies to the brain and spinal cord.
All that aside, human-lion encounters in Oklahoma remain very rare indeed. These solitary creatures almost always prefer to avoid built-up areas and will often run in the face of loud noises. That said, if you do find a confrontation is inevitable, the most common advice is to make yourself as big as possible and to back away very slowly. Thankfully, there’s no recorded lion attack in the state Oklahoma to date.
Western diamondback

The western diamondback is one of the toughest serpents in the USA. It’s got a very worrying reputation as the most prolific biter in the whole of the country, and it’s even responsible for the most snakebite deaths in large parts of northern Mexico. They are known for their aggressive disposition, which they’ll make known with a trademark rattle of the tail bones.
Diamondbacks actually live all over the southern USA. They can be found from south California to the coastline of eastern Texas. In Oklahoma, they dominate the central part of the state. Their main habitats are mesquite grassland, scrubland, and piney woodlands – so, there’s plenty of spots they’re sure to like in the Sooner State!
Now, onto the bite. Yikes! This one’s not nice at all. After striking hard and fast, the western diamondback will leave you pumped full of a cocktail of proteolytic enzymes. Those are highly toxic chemicals that cause bruising, death of living tissue, and uncontrollable hemorrhaging. Studies have shown that a diamondback can inject up to 800mg of venom in a single bite. That’s more than enough to kill, and an estimated 15% of attacks end up being deadly to humans.
Pygmy rattlesnake

If you’re keen to explore the hillier parts of the Sooner State around the Choctaw Nation south of the Arkansas River (a truly beautiful part of the state, you know!) then the pygmy rattlesnake is certainly one worth knowing about. It’s small but deadly, and unquestionably one of the most dangerous animals in Oklahoma.
Growing to a max of about 60cm at full adulthood, these guys are among the more bijou snakes in the state. But don’t let that distract you. They possess a hemorrhagic toxin that can wreak havoc on your blood and cardiovascular systems. They’re not often deadly but might just put you in hospital for weeks and weeks on end!
Pygmy rattlesnakes usually live in mixed woodland areas and plains and like to be close to rivers. They actually quite often come into contact with humans because of their habit of sunning themselves on the road. The bad news is that you might not even get the usual forewarning offered by rattlers, since this one’s tail is so small that it only makes a light buzzing noise.
Western cottonmouth

With the striking Latin moniker of Agkistrodon piscivorus leucostoma, this slithering specimen really does sound like something out of a Homeric epic. Truth be told, recent DNA analysis of the species has determined that it’s not actually a subset of the more generic cottonmouth as was previously thought. Either way, it’s not something you’d want to encounter on your travels through the USA.
The reason? It’s a feisty customer. A study showed that this snake preferred confrontation over flight in a whopping 78% of cases, making it a truly aggressive viper to come into contact with. It’s also one of the world’s only semiaquatic vipers, which means it’s just as efficient in the water as it is on the land.
The good news? The western cottonmouth, or just the cottonmouth, doesn’t cover the whole of the state of OK. The only places you’re likely to find it are in the extreme south and east of the territory. It’s much more common around the Mississippi River Valley and in Texas, where it often bites. The venom from these guys is pretty destructive, too, often leading to amputations and local necrosis.
Copperhead

Finally: The copperhead. This is one of the southern USA’s most ubiquitous serpents. Regular encounters with humans in Oklahoma, Texas, Mississippi, and the Carolinas, along with Chihuahua and Coahuila in Mexico, are thought to be directly related to the fact that it’s evolved to freeze rather than to run away, meaning it’s often stepped on and caught up in skirmishes with humans.
Copperheads are another viper. They have the trademark diamond-shaped head that protrudes over the opening of the mouth, marked out by its distinct ochre coloring and double dots by the back of the eyes. These snakes rarely grow to over a meter in length, although the largest ever recorded was a whopping 139cm from end to end!
Though dangerous, bites from a copperhead rarely prove fatal. Experts believe that they don’t usually inject enough venom to cause death in humans. On top of that, they often produce so-called “dry bites” that don’t involve any envenomation at all. That said, those who do fall victim often get symptoms like excessive swelling and nausea.
The most dangerous animals in Oklahoma – a conclusion
This guide to the most dangerous animals in Oklahoma outlines just a few of the creatures that we think it’s worth being wary of when you come to travel the home of the Great Plains and the wooded Ouachita Mountains. They shouldn’t be too much of a problem if you’re sticking to the bar-filled streets of Oklahoma City, but they might be an issue if you’re looking to head into the outback and explore the prairie and the peaks.
What’s the most dangerous animal in Oklahoma?
The most dangerous animals in Oklahoma are snakes. There’s no doubt about that. There are a few species here that can be fatal to humans, like the diamondback, the cottonmouth, and the pygmy rattlesnake. They all possess a powerful venom that can kill if left untreated.
Are there dangerous spiders in Oklahoma?
There are dangerous spiders in Oklahoma, although not many. The most feared of the lot has to be the black widow. It’s a famous crawly that has a venomous bite that can lead to local swelling and intense pain, although it’s rarely fatal in humans.