What is the most dangerous mammal in the United States?

What is North America's most dangerous (non-human) mammal? Grizzly bears? Certainly Lewis and Clark on their way to the Pacific Ocean in 1804 thought so. In the early 1800s, some 50,000 grizzlies roamed the western United States, but their population has now dropped to around 1,000 in the lower 48 states. Bears, grizzly and black, killed 128 people in North America in the 20th century. What about mountain lions? Reports that mountain lions lurk in the hills and pick off women trail bikers certainly chill the blood. There have been 14 deaths in North America as a result of mountain lion attacks in the 20th century.

No, there is another creature roaming America's woods that is far more dangerous than these big predators. The most dangerous mammal in North America is…Bambi. The U.S. Department of Transportation estimates that white-tailed deer kill around 130 Americans each year simply by causing car accidents. In 1994, these predator deer had a banner year, causing 211 human deaths in car wrecks.

There are about 1.5 million deer/vehicle collisions annually, resulting in 29,000 human injuries and more than $1 billion in insurance claims in addition to the death toll. Deer also carry the ticks that transmit Lyme disease to about 13,000 people each year. Economic damage to agriculture, timber, and landscaping by deer totals more than $1.2 billion a year.

The problem, as nearly any suburbanite in the eastern United States knows, is that deer populations are exploding. Researchers estimate that prior to the arrival of European settlers, white-tailed deer numbered between 23 and 34 million. By the early 1900s, deer populations had fallen to between 300,000 and 500,000 animals. This population crash was a result of market hunting, that is, killing and selling the animals to butchers.

In 1900, the passage of the federal Lacey Act, prohibiting interstate traffic in wild game taken in violation of state law, effectively ended market hunting. At the same time, states like Pennsylvania and Virginia established game commissions that restocked deer and prohibited the hunting of does. Before the arrival of settlers, predators like wolves and bears, along with Native American hunters, had kept deer populations in check.

After their nadir in 1900, deer populations began to recover, rising to around 27 million animals today. State game commissions' constituents are chiefly hunters. Since hunters want more deer, these agencies have traditionally managed deer in order to maximize their numbers. This means that until recently, hunters could kill bucks but not does. In some areas, does outnumber bucks 30-to-1.

Deer overpopulation harms natural ecosystems. In high deer density areas, deer browsing prevents the regeneration of forests as deer eat nearly all the tree seedlings, destroy forest understory plants, and reduce overall species richness. Several studies found that deer browsing significantly reduces songbird numbers by destroying their habitats.

So how to protect ourselves from this dangerous mammal? Some more squeamish suburbanites, who generally hunt for their steaks and venison at the local supermarket, suggest using contraception. And in urban settings, contraception does work. "Shooting deer in urban parks and yards is illegal, unwise, unsafe, and publicly unacceptable," says Jay Kirkpatrick, director of ZooMontana's Science and Conservation Biology Program. Kirkpatrick has developed a vaccine using porcine zona pellucida proteins (pig proteins that surround pig eggs) that prompts a deer's immune system to produce antibodies that block egg fertilization. To be effective the vaccine must be injected, usually via dart guns, into deer four to five times over several years.

The vaccine has successfully reduced the number of deer on Fire Island in New York by 50 percent over seven years, and by 40 percent at the National Institute of Standards and Technology campus in Gaithersburg, Maryland, over the past five years. Kirkpatrick notes with dismay that state game commission bureaucrats refuse to use contraception on state-controlled urban lands because their hunter constituents fear that animal rights activists will try to require its use on free-ranging forest deer populations. Kirkpatrick notes that his center makes only 4,000 to 5,000 doses of the vaccine annually and that contraceptive vaccination is totally inappropriate for controlling deer populations on wildlands.

Hunters traditionally want to kill bucks with big sets of antlers. In the past century, state game managers have persuaded hunters to leave does alone to reproduce. However, an innovative program called Quality Hunting Ecology advocated by Brent Haglund, president of the Sand County Foundation in Wisconsin, is being adopted by some states. The idea is that hunters must kill two does before they can shoot a buck. This program reduces the number of fertile females. One apparent side effect of having fewer female deer is that testosterone levels rise in bucks that must compete for access to the remaining females, thus making them bigger trophy animals. Preliminary results of the Quality Hunting Ecology program in Wisconsin show that it does reduce the deer population and improve forest quality. Pennsylvania has just adopted a similar program for this current hunting season.

However, Donald Leal, a senior associate at the Political Economy Research Center in Bozeman, Montana (an environmental think tank), advocates an even more radical solution to the problem of deer overpopulation: a return to market hunting. Leal points out that the chief reason there is a deer problem is that hunters want to maximize their benefits, in this case, the number of deer available for them to shoot. So game commissions have adopted regulations that do that.

Leal is not advocating a return to the open commons that prevailed in the 19th century, which led to the steep decline in deer populations. But Leal does think that a system modeled on individual tradable quotas (used to manage some fisheries) would help keep deer populations healthy and in check. Right now, it is illegal for hunters to sell their excess game to anyone. This prohibition leads to absurdities like the fact that nearly all the venison served in America's finest restaurants is imported from places like New Zealand (where deer are an exotic species). Leal suggests that state game commissions could determine acceptable herd sizes and then sell quotas to hunt to individual hunters, outfitters, and restaurant cooperatives for the excess. Leal points out that his home state, Montana, already sells licenses to hunt bull elk to non-residents for around $1,000.

The political obstacle to re-establishing market hunting by creating a game quota system is that hunters would fiercely oppose it. They don't really want reduced deer herds. But perhaps city dwellers and suburbanites, tired of ramming deer with their SUVs and watching their landscaping be turned into deer pellets, will one day be able to outvote the hunter lobby and restore market incentives to managing wildlife. Then Bambi will no longer kill so many people and cause so much damage to our forests.

Let’s start by making one thing perfectly clear. This is an article about the deadliest animals in North America, and we’re using the dictionary definition of the word deadly. Which means all these animals “cause or tend to cause death” and most of them are “aiming to kill or destroy”.

Whilst our article does include some of the most dangerous animals in North America, we’re focussing exclusively on the killers. So although a bite from the fearsome-looking velveteen tarantula might be excruciatingly painful for a week, it doesn’t make the list.

We should also add that we’ve deliberately omitted two animals: mankind and mosquitoes. Whilst it’s arguable that mankind is responsible for more human deaths than any other animal, this is more of a moral question than a statistic. And we’ve missed out mosquitoes as they are not actually responsible for the deaths they cause — they are simply a carrier, or vector, for the parasites, viruses and bacteria that actually transmit diseases.

So here’s our pick for the nine most deadly animals in North America, which we’ve listed in reverse order. The number one killer in the US might surprise you, but don’t scroll down to the end right away or you’ll ruin the surprise!

We’ve also included a fatality total, using the latest available figures. That might sound a bit grim, but it’s the best way of learning just how deadly some of these animals really are. Here’s the list.

American Alligator and American Crocodile

North American Fatalities: Alligators: 0-1 deaths per year, Crocodiles: none

We’ve paired these two up, because most people can’t really tell the difference between alligators and crocodiles (here’s our hint: square snout = alligator, pointy snout = croc). In fact, both of them are from the same zoological family, called Crocodylia, which includes all crocodiles, alligators, caimans, and gharials. Only two crocodilians reside in the US. Fittingly enough, they’re called the American alligator (Alligator mississippiensis), and the American crocodile (Crocodylus acutus).

American alligators inhabit freshwater wetlands, such as marshes and cypress swamps. They’re prominent in the brackish waters of Florida and the Everglades, but you’ll also find them as far north as Carolina and as west as Texas.

Crocodiles prefer saltwater environments, and the American croc is a great ocean swimmer. So, outside of the USA, you’ll find them as far south as Peru and Venezuela, with particularly large colonies in Costa Rica and in the Dominican Republic. In the United States, they’re most commonly found in or around South Florida. Sadly, the American crocodile is registered as a ‘threatened’ species, with a US population of fewer than 1,200 individuals.

The American alligator, also known as the common gator, is the largest reptile in the US and also the largest living alligator in the world (the only other is the Chinese alligator, which is significantly smaller). The American grows to over 12 feet (3.6 metres) in length and weighs up to 1,000 pounds (450 kilos). Males tend to be larger than the females, and the largest reported individual male was a massive 19 feet 2 inches (5.84 metres).

The American crocodile can be a lot bigger, but only outside of the US. Within the boundaries of the USA, these crocs grow to an average length of 12 feet (3.6 metres) and a weight of up to 900 pounds (400 kilos). The largest reported American crocodile in the United States was 14 feet 9 inches long.

South Floridians with crocodile or alligator phobias get a bit of a raw deal, as that’s the one place in the world where both of these species co-exist. Here, the alligators are the dominant species, although the two crocodilians don’t often cross each other’s path. As to who’d win in a fight, the answer is usually the gator, but there’s been at least one recorded instance where an American croc emerged as the winner (although admittedly it was against an adolescent alligator, so the jury’s still out on that one).

Since 2000, there have been 21 reported deaths in the US as a result of alligator attacks, which average at roughly ten per year. The main threat is from their bite, which is amongst the most powerful on the planet. Once a gator has hold of its prey the chances of being released are almost zero, and death from drowning is the usual outcome. The bite also carries a high risk of infection, which can be can be fatal even with medical treatment.

In contrast, crocodiles are typically docile and shy towards humans. According to CrocBITE, the Worldwide Crocodilian Attack Database, there have been 41 fatalities worldwide since 2000, with the bulk in Costa Rica and Mexico. However, zero fatalities have been recorded in Northern America for at least the last 20 years.

Grizzly Bear (Ursus arctos horribilis)

North American Fatalities: On average, there are 2.5 fatalities per year as a result of grizzly bear attacks.

Grizzly bears, also known as simply brown bears, can be found in a large area ranging from Alaska, through Western Canada, and into the American Northwest. Originally known as ‘grisley‘ bears, they were so named for their fear-inspiring character traits, rather than the colour of their hair (‘grizzly’ actually means grey-tipped). But no matter how you choose to spell it, grizzly bears are impressive beasts.

A typical female grizzly weighs in at 300 to 400 pounds, while adult males tip the scales at anything from 400 to 800 pounds. The largest bears are usually found in coastal regions, and occasional huge males have been reported, with weights exceeding 1,500 pounds and a fully-upstanding height of almost 10 feet. Their rapier-sharp front claws measure 3 to 4 inches in length, and they can run at up to up to 35 mph.

Current population figures suggest there are about 55,000 wild grizzly bears living throughout North America, 30,000 of which are found in Alaska. Although this sounds like a healthy-sized population, the US officially lists grizzlies as a threatened species.

As with most wild animals, attacks on humans are rare unless the bear feels threatened, especially if that bear is a mother grizzly looking after her cubs. There has been a lot of folklore based on how to react when you see a grizzly. Some say you should stand still, and others say run, but only if it’s downhill.

Well, we can definitively debunk that theory: you’ll never outrun a bear, so don’t even try. Grizzlies have been clocked at 35 mph, whereas Usain Bolt’s highest recorded speed was 28.35 mph. If even the fastest man in the world can’t outrun a bear, we don’t rate a lesser mortal’s chances. Which reminds us of the old joke: how fast do you have to run to escape a grizzly? Answer: just a little bit faster than whoever you’re with!

In practice, every bear encounter is different and so are the steps you should take. The best ‘what to do’ advice we’ve found is in a great guide published by the National Park Service, which you should read thoroughly if you’re going to bear country. Of course, the best defence is total avoidance, and you can reduce the chances of an encounter by not leaving out any uncovered food, and disposing of garbage in special bear-proof garbage bins.

Bull Shark, Tiger Shark and the Great White

North American Fatalities: Of the 140 alleged shark-human interactions worldwide in 2019, only five attacks were fatal. Florida’s 21 attacks in that year represented 33% of unprovoked attacks worldwide. However, at least for 2019, the number of fatal attacks in the US was zero. Figures for 2020 are yet to be confirmed by the ISAF (International Shark Attack File), but alternate sources suggest at least 32 attacks have been reported in the US, of which two were fatal: one in California, and one in Maine.

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All three of the main man-eating species of sharks can be found off the coast of North America: great whites, tiger sharks, and bull sharks. New Smyrna Beach in Florida is the ‘shark attack capital of the world’ according to the International Shark Attack File. They estimated that anyone who has swum there has been within 10 feet of a shark!

Great whites and tiger sharks “are essentially offshore species that occasionally venture near shore,” says Chris Lowe, head of the Shark Lab in Long Beach, “but bull sharks are a true near-shore species.” In the last few years, bulls have been sighted in the Mississippi River, the Indian River Lagoon in Florida and, amazingly, in the Amazon River, over 2,500 miles away from home.

Carcharhinus leucas, to give the bull its formal name, grows from 7 to 11.5 feet and weighs between 200 and 500 pounds, with an average life span of 16 years in the wild. It’s regarded as the most dangerous of American sharks because it favours shallow coastal waters, meaning it has more contact with humans.

Bull sharks are fearless, which is another reason they’re so dangerous. Mike Heithaus, a shark expert at Florida International University, comments that bull sharks “are one of the few sharks that will tangle with prey that’s the same size or even bigger than them.” Bull sharks (and not great whites) were blamed for a series of attacks in 1916, which served as inspiration for Peter Benchley’s book Jaws. We’re gonna need a bigger boat….

The tiger shark (Galeocerdo cuvier) grows to an average length of between 10 and 14 feet and weighs up to 1,400 pounds, although large specimens can be as long as 25 feet in length. Together with the bull shark, tigers are responsible for most of the attacks that occur off the coast of Florida. Hawaii is typically not included in these statistics, but every attack there has been attributed to tiger sharks.

Tiger sharks are consummate scavengers, with excellent senses of sight and smell. They’re not picky about what they eat, and stomach contents of captured tiger sharks have included stingrays, sea snakes, seals, dolphins, smaller sharks and even license plates and old tires. Unfortunately, humans are also on the menu and, because of their undiscerning palate, tiger sharks are not likely to swim away after biting a human, as great whites frequently do.

Today, the most fearsome living shark is the Great White, which bites with a force of two tonnes. The Latin name is Carcharodon carcharias, which comes from the Greek for ‘ragged tooth’ and is very apt, as everyone’s mental image of a great white includes those horrible snaggly teeth.

The United States has the greatest concentration of Great Whites worldwide, based in the Atlantic Northeast and California, although a few individuals have been recorded off the Alaskan and Canadian coasts.

The great white is notable for its size, with some of the larger females growing to 20 ft in length and tipping the scales at up to 5,000 pounds. According to a 2014 study, the lifespan of great white sharks is estimated to be as long as 70 years or more, well above previous estimates.

The great white is an apex predator, meaning it’s at the top of the food chain with no natural predators. In fact, it’s the only Apex predator alive today that has not been tamed by man. And it would be a brave man who tried it, as ‘Whitey’ has been credited with more fatal attacks on humans than any other species of shark. In California, every recorded shark fatality has been attributed to the great white.

If a shark is on the attack, it’s generally game over for the unfortunate prey. If you want more information on how to avoid shark attacks, and what to do if you’re the one being attacked, we thoroughly recommend the excellent article by Surfer Today, who provide a very detailed list of do’s and don’ts.

It goes without saying that you should never enter the water if you’re bleeding from a wound. This is not because sharks can smell one drop of blood from a mile away (they can’t), but they can sense the direction of blood droplets, which means they’ll probably get to you before you get back to the shore.

The last word on sharks goes to Lindsay French, who manages International Shark Attack File. “We need to remember we’re going into a shark’s natural habitat when we enter the water,” reminds French. “Water sport activities often unintentionally attract sharks because of splashing, paddling, kicking and wiping out. But the number of unprovoked attacks is remarkably low considering the billions of people who participate in water sports each year.”

American Bison (Bison bison)

North American Fatalities: Annual average of 3-5 deaths (estimated)

The American Bison, often known as the American Buffalo, is the heaviest land animal in the Northern US, with males weighing an average of 1,700 pounds. The heaviest recorded male weighed just over 2,600 pounds, and there are legends of bulls that weighed 3,000 pounds or more.

Now, imagine that 2,000 pounds of American prime charging at over 40 miles per hour, and you’ll understand why bison are one of the most dangerous animals you’ll ever meet. Oh, and did we mention they can jump heights of close to 6 feet? So hiding behind a bit of scrubland bush won’t really help.

As frightening as they sometimes can be, the American bison is a respected and revered beast. In 2016 it became the first-ever national mammal of the United States. Way before then, Plains Indians like the Comanche and Arapaho treated the bulky beast as a very spiritual animal. The very rare white bison is regarded as particularly sacred, and one famous white bull was named “Big Medicine” because of its mythical healing properties.

In the 16th Century, as many as a 60 million bison roamed freely across the Great Plains. However, by 1830, early settlers of the West started to systematically destroy the bison in an attempt to deprive the Natives of their rich resource.

This escalated through the 1860s when the new railroad destroyed much of the bison’s habitat, and by 1884 only about 320 individuals remained. Today, the bison population is fairly stable, with roughly half a million living on preserves and ranches, where they are mainly raised for their meat.

Compared to its African cousin the water buffalo, Bison bison has a much less volatile personality, and will rarely attack unless provoked. Safety information from Yellowstone National Park, home to about 5,000 bison, show that bison have injured more people in Yellowstone than any other animal, and there have been two fatalities since the park opened in 1872.

However attacks are increasing, mainly due to people who try to take selfies with a bison. (Yes, it’s true! In June 2020, one 72-year-old woman tried multiple times to take a bison-selfie, standing as close as 10 feet from the animal, which eventually gored her).

So as not to end on a sour note, here’s something amusing. As we’ve stated at the top of this section, our boy’s Latin name is Bison bison. However, there is a sub-species, known as the Plains bison, which has the Latin name Bison bison bison. Presumably so we can be really, really, really sure that it’s not a cow wearing a disguise.

Killer Bees (Mellifera scutellata)

North American Fatalities: Annual average of 62 deaths, from all hornet, wasp, and bee stings. (Separate figures for killer bees are not available.)

Killer bees were a mistake. In 1957, a biologist called Warwick E. Kerr was commissioned by the Brazilian government to come up with a new breed of honeybee. Brazil’s current bees had been imported from Europe, and they had been struggling to be productive in Brazil’s tropical heat. Dr Kerr, whose experience with animal breeding was limited, hit upon the idea of cross-breeding the existing bees with some from Africa. He assumed — quite correctly, as it turned out — that the resultant breed would produce more honey, as they could handle the high temperatures of the Brazilian summers.

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Everthing went very well, at first. Under labarotory conditions, the bees flourished and honey production increased. Until one day, a well-intentioned vistor removed all the screens that had been put in place to separate the queen bees from their worker drones. Within minutes, an estimated 26 colonies — that’s roughly a quarter of a million bees — had been released into the wild.

More powerful and more aggressive, any hope that they would become tamer by breeding with Brazil’s euro-bees was quickly dashed. Instead of cross-mating, raiding parties of Africanized bees attacked the other bees’ hives and killed their queens. This earned them the nickname ‘assassin bee’ in Portuguese. Without any resistance from Brazil’s home-bees, they bred like wildfire and soon swarmed north. By the mid-1980s, they’d made it as far as the US, where they soon become known as killer bees.

Unlike European bees, bred to remove the more aggressive strains over many centuries, the Africanized bees have retained their aggressive nature. Their venom is actually no more potent than that of any other bee: it takes over 1,000 stings for the toxin to prove fatal. However, according to Francis Ratnieks, Professor of Apiculture at the University of Sussex in England, killer bees are more dangerous to humans because “they are more likely to defend their colony in numbers. As there can be 10,000 bees or more in a colony, a fatal dose can occur.”

In fact, the Africanized Bee can react to disturbances ten times faster than a euro-bee, meaning ten times as many stings. And sting they will: if they perceive a person as threat, they will give chase for up to a quarter of a mile (about 400 metres), issuing as many stings as they see fit. Not only that, but once disturbed, a colony can remain agitated for 24 hours, attacking anything that comes near their hive.

But it’s not all doom and gloom. A 2012 study looked at killer bees on the island of Puerto Rico, where they have fewer natural predators. After living on the island for less than 20 years, the bees’ behaviour was notably less aggressive than their US counterparts — proving they can become more docile in the right environment.

Whitetail Deer (Odocoileus virginianus)

Yes, it’s Bambi. The most dangerous animal in North America isn’t the diamondback rattlesnake (0.23 deaths per year), the black widow spider (7 per year) or even a rabid dog (28 per year). It’s the cute, doe-eyed, whitetail deer. They may look the epitome of innocence, but statistically, Bambi and friends are responsible for more deaths than any other animal in the whole of the United States.

But how? They don’t have a venomous bite, they can’t sting, and they don’t tend to charge at you with antlers set to ‘kill’. The answer is car-related, and we’re not talking about road rage.

Each year, American deer cause about 1.3 million car accidents. These lead to roughly 10,000 injuries per year, of which about 200 are fatal. That’s more than all the other animals in this article put together. US Highway agencies have even created a special classification: it’s called DVC (deer-vehicle collision). And it’s worth noting that most of these happen during deer mating season, which is only three months long (October to December).

It’s easy to blame the deer: during mating season, young bucks ‘in rut’ have their eye on the prize (a comely doe) and will run straight in front of your car whilst in pursuit. There are always plenty of road signs to warn of DVCs, but deer can’t read and you can, so it’s not totally the deer’s fault. After all, they were there long before the roads.

FAQs

To save you having to search through countless articles and blogs, here are our answers to the most-asked questions on the internet regarding dangerous animals in North America. You’re welcome!

What is the most dangerous animal in North America?

The most dangerous animal in North America is the eastern diamondback rattlesnake (Crotalus adamanteus). It’s important to note that this snake isn’t the deadliest animal, as deaths from rattlesnakes are a lot fewer than, for instance, the black widow spider. However, it’s fair to say that the eastern diamondback is the most dangerous, at it can inject the most toxic venom.

It’s also uniquely American. So much so, that it was almost chosen as the national animal of the USA instead of the bald eagle. Some authorities believe the western diamondback rattler (Crotalus atrox) is responsible for more deaths overall, but they also concede that the difference is minimal.

The copperhead snake (Agkistrodon contortrix) is responsible for more cases of venomous snake bite than any other North American species. However, its toxicity is among the lowest of all pit vipers and a bite is seldom fatal, which makes it less dangerous than the diamondbacks.

Are there snakes in North America?

There are at least 129 species of snake in the US, classified into 5 families. These are (1) slender blind snakes, (2) boas and pythons, (3) colubrid snakes, (4) coral snakes (including seas snakes) and (5) vipers.

In the USA, there are more snakes in the colubrid family than any other, including water snakes and garter snakes. The viper family is the next largest and includes all of North America’s rattlesnakes along with the cottonmouth and copperhead.

Are there dangerous spiders in North America?

There are quite a few dangerous spiders in North America. Perhaps the most famous is the black widow, whose bite can often cause severe muscle pain, cramping, nausea and mild diaphragm paralysis. This last symptom can make breathing difficult, which is the greatest potential danger.

In the US there are roughly 2,200 reported black widow bites each year, but most do not need medical treatment. According to the latest report from the American Association of Poison Control Centers, the last time a black widow bite proved fatal was in 1983.

Over the past few years, the brown recluse spider (Loxosceles), often known as the fiddleback, has challenged the black widow’s crown for most dangerous spider in Morth America. Whilst its bite is not fatal, it causes necrosis of the skin And leaves an ugly lesion that can take up to three weeks to heal. The fangs of recluse spiders are not large enough to penetrate most fabrics, so on the rare occasion that a recluse does attack a human, the bite often misses its mark.

Summing It All Up

That concludes our look at North America’s most dangerous animals. It’s true that there are a lot of creatures in the US that will kill you, and you’re right to be wary. But, to put things into perspective, worldwide research shows that your chances of being killed by a US animal are roughly 1 in 1.4m. When compared to Africa, where the figure is 1 in 2,200, the odds don’t look so bad.

If you have any comments on this article, or if you’d like to see a ‘most deadly’ article about somewhere in particular, please let us know — we’d love to hear your ideas.

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