The 9 Most Dangerous Animals in Colorado to Watch Out For

Although the Coloradan wilderness is pretty picturesque, hidden amongst the evergreens and blooms, it’s also home to a number of species that can quickly become dangerous animals when threatened. Some studies even suggest animal attacks in the state have become more frequent in recent years, with human influence causing more unusual changes in animal behaviour year after year, according to local rangers.

Four of America’s most envied national parks fit inside the state’s borders, all with their own collection of wonderous wildlife. Sheep, elk, deer and hundreds of birds can be spotted in the meadows and grasslands, but the deeper you delve, the more dangerous creatures you may encounter.

Before venturing to this relatively untamed region of the United States, it’s important be prepared – knowing your moose from your mountain lion may seem obvious, but both can prove problematic if you’re not careful! So, we’ve collated a comprehensive list of dangerous creatures you should keep a look out for when travelling in Colorado, and how to prevent yourself from being attacked by any of them.


A rattlesnake in mid strike

Despite their somewhat scary appearance and unruly reputation as reptiles, many of the snake species residing in Colorado are actually non-venomous. Rattlesnakes are the only venomous snakes in this scenic state, and therefore, the only species that could potentially be dangerous to humans. Distinctive features in their appearance including two upper fangs in their mouth and triangular-shaped heads can often help you identify these particular snakes in the wild. But, if you do happen to encounter one while exploring Colorado’s remarkable foliage and gloriously green mountain ranges, follow the simple guidance of staying calm and avoiding any quick movements to avoid receiving a nasty bite or an injection of venom.

Does Colorado have poisonous snakes?

As mentioned above, the only venomous snake in Colorado is the rattlesnake, with three species known to live in the state: the Western massasauga rattlesnake, the midget faded rattlesnake and the prairie rattlesnake. Although they have the ability to seriously injure humans, these snakes are only prone to being aggressive when provoked – so leave them to enjoy the wilderness alone and you should be fine!

Mountain Lions

Mountain Lion sitting on rocks

It’s not unusual to hear locals pre-warning those going hiking in Colorado of the risk posed by Mountain lions. These common, tawny coloured cats – also popularly known as cougars – typically prefer to avoid any human contact, happily wandering through the verdant forest and foothills as they prey on deer and elk. However, upset any mountain lion when passing through their rightly claimed territory and you could find yourself in a challenging position. If you do encounter mountain lions in the wild, it’s best to stay well back to prevent any form of attack; make loud noise by yelling or shouting and slowly create distance by moving further away from the animal, never turning your back.


Coyote in the wilderness

With their pointy ears and bushy tails, it’s easy to think of coyotes as being cute — but don’t be fooled, these grayish brown-coloured natural predators can run up to an astonishing 40 miles per-hour and will be relentless in protecting their young and their territory. The animals are active day and night in both urban and rural areas of Colorado, often heard in canine chorus as they hunt for food in larger packs during the winter months, although you’re more likely to encounter a solitary animal in the wild. As they’re naturally timid and often startled by people, a coyote may simply pass you by with no sign of aggressive behaviour or attack. However, if you are approached by one or more coyote, you should deter them by being as big and loud as possible — throwing small stones or sticks towards the animal may work if they refuse to react to any noise.

Are there wolves in Colorado?

According to Colorado Parks and Wildlife, wolves were eradicated from the state by shooting, trapping and poisoning in the 1940s. However, lone wolves have been spotted travelling in and out of state in recent years, meaning there’s potential for new packs to form and reside in the surrounding wilderness in the future.

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Moose in the bushes

Until two decades ago, moose were a rare sighting in Colorado, which may be hard to believe considering the state’s moose population now exceeds 3,000 according to research. Recognizable by the sight of their enormous antlers, the largest member of the deer family can be found grazing on higher grasses, with State Forest State Park named the official ‘moose capital’ of Colorado. Although they may look like harmless mountain residents, moose can be unpredictable, aggressive and dangerous animals — more people are attacked by moose than by any other wild animal every year. However, follow the simple precautions of maintaining safe distance and allowing moose ample space to pass by and you shouldn’t encounter any run ins with these heavy hoofed herbivores.

Black Widow Spider

Black Widow spider on a web

An infamous name in the spider kingdom, the Black Widow has become a fearsome sight for those unfond of eight-legged creatures. Only females actually pose any threat to humans, identified by their shiny black body with a red, hourglass-shaped marking. The bite of a Black Widow can be extremely painful, with their venom over ten times more toxic than a rattlesnakes and sometimes causing serious reactions with long lasting effects. Whilst travelling in Colorado, watch out for these dainty but dangerous animals in sheltered, dark and undisturbed areas, and make sure to seek medical assistance if one does happen to bite you.

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Which spiders are poisonous in Colorado?

In addition to the fearsome Black Widow, other known venomous spiders in the state include the Hobo Spider, Yellow Sac Spider and Brown Recluse Spider. Their venomous bites can cause symptoms varying from mid headaches and blistering, to localised swelling and wounds with particularly long healing times, so it’s best to steer clear of these not-so-friendly creepy crawlies if you can.


Bull Elk in the wild

Colorado boasts one of the biggest elk populations in North America, even though hunters from around the world regularly travel to the state to pursue the creatures and threaten their existence. You’ll regularly catch a glimpse of elk in Rocky Mountain National Park and Colorado’s National Forests, where the gregarious grazers can be found enjoying seemingly endless shrubs, plants and grasses. Though they may not appear threatening at first glance, the unpredictable elk can make aggressive advances when you least expect it — females can be protective of their young, while males are known to attack more during mating season. Avoid being charged by an elk by keeping your distance and using binoculars for a closer look!

Black Bears

Black bear in the forest

Although black by name, these brazen bears that call Colorado home are typically blonde or brown in colour. It’s been estimated there could be up to 20,000 black bears living in the state in recent years, with the Rocky Mountain National Park proving one of their favourite habitats. The male bears usually come out of hibernation in March to feed on the blossoming berries – shortly followed by the females and their newborn cubs – and stay above ground exploring the wilderness until late October or early November. These wild animals are usually harmless and often scared by the sight of humans, however, they can quickly become aggressive when it comes to protecting their young. Human food left after picnics or at campsites can also change bear’s eating habits, and in turn, change their behaviour. So, it’s best to leave their natural habitat as you found it to avoid any dangerous confrontations.

Are bears dangerous in Colorado?

The number of bear attacks reported involving humans here has remained low in recent years, with the last known fatal attack involving a human and a black bear was in 2009. A bear’s envied sense of smell can sniff out food from up to five miles away, so if they do decide to approach, that’s likely to be why! Keep your tasty snacks in air-tight containers and make sure to leave no litter to deter them from hunting down any leftovers!

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Does Colorado have grizzly bears?

There are no longer any grizzly bears in the national parks of Colorado, or in the entire state in fact – they were declared as locally extinct in 1953. The brown-coloured bears were happily thriving in the remote Rocky Mountains for many years, until the population plummeted due to hunting. Known for having a violent reputation, their disappearance from the area means it’s one less dangerous animal you have to worry about!


Tick on a green leaf

Tick season in Colorado starts in March, and if the weather’s more moist than usual, you can expect an influx of these tiny but troublesome creatures. Common Colorado ticks typically live in the warm fur of animals including elk and deer, but they can also be found thriving alone in naturally wet areas including fields, marshes and woodland. Many humans encounter a nasty bite from these critters when hiking in Colorado after they’ve attached themselves to clothing or equipment, usually going unnoticed until it’s too late. The simple solution? Grab yourself a pair of tweezers and pull the tick directly away from your skin — as a general precaution, it’s also best to see a doctor to double check there’s no serious infection post-bite.

Mountain Goats

Mountain goat standing on rocky hillside

Although they’re not native to Colorado, mountain goats have become one of the most commonly sighted animals meandering through the mountains. They’re happy to spend most of their time alone on the state’s lush higher terrain, but in recent years, experts have noticed an increasing trend in unnatural behaviours in mountain goats. From climbing on top of cars to charging into people’s picnics, it’s thought these wild animals are becoming more heavily influenced by humans year after year. To avoid getting too close to the creatures and making the goats feel threatened, it’s best to stay away; attacks are more likely if you’re invading their space, or if you’re lingering around for too long for their liking.

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So, what is the most dangerous animal in Colorado?

Majestic mountain lions are commonly regarded as Colorado’s most dangerous animal, but according to the CPW, it’s very rare for these lions to attack humans – there’s been only 22 attacks on people in Colorado since 1990. All of the iconic wildlife in our carefully compiled list is worth looking out for when you’re travelling in and around Colorado, but many are only known to attack when threatened, or in the position where they need to protect themselves or their young. As long as you respect the sometimes unspoken rules of the natural world, you should bee free to enjoy this spectacular state without any worries.

Mountain Lion - one of Colorado's dangerous animals - on rocks

So, have you already started excitedly planning your trip to explore this state’s long-loved landscapes? Here’s some easy-to-remember rules! This simple but important advice should help you when it comes preventing wild animal attacks or signs of aggression:

  • Keep your distance – animals appreciate their space, so don’t tread to far into their territory or try and get too close for comfort
  • Follow posted signs and advice – stick to the footpaths and you should avoid any areas that have been identified as potential attack zones
  • Travel in a group – you’re always more vulnerable alone, so make sure to bring along others who also understand the important of respecting dangerous creatures when heading into wild
  • Stay calm – if you do end up unexpectedly close to a bear, mountain lion or any other potentially dangerous animal, it’s best to keep your composure. Don’t show any sign of fear and apply common sense to the situation!
  • If under threat of attack, make noise – some wildlife featured in this list are actually startled by humans and loud noise, so shouting, yelling or banging loud items together can deter them from pursuing you and your group. However, don’t try this tactic with coyote as they can become irate when threatened or intimidated, while your best bet with mountain lions is to move away slowly without turning your back

James Ardimento has spent the last 12 years journeying around the globe ! With its precious experiences and tips he gained around Asia, South America, Europe and the US he is a precious asset for this blog and for its readers