Colorado Rattlesnakes: What Sportsmen Should Know

Colorado is home to about 30 species of snakes. Of these, only three snakes are a risk to humans: the prairie rattlesnake, the Western rattlesnake and the massasauga rattlesnake.
A prairie rattlesnake in Morgan County
A prairie rattlesnake in Morgan County. Prairie rattlesnakes are the most common and the largest rattlesnake in Colorado, reaching sizes of 3.5 feet in length.

Springtime in Colorado is a great season. The warm days provide a glimpse as to what lies ahead, while the cool nights remind us that winter hasn’t retired quite yet. It’s also a time when nature begins waking up; leaves bud out, migratory birds return and (my favorite) the reptiles reappear.

In fact, I had my first report of a snake just a couple weeks ago. Amazingly enough, the e-mail arrived during a spring snowstorm, though, the picture was obviously taken days earlier in the warm sunshine.

This particular identification was easy: a young-of-the-year racer, really no bigger than a typical ink pen. Although most of Colorado’s snake species pose no threat to humans, I’ve been working with snakes and educating the public long enough to know not everyone believes this to be true. And because of their appearance, snakes evoke fear in many people, which almost always is unwarranted.

A young-of-the-year racer snake.
A young-of-the-year racer snake.

Colorado is home to about 30 species of snakes. Of these, only three snakes are a risk to humans: the prairie rattlesnake, the Western rattlesnake (also known as the midget-faded rattlesnake) and the massasauga rattlesnake. Do you see the pattern here? The only venomous snakes native to Colorado are rattlesnakes.

Prairie rattlesnakes are abundant and are found statewide in nearly every type of habitat (prairies, foothills, riparian corridors and towns/suburbs) below 9,000 feet. The Western rattlesnake, hence the name, is found west of the Continental Divide, primarily along the Colorado/Utah border. The third species, the massasauga, is a small rattlesnake localized to the sandy terrain of southeastern Colorado.

So as we humans change our routines from winter outdoor pursuits like ice fishing, skiing, and competitive hot-chocolate drinking, to spring fly fishing, turkey hunting, hiking and general vitamin-D replenishment, we have more chances to bump into a rattlesnake or two.

Meeting a snake on the trail to your favorite fishing hole or hunting spot is not a huge cause for concern, if you remember a few safety tips and understand snake behavior.

1. Rattlesnakes Prefer to Hide

A Western rattlesnake
A Western rattlesnake, also known as the midget-faded rattlesnake, takes cover along a rocky ledge. Hence the name, this snake is found in western Colorado along the Colorado/Utah border. Photo by Stephen Mackessy.

Rattlesnakes are cryptic and use camouflage as their first line of defense. They would rather hide than interact with humans or other animals. Because of their coloration, most rattlesnakes blend in with their surroundings exceptionally well. In most cases, they will simply ignore you, thinking that you cannot see them. However, if the snake coils up and rattles, you are too close and should move away slowly. Stepping back just a few feet can be enough to convince the snake that you are not a threat. Most rattlesnakes will not strike at people unless they feel threatened or are deliberately provoked.

2. Don’t Touch Any Snake

massasauga rattlesnake
The massasauga rattlesnake is found in the sandy terrain of southeastern Colorado. Photo by Stephen Mackessy.

Even though only three of our native snakes are venomous, all snakes have teeth and know how to use them. Regardless of the species, it’s a good idea never to handle any snake. Contrary to popular belief, snakes don’t need to be moved off a trail or “helped” anywhere, although, a snake using the road as a heating pad might appreciate some coaxing to the shoulder. Most people get bit on the hands, so you can limit your chances by keeping your digits out of range.

3. Watch Where You Put Your Feet and Hands

Remember: Snakes like to hide. So on rocky trails or areas with downed trees, be sure to check what’s on the other side before putting your appendage there. It’s also a good idea to avoid hiking in tall grass where you cannot see what’s lurking below. Move slowly and use a walking stick to check what lies ahead before stepping forward. A pair of snake-proof boots or high-top hiking boots can provide additional protection if you are walking in known rattlesnake country. When hiking, it’s also best to leave the iPod at home so you can hear a snake’s warning rattle.

4. Keep Dogs Close to You

Dogs are curious and snakes are defensive—a bad combination. Unfortunately, a snake isn’t going to take the time to determine if that large, canine nose headed in their direction is a curious domestic dog or a wild coyote or fox that is searching for a snake dinner. On hiking trips, you should keep dogs on a short leash. Hunters using bird dogs should be especially mindful of rattlesnakes during dove season and the early part of pheasant season prior to the first winter freeze. Training your hunting dog to avoid snakes may also help prevent bites. Although somewhat controversial, some veterinarians are now administering a rattlesnake vaccine, which can help minimize the effects of a snakebite. It’s best to check with your veterinarian for recommendations, as opinions and treatments vary. If a dog gets bitten, it’s important to seek veterinary treatment as soon as possible.

5. If You Get Bitten by a Snake, Don’t Panic

As mentioned above, most snakes in Colorado are not venomous. But no matter what species administered the bite, the best option is to have it looked at by a doctor. Don’t try any of the Western remedies you’ve heard about like cutting open the bite and attempting to suck out the venom. Leave the bite alone and seek medical attention as quickly as possible. The best “first-aid kit” for a snake bite is your cell phone and car keys. If possible, call ahead to the medical facility so doctors can be prepared with the appropriate treatments.

6. Remember: Snakes Benefit Our Ecosystems

A bullsnake coils to defend itself.
A bullsnake coils to defend itself. Bullsnakes are often mistaken for rattlesnakes because of their ability to mimic rattling sounds by shaking their tail. Like other snakes, bullsnakes help manage rodent populations.

All snakes, including rattlesnakes, play an important role in balancing our ecosystems. Snakes eat rats, mice, prairie dogs, and they help control insects and other “pests.” Snakes also sit in the middle of the food chain, providing food for raptors and other predators. Respect and enjoy snakes when you see them in the wild.

By taking these simple precautions, it will help ensure that your time spent in the outdoors this spring and summer is both safe and enjoyable.

This article was written by Tina Jackson. Jackson is the species conservation coordinator for Colorado Parks and Wildlife. She became fascinated with snakes in childhood and has spent the last 10 years learning about snakes and sharing her knowledge with others. 

53 Responses

  1. I did really enjoy the article . You did put out some good information. I do have to take exception to one thing though. I grew up in the area West of Loveland and spent hundreds of hours hiking camping and generally exploring. The most common Rattlesnake in that area I agree is the Prairie Rattlesnake. I can assure you though that there are Many Large Diamondback Rattlesnakes in Colorado though I do not know which species. I know they are common in the Masonville to Horsetooth Reservoir area as well as the lower Buckhorn road area. If anyone cares to verify this please feel free to travel any of the roads in that area after dark. I am quite sure you can find local residents to verify this. I have witnessed many in the 4-6 foot range and have heard of much larger specimens. Some approaching the 8 foot range. My Dad personally witnessed a snake that stretched nearly the width of the traffic lane and as big around as a motorcycle tire. That was in the 70’s on the road around Horsetooth Reservoir.

    1. As mentioned by Jerry, none of the “diamondback” rattlesnakes (C.atrox, C. adamanteus, C. ruber, etc.) are native to CO, and indeed would not be capable of surviving here as they are more southern, warm-climate species in all regards. Additionally, the largest prairie rattlesnakes rarely exceed five feet in length (historical records as well as personal correspondence with Dr. Mackessy who took some of the photos in the article), so if what you saw was bigger, it wasn’t a rattlesnake; bullsnakes may appear similar to someone who only catches a glimpse of the animal or doesn’t have a great amount of experience, and large specimens of those can exceed 7 feet in length. Otherwise, larger snakes are not present in CO, and if you saw something greater than in that range it may well have been an escaped or wrongly released pet (which likely won’t survive a winter here so no need to worry whether it was venomous or not).

  2. Brad, I’m glad you enjoyed this post. Based on historical data, Diamondback rattlesnakes are not found anywhere in Colorado. What you are likely seeing are large Prairie Rattlesnakes, which have some similar features to Diamondbacks. The areas you mentioned are common to Prairie Rattlesnakes. However, you are always free to e-mail Colorado Parks and Wildlfie photos of any snakes that you may have questions about. Thanks again for your comments.

  3. Hi Tina, Great article. Do you have any rattlesnake population numbers or statistics for Colorado? I am specifically seeking info about the area in and around Sterling. TY

    1. Michael, I spoke with Tina Jackson and here was here reply: “Colorado Parks and Wildlife has not conducted any population monitoring for rattlesnakes, so we do not have any specific numbers for how many snakes are in the state. However, we do feel that the populations are doing quite well (hence why we allow them to be taken as a game species).”

      Thanks for your question!

  4. I’m nervous around any snakes that I’m not CERTAIN are non venomous; I felt really bad a few years ago–I was stopped while on my motorcycle by a large snake sunning itself on one of the county roads west of Loveland. I wanted to move him from traffic, but I didnt know enough about reptiles to know if he was dangerous. While I was trying to work that out, he was run over by a car and killed. In retrospect, I found out it was just a bull snake.

    1. Alex, Thanks for your comments. It always best to keep your distance and treat all snakes with respect. It’s too bad that this bullsnake got ran over. They are a great asset at controlling our rodent populations. Thanks for reading this post.

  5. I think it is important to note that adult rattle snakes release venom only 10% of the time when they strike in a defensive situation. Venom is metabolically expensive for a snake to produce and they much prefer using it for prey. A baby snake however will release a full dose of venom as they have yet to develop muscle control over their venom glands. This is why very small, young rattlers can be the most dangerous to receive a bite from.

    1. Jim, not true at all. No one has ever been able to nail down an actual statistic on the relative occurrence of wet vs. dry bites (in other words, it’s luck of the draw), but current estimates put the range of wet bites at anywhere between 30 and 80%, far higher than a measly 10. They would prefer using it on prey, and adults will release less (on average, not always) than juveniles, but it still occurs more often than that. Also, young rattlesnakes have every amount of control over the amount of venom injected, if perhaps not the experience to always regulate venom dosage, but even a baby rattlesnake delivering all its venom would not come even close to the venom delivery of even a portion of a full grown snake’s stores, so no, they are not more dangerous. Better to say young and old are all equally to be respected.

  6. However, we do feel that the populations are doing quite well (hence why we allow them to be taken as a game species).”
    Am I reading this correctly? You allow people to hunt reptiles? Why? What do they do with them?

    1. Thanks for your question. Colorado allows two reptile species to be taken as small-game species: prairie rattlesnakes and the common snapping turtle. Both species are eaten, and snake skin is also used like leather. We don’t anticipate that hunting has much impact on the population because so few hunters actually participate in this season. Colorado also allows rattlesnakes to be taken to protect life and property (dogs, livestock), which is likely a much greater number than snakes harvested by hunters. Thanks again for taking the time to read this blog.

  7. Very informative article. I live in eastern CO east of Colorado Springs. The ranchers out here kill most snakes even though they keep down the rodent population. I will throw dirt at a snake if it is on the dirt roads out here to keep them from getting hit. Works very well. All of nature is a balance which we humans do our best to screw up.

    1. Kelly, thanks for your comments. I think many folks have an irrational fear of snakes. All too often, snakes are killed unnecessarily (and illegally) when they post no threat to human safety. Like all wild animals, snakes should be respected and enjoyed from a safe distance. But it’s important that people realize the important role they play in our ecosystem. Thanks again for checking out our blog.

  8. Interesting to read this article today just after returning from a local Littleton fishing trip along the urban South Platte River just downstream from Chatfield where I encountered my first snake of the season, a forty or so inch common garter snake, two feet from the river.

  9. This is ridiculous. Many of you people obviously do not have pets or family members that have been affected by these snakes. I do not mind nonvenomous snakes. Rattlesnakes should be taken out when seen. Trust me, they’re still be plenty left at the end of the day. And if not, there are lots of other species to take out the rodents and feed the birds. Rattlesnakes are dangerous to you, your children, your pets, and livestock. City people just don’t get it…. I look forward to the replies! Have a wonderful day! 🙂

    1. Totally agree–worry about my dog. Had him snake proofed by some group in Franktown area—they used Texas diamond backs—worthless exercise as we only have the prairie rattlers. Shoot every one I see–sorry.

  10. There’s a season, mid June through mid August. I saw a large rattler in the road last spring but I hesitated to harvest, good thing, when I got home I looked it up.

    Snake tastes delicious. My favorite recipe is to singe it over a fife then scrape scales off with a sharp knife. Boil lightly for just a minute then remove, let cool, flake the meat off the bones with skin intact, toss meat when cool with fresh mint, toasted crushed sticky rice, fresh squeezed lime. Bones go back in the soup and boil for further 10 min, add kafir leaf, tomatoes, cilantro. Eat with rice on side.

    1. I think your spice and vegetable choices sound tasty enough for me. I am not a huge fan of rattlesnakes but I don’t think we are so taxed for food choices that we can’t avoid eating them for anything but absolute necessity should the situation arise. (It rarely does). Just my thoughts.

  11. Hi,

    i have donkeys and some weeks back, thought I heard a hissing in the hay stack in the barn. We removed all the bales and restacked them.

    This afternoon as I entered the barn there was a prairie rattler, I believe coiled against the wall on top of a bale. i was several feet away and once it spotted me, it turned and scooted behind the bail. Over the years there have been numerous sightings, but never in the hay before.

    I am a little concerned about what to do next. I will exercise care while feeding but I do need to handle the bales to feed the animals. I would like to discourage it from the area. .

    Any suggestions? Thanks so much. I enjoyed your article.


  12. Thanks for the informative article. I will be visiting Colorado soon from the Upper Midwest. I plan to hike on mountain trails with my two dogs and thought 6-foot leashes and my and their alertness would help protect us from rattlesnakes. But a few weeks ago, they ran right past and in the case of one dog, over, a garter snake TWICE without even noticing it! They didn’t see it (it was halfway in the trail sunning itself) or smell it. So now I’m thinking they could do the same with a rattlesnake (unless it rattled). It makes me wonder whether snake camouflage includes an odor that blends with the landscape? Also, I would be interested in hearing from rattlesnake-savvy dog owners about how they keep their dogs safe on hikes. We have hiked in wolf, moose and black bear territory (never saw one) and timber rattler territory (saw one once without my dogs) but are greenhorns when it comes to the Rockies’ rattlesnakes. Thanks!

  13. Hi! Luv the post. I run a lot on table top mountain and almost stepped on several rattlesnakes & had a few close calls and am grateful for their warning rattles But I was wondering if there’s a better time to run than not? I don’t mind the snakes but don’t want to get bitten 😉

    1. Lex, Thanks for your comments and questions. The short answer is it depends on the ambient temperature. Obviously the safest time to hike is when the snakes are hibernating. During the summer season their activity changes with the daily temperature. Snakes will be active during the heat of the day and look for shelter during the cold nights. But during the hottest parts of summer they will shift their activity to the cooler parts and seek shelter during the heat. The key for ectotherms is to stay in that ideal temperature range, which is different for each species; So the best advice is to GENERALLY avoid the sunny trails when it is cool and the shaded areas on extremely hot days. As mentioned in the article, it’s best to hike or run without ear/head phones, as you want to be able to hear a snake’s warning rattle if you get too close.

  14. I was hiking in El Dorado on Monday and came across a rattlesnake just off the trail in the grass. It was more of a light jade green color than the expected brown/yellow. It rattled to let me know that it was there so I moved to avoid it. Is this a common color?

  15. Thanks for the article. I read it with my young boys but we are still having trouble identifying a snake we found in our well pit. Do you have any suggestions to help with identification?

  16. Nice Blog. I had the pleasure tangling with a prairie rattler in a wrecking yard a few days ago. I came across your blog while trying to better ID the snake. The snake I stumbled onto was about 5′ long and had a striking range of between 5 and 6 feet and at the widest point was big as a fencepost. I have been around rattle snakes most of my life, but I have never seen a snake as large or as aggressive as this one. It was in Full-On attack mode from the get go. It did not rattle or hiss before striking, and were it not for the unusual green color, I would never have seen it coming. My question for you is this: Would you happen to know the size of the largest prairie rattler ever recorded in Colorado? With all of the rain over the summer, it appears that these snakes may have had a record year in 2015. Again Thanks!

    As an aside: Folks traveling in Southern Colorado might want to keep their eyes open when stopping along side of the road, changing a flat tire, making a pit stop, walking a dog, rock hunting, visiting roadside parks, rest stops, or even when conducting a Chinese fire drill, etc.. Best way to get out of trouble with these bad boys is to get out of trouble before you get in. As for me; I was caught off guard. I had to go to “Plan B”.

    “Plan B” might best be described as a weird combination of a Goose Stepping Mexican Hat Dance followed by an Electric Slide and finally breaking into a River/Brake Dance. And for the record; I “Do NOT” recommend that anyone try “Plan B”. ( Needless to say, the snake was much more accomplished at all of these dances than I will ever be.)

    As a rule; It is always better to quietly and slowly back away from a snake. However; As previously stated, this was the largest most aggressive snake I have ever seen. I believe it must have been the Green Colorado Prairie Rattler known as ……………… SnakeZilla!

  17. Hi, I wanted to ask (forgive me if asked already) but can rattlesnakes be a danger to those swimming in lakes??? (Specifically horsetooth) I have a friend that works for the county and literally showed a picture of a large rattlesnake that swam up to and on a boat! We love to kayak horsetooth and swim, but can they really be swimming in the lake, depths, and feel threatened enough/or be able to bite in water? Seems unheard of and so I wanted to clarify. Thanks for your help!

    1. Rachel, Thanks for your question. Most snakes are able to swim and we hear of snakes in the larger reservoirs climbing on to boats, likely because they got further out then they expected and need a rest. Just like on land, a swimming rattlesnake is going to protect itself if it feels threatened. So, I would suggest giving a swimming snake plenty of room and not try to touch it or pick it up.

  18. The author of this article, Tina Jackson, receives an F grade for posting incorrect info on Colorado’s rattlesnakes. The Western rattlesnake, Crotalus viridis, also commonly known as the Prairie rattlesnake, is the most common rattler in Colorado and is found EAST of the Continental Divide statewide below elevations of 8500 feet. The range of the Midget Faded rattlesnake, Crotalus viridis concolor, is limited to the Colorado Plateau and has only been documented in the western counties of Moffat, Rio Blanco, Garfield, Mesa, Delta, Montrose, and San Miguel. Colorado Parks and Wildlife shouldn’t be very pleased that someone with the title of species conservation coordinator can’t furnish accurate wildlife info that takes very little effort to document. Very careless or lazy or both.

    1. Mike, Colorado Parks and Wildlife is following current taxonomy (since ~2003) which splits Crotalus viridis (prairie) and Crotalus oreganus concolor(midget faded); concolor is no longer accepted as a subspecies of viridis. There are some in the community that believe this will change again but it is the current standard. Thanks for reading. However, no need to be so “venomous” with your comments. We always do our best to edit for accuracy and provide the best information.

  19. My family often frequented Horsetooth Reservoir, as well Sterling Reservoir amount several others in E. CO, for water sports in the early to mid 60s, often saw rattlesnakes on the ridges particularly the East side of Horsetooth, but never in water even during the hottest weather, Sterling reservoir is another thing! One summer, we were waterskiing and came on something we’d never seen, a large grouping of rattle snakes in the water. The day was Very Hot, as well as memorable! My dad who was driving our boat, later said they looked like a ball of fence, and were definitely swimmers. Needless to say, they were safe from us, we never returned!

  20. Just curious if you could tell me how and if a Colorado rattle snake could travel to Utah because I know that’s what type it was the pattern matches to a tee it was not your typical western rattler

  21. 8/9/2018 I would LOVE for a rattle snake hunter to contact me and hunt these things off my property. Yeah, yeah, yeah… the ecosystem. I have horses and I can’t ride or relax knowing I built my dream house and barn in an infested community. I’m SERIOUS and so are my neighbors!

    1. I’m just wondering where you built because I found this article searching for a map of the most heavily rattlesnake infested areas of Colorado. I’m planning to do the same as you (build a home and barn on a piece of land) and I know they can be about anywhere, but want to avoid them as much as possible. Thanks in advance.

  22. I have a place west of Alamosa. Lived here for 25 years, elevation 8800 ‘. No snakes—last 4 years— they are showing up–I have dogs. Worries me killed 7 in the last 3 years. Why are they showing up now ??

  23. Good write-up, but you forgot the Massasauga. Not very popular in knowledge, but very abundant in numbers in the SE part of the state.

    1. The author both mentioned and pictured the Massasauga in the article:

      Colorado is home to about 30 species of snakes. Of these, only three snakes are a risk to humans: the prairie rattlesnake, the Western rattlesnake (also known as the midget-faded rattlesnake) and the massasauga rattlesnake. Do you see the pattern here? The only venomous snakes native to Colorado are rattlesnakes.

  24. Folks, I worked in a venom research lab in grad school. I know snakes. I have seen a couple of western diamondback snakes in Colorado. Once you stumble on one, you never forget it. They don’t act like prairie rattlers. They are a very very aggressive snake.

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