Fall is here! Which means leaf colors changing, pumpkin-flavored everything, brisk mornings, cozy scarves and…..rattlesnakes.
Yes that’s right, rattlesnakes, but only for a short time!
So, what do rattlesnakes do in the winter? Animals that can’t produce their own body heat (like rattlesnakes, which are reptiles) need to find a location that can keep them safe during the freezing winter months. Rattlesnake activity will start to increase during the day as they move to find their last meal and go back to their overwintering dens. Last meals are taken 3-4 weeks before entering hibernation in order to be able to completely digest meals while it’s still warm before snakes get too cold and are unable to process food. This will go through the month of October and beginning of November. These dens are called hibernacula (hibernaculum for a single den) and are often in the form of underground cavities in rocky formations or old rodent burrows. These underground locations protect rattlesnakes from freezing and allow them to survive the winter.
Prairie Rattlesnakes (Crotalus viridis) in a natural den.
Another interesting fact about snakes and their hibernacula is that it isn’t uncommon for different species of snakes to use the same hibernaculum for winter. Bullsnakes, racers, garter snakes, and rattlesnakes can all be found in the same den coexisting peacefully (as the world should be) and then go their own ways once spring arrives. Despite the fact that racers are predators on small rattlesnakes and other snakes, there is a truce called during hibernation.
Rattlesnakes will stay in their dens roughly from November to March; however, it isn’t unlikely to see them enjoying those warm winter days just like us!
AES volunteer, Craig, pointing at a natural den where Prairie Rattlesnakes were found.
Adaptation has been on the road this summer! We’ve been to California, New Mexico, and a little closer to home, Southeastern Colorado! Our work in Colorado has been with Colorado Parks and Wildlife (CPW) and their Resource Stewardship team, conducting herptile (reptile and amphibian) surveys. Our goal is to identify the reptile and amphibian diversity at various Colorado State Parks and provide education and outreach materials as well as management recommendations.
In order to determine the different species at any given state park, we employ a variety of methods. Our surveys consist of turtle trapping, walking and searching, natural cover board surveys and road cruising. Natural cover board surveys refers to turning over rocks, decaying logs and leaf litter. However, this is done carefully and with gloves and tools to stay protected in case we flip anything dangerous (e.g. a surprise Prairie Rattlesnake). Road cruising is an important technique because roads hold heat longer compared to other surfaces, this makes it attractive to reptiles who can’t regulate their heat internally and therefore, look for warm surfaces for basking. Furthermore, roads create transects that are easy to survey.
Biological Technician, Norma, with Spiny Softshell Turtle, caught in a funnel trap.
We visited a few state parks this summer, including one in Southeastern Colorado. Our team observed 28 different species by the end of the summer! Some of our exciting finds include, Spiny Softshell Turtles, Green Toads, Plains Leopard Frogs, Great Plains Ratsnakes, a Plains Black-headed Snake, a Longnose Snake, Red-sided Gartersnakes, a Lined Snake, and a New Mexico Threadsnake.
“Herps”, as we like to call them, play important roles in their ecosystems. Some keep prey populations in check, for example, frogs eat insects and snakes eat rodents, which controls the spread of disease. Many herps are also important prey for predators and help keep food webs in balance. A diverse herp population is indicative of a healthy ecosystem. When herp populations are diverse and healthy, this means that the environment they are in can support a variety of wildlife. More biodiverse environments are more sustainable and lead to more balanced, functional systems.
It was very promising to see such a diverse population at the state park. With records of these animals, CPW and park rangers can work together to help protect and maintain these ecosystems and animal populations so many of us can enjoy them for as long as possible.
Coachwhip snake, observed on a survey at John Martin Reservoir State Park.
Wowza, it’s heating up outside! Summertime in (and around) the city presents different issues for snakes. Many people may wonder where all the rattlesnakes are at. Well, it’s a great question to ask and an important one to think about. Don’t worry, the rattlesnakes and harmless snakes are still here and doing their jobs. 😉
Prairie Rattlesnakes (pictured above; aka “nope-ropes” and “buzz tails”) are now more active overnight, or perhaps even late in the day and early morning. Like us, it’s just too hot to be active during the heat of the day. Great, no issues then, right? Well, not necessarily.Overnight, rattlesnakes may hunt for their favorite prey items, which are mostly rodents. If there is considerable rodent activity around your home, then a rattlesnake may find itself near there the area. Be mindful of rattlesnakes seeking cooler areas and prey in places like garages, underneath home foundations and sheds, and near water features. It’s very likely that an area that was snake-free in the evening could now have a snake in the morning. It may stay in this cool place to avoid the heat of the day before moving on again.
What can you do?
Do you have a plan if you or your pet is bitten by a rattlesnake?
For people we recommend following CDC instructions, which we simplify below:
Of course, there are many other kinds of harmless snakes living and working in this area. More common ones encountered are Bullsnakes, Racers, and Gartersnakes (pictured below).
-Photos by Matt Cage and Adaptation Environmental Services
Yellow-bellied racer (above)
Wandering Gartersnake (below)
How do you know if a snake is harmless? Use multiple characteristics to help determine this!
Regardless, we love snakes! You don’t have to. Now you have options.
Need us to help identify a snake in a photograph for you? Share it with us on Facebook or Instagram!
Are you looking for things to do with your kiddos while they are out of school this summer? Viewing wildlife can be fun and educational! Colorado is home to over 400 species of birds, and over 80 species of reptiles and amphibians! Kids can engage with nature, learn how to treat it with respect, and take some cool pictures to show off to their friends later.
Here are 5 places you can visit to see wildlife this summer.
Remember! Anywhere you go:
If you’ve ever bumped into a rattlesnake in Colorado during a summer hike, chances are it was a Prairie rattlesnake (Crotalus viridis). These snakes are the widest ranging venomous snake in Colorado and are sometimes encountered by hikers on trails in the plains and the foothills. Just like people, snakes tend to be more active during the warm summer months, as they rely on higher temperatures to be able to capture prey, migrate and reproduce. With rattlesnake season in full swing, our venom analysis lab at the University of Northern Colorado is hard at work collecting Prairie rattlesnakes from new locations in Colorado. After we capture snakes, we extract venom, dry it down, and process it to understand its composition and properties.
Venoms are complex mixtures containing different toxins that can cause a huge variety of symptoms when a person is bitten. Different species of snakes and even populations of the same species can have different types of toxins because they live in different environments and eat different kinds of prey. Our lab is interested in determining both how and why venom composition varies between species of rattlesnakes found in the western United States.
Most people bitten by venomous snakes in the United States survive because of the effectiveness of antivenom and the fact that medical help is usually readily available. However, it’s important to know the composition of venoms from snakes throughout the country because the effects of their toxins can vary widely. For example, knowing which snakes possess potent toxins that affect the nervous system or those that contain tissue digesting enzymes can help inform snake bite treatment as well as make anti-venom production more effective.
Understanding venom variation can also tell scientists a lot about the history and ecology of a particular snake species. To answer these kinds of questions we need to have a good understanding of what types of animals are typically prey items for a certain species or population. For example, sea snakes primarily feed on fish which is reflected in the toxins present in their venoms that are very effective at killing fish. Rattlesnakes in general tend to feed on small mammals like mice, but will eat whatever they can get, leading to venoms with many different kinds of toxins that can kill prey in a variety of different ways.
The Prairie rattlesnake is not only common in Colorado, it’s range spreads from southern Canada to northern Mexico. Though it has such a large range, we still don’t understand how or why its venom varies. Because of this our lab is interested in studying geographic variation in venom composition since this species lives in many different environments with many different prey items. By separating and purifying the main toxins that make up venoms from snakes in geographically distinct areas, we now know that this species varies in levels of medically significant toxins throughout its range. We see snakes in certain areas with higher amounts of tissue digesting enzymes, while snakes in other areas primarily have potent toxins that affect the nervous system. Knowing these differences can help medical professionals give better medical care to people bitten in different areas. Our study will be ongoing for the next few years, and we hope that our research can answer questions about snake ecology as well as help with snake bite treatment.
PhD student, Venom Analysis Lab
Curator, UNC Museum of Natural History
University of Northern Colorado
Rattlesnake safety is essential if you live or spend time in Colorado, especially in the foothills! Unfortunately, our dogs often encounter rattlesnakes. It is natural for them to inspect and sniff out new smells!
It is best to keep your dog on leash while hiking or walking in the foothills. This can prevent an unpleasant rattlesnake encounter.
Prevention is key here: rattlesnakes are an essential part of the Colorado ecosystem so it is extremely important to learn how to keep yourself and your pets safe while letting the snake be happy and healthy in its natural habitat.
Accidents do happen, so here’s what to look for while inspecting your dog for a rattlesnake bite and what to do if it gets bitten!
Signs that your dog was bitten by a rattlesnake:
If your pup gets bitten:
Though we are lucky to be living near wildlife, it can be scary and unpredictable to come into contact with animals, especially rattlesnakes. It can also feel extremely devastating to watch your beloved dog get hurt.
Remember to breathe, to be proactive rather than reactive. Keep your dog on a leash. Stay safe and enjoy nature!
What to do if you encounter a rattlesnake while hiking
Imagine this- you are hiking in the foothills, your earbuds are in and your favorite summertime jam just came on! Your dog is ecstatic to be outside and is running circles around you. Basically, your day so far, is perfect!
Then, you hear your dog barking up a storm. Something is not right. You pull out your earbuds and start running towards your pup. Low and behold, there’s a snake, basking in the sun, right in the middle of the trail.
You can’t quite tell if it’s a rattlesnake; you’re a bit too far from it and besides the rattle, you’re not really sure what to look for. Panic slowly sets in and your dog is now inches away from the snake’s head still barking and seemingly wound up.
This does not have to be you.
There are a number of simple things you can do in order to better protect you and your loved ones from a rattlesnake encounter while hiking.
We have compiled a list of simple things to do before and during your hike in order to stay safe on our beautiful Colorado trails!
Preparing for your hike:
During your hike:
If you see a snake:
There are many ways to tell a rattlesnake apart from other types of snakes. We will certainly cover those ways in our later blogs. However, we recommend using the above practices for ALL snakes that you encounter in Colorado, just in case!
Prairie Rattlesnakes are the only type of venomous snake species in Colorado. However, just because you don’t see a rattle, doesn’t mean it’s not there. Many people make mistakes when faced with a wildlife encounter.
Follow the simple rules above, stay safe, and most importantly… enjoy nature!
Photos by No Coast Photography
The sun is out and temperatures are finally getting warmer. It’s springtime in Denver, which means it’s time for outdoor activities. I’m excited to be able to go hiking without wearing at least three layers. The thing is... we aren’t the only animals excited for warmer weather.
What do I mean?
Lots of animals enjoy warmer weather and like to take advantage of the sun just like we do, and this includes the Prairie Rattlesnake. Reminder, the Prairie Rattlesnake is the only dangerously venomous snake to live along the Colorado Front Range. So while rattlesnakes can seem scary and dangerous, it’s important to remember that they prefer to not be seen and heard…and only make themselves known when they feel threatened.
It may seem like all of a sudden more and more rattlesnakes are being seen everywhere. This is partially true, since Prairie Rattlesnakes are starting to emerge from their winter dens and will be doing so starting now and into the next 4 weeks. They like to hang out on trails and rocks since these surfaces tend to retain more heat compared to other surfaces. Because of this, don’t be alarmed if you see a snake hanging out on a trail. The best thing to do, always, is to leave it alone and allow it to move on. If you need to get around, leave at least four feet between you and the snake and be cautious of other snakes that make be in the area.
A Prairie Rattlesnake seen in the road. This will be a common sighting during the day, especially in the next 4 weeks. As it gets hotter, rattlesnake activity will eventually increase during the night time.
Prairie Rattlesnake Research with the National Renewable Energy Laboratory (NREL)
With summer comes more research opportunities!
This summer, we are partnering with NREL to provide high quality snake handling training, similar to what a zoo keeper staff would have, so snakes that are found near buildings and walkways can be handled safely.
A rattlesnake being tubed and held by a volunteer. Rattlesnakes are tubed in order to handle them safely without harming the snakes or people.
We will also be continuing our research with rattlesnakes on South Table Mountain. We will be locating snakes that currently have radio transmitters on the NREL campus in order to better understand snake survival and movement when they are relocated. We will also be looking for sensitive habitat so that NREL can help manage these locations.
Volunteer Craig and Project Lead Bryon spot a rattlesnake for potential capture.
Our first date out in the field was April 7th, 2019. We successfully captured and inserted PIT-tags in five snakes that will allow us to determine if snakes found on campus are repeat offenders or the activity is at random.
Successful capture of a Prairie Rattlesnake. They are placed in buckets to keep them safe while waiting to be processed for data.
A snake is probed to determine whether it is female or male.
Jefferson County Open Space (JCOS) Research 2018-2019
We are wrapping up our research with JCOS on South Table Mountain (STM) this summer. Last summer and early fall, we captured rattlesnakes and sent them to VCA Alameda East Veterinary Hospital to surgically implant radio transmitters. This allowed us to track movements and find any winter dens to help preserve and protect those areas. Knowing where rattlesnakes hibernate and prefer to hang out is important information that JCOS can use when planning for potential areas for various park amenities such as parking lots, trail connections and trailheads. We also used these opportunities to educate the public by talking to people we encountered out in the field. This summer we will be recapturing snakes that have transmitters to remove them and after this is done, the snakes will be relocated back to STM. VCA Alameda East Veterinary Hospital is partnering with us to perform the surgeries.
Thank you to our volunteers and partners who made this project possible!
Here are some tips for avoiding any sort of rattlesnake conflict and what to do if you or your pet gets bit.
Reduce your risk of human/snake conflict
Prairie Rattlesnake First AID:
If your pet is bitten:
Prairie rattlesnake spotted on a rocky surface. Trails and rocky areas attract snakes since they tend to me warmer surfaces compared to other surfaces.
Written by Norma Davenport, Lead Research Associate at Adaptation Environmental Services
If you haven’t been paying attention, the summer season is slowly shifting into fall with decreasing temperatures and shortening day lengths. Birders know about these things as they watch migrating birds moving through the state to escape cold weather. Hunters realize that elk and deer will be moving to different areas of their range to avoid deep snow. Perhaps you’ve wondered, “So what do snakes do when the cold weather season approaches?” Because snakes cannot produce their own body heat, they must find a way to stay out of freezing weather until spring. The only place available to avoid freezing is underground, and between now and October, snakes at South Table Mountain will begin the autumnal migration, a gradual movement which directs them to places they know will be below the frost line and give them protection against freezing.
Most snakes enter a subterranean location by mid-November, staying put until perhaps late March, a duration of time called “hibernation”. The location where snakes reside for the winter below the frost line is termed a “hibernaculum” or “den”. Hibernacula (plural of hibernaculum) are critical to the survival of snake species living in temperate zones with cold winters. Without hibernacula, snakes would not survive to reproduce and prey on species, such as rodents, which need the pressure of snakes, birds, and mammals to keep them in check.
One example of a hibernaculum with an entrance under a boulder. Note there are three rattlesnakes visible! Hibernacula are very difficult to identify without snakes present and should remain undisturbed. Photo provided by Derek Carlson
--You may ask, “Now, where would a snake find a suitable subterranean hibernaculum in the vast area of their home range?” Snakes take full advantage of ways to get underground by utilizing rodent burrows of all kinds, such as those belonging to thirteen–lined ground squirrels, prairie voles, and prairie dogs, as well as subterranean passages between rocks that take them deep underground. In areas of their range where hibernacula are not found easily, snakes have learned over hundreds of years or more to use a particular location that supports survival. Up to hundreds or thousands of snakes use this hibernaculum, also known as an ancestral den. In the Front Range area of Colorado, the geologic formations that make up these mountains create large numbers of underground cavities within rocky hillsides that are easily accessed by snakes. Locating a suitable hibernaculum is then relatively simple. Young of the year juvenile snakes commonly follow the scent trail of adult snakes in the fall to discover the best routes to the hibernaculum, or they simply use the nearest rodent burrow and hope that it’s deep enough.
Commonly, several different species of snakes, such as bullsnakes, rattlesnakes, garter snakes, and racer snakes occupy the same hibernaculum during the winter without conflict, and in the spring they all go their own way. With some snake species, such as rattlesnakes and garter snakes, a mild winter day may allow a few individuals to surface at the hibernaculum opening and enjoy the warm sun without exposing themselves totally to predators. Otherwise, most snakes remain underground and out of sight until the warming days of spring begin to heat the soil and rocks, which eventually warms the interior of the hibernaculum and out they come!
Stay safe on the trails as rattlesnakes begin to move to their hibernacula! Photo by Ryan Borgmann
What should you do if you encounter a rattlesnake on a trail?
What should you do if you are bitten by a rattlesnake?
How should you protect your dog?
Here’s our latest look into tracking Prairie Rattlesnakes at South Table Mountain in partnership with Jefferson County Open Space, VCA Alameda East Veterinary Hospital, and the National Renewable Energy Laboratory.
A 2018 research rattlesnake, ST4, on the trail.
As anticipated (and discussed in our previous blog), at least two gravid (pregnant) Prairie Rattlesnake mothers gave live birth to neonates around August 19th this year. The exact number of neonates born this year is unknown, but the average litter size for Prairie Rattlesnakes is 12, however this can vary depending on the age and size of the mother (Hammerson, 1999). Moms stay with their neonates through their first skin shed, which is about 7-10 days after birth. The mothers we are tracking have now moved on to find food before winter.
A neonate rattlesnake born this August to one of our research snakes.
Right now, the neonates are still at the rookery sites, but they may likely be moving on, too. Neonates make a vital push to locate their final meals of the season prior to overwintering. However, some neonates may not be successful. As they move about in search of food, they are easy meals for many predators like birds, skunks, foxes, and even other snakes like Central Plains Milksnakes and Yellow-bellied Racers. (This is normal and neonate snakes are food for other wildlife. In biology jargon, we call this compensatory mortality…and you see this in many other wildlife species such as sea turtles.)
A neonate born this year, see how small it is! An adult is about 3-4 feet long.
Now what? Well, we’re about ready for the final “push” of the season. All snake species will be seeking final meals and start heading back towards overwintering sites. Snakes may start arriving at overwintering dens by mid-September and this continues through October, but some may not arrive until November, which is less common.
This push, along with cooler nights, means that snakes will begin moving more during daylight, increasing the number of snake sightings.
Neonate and mom from our 2017 research project on North Table Mountain.
Notice the rattle "button" on the neonate! Every time it sheds a new rattle will form!
JCOS received two reports of visitor-killed snakes on the trail. Engaging with a snake and leaving a dead snake on the trail is way more dangerous than practicing the 30/30 rule (see below).
This is why killing snakes is not only inhumane, it is also exceptionally dangerous not only to the person killing the snake but also to the hundreds of pets, kids and people that will pass the dead snake after the visitor who killed the snake is long gone.
C.9. Wildlife Protection: It shall be unlawful for any person, or any pet under their custody, control or ownership, to harass, chase, harm, capture, kill, maim or possess any wildlife including, but not limited to, mammals, birds, reptiles, amphibians and fish on Open Space Lands. Fine: $300.00
What should you do if you encounter a rattlesnake on a trail?
What should you do if you are bitten by a rattlesnake?
How should you protect your dog?
The latest look at the rattlesnakes we are tracking on South Table Mountain!
Photos by Ryan Borgmann
Adaptation Environmental Team: Bryon, Joe, Kelly, Norma and Ryan