Most zoos are known for their diverse collections of animals from many countries for education, conservation, and the WOW factor. Zoos maintain a diverse collection of reptiles and amphibians, which includes venomous snakes from around the world. A great deal of responsibility is inherently required when a facility houses highly venomous snakes in a public setting.  You can imagine that the safety factor needs to be ramped up to prevent escapes and therefore potentially deadly venomous snake bites to members of the public, as well as zoo personnel charged with caring for these snakes. How do zoos maintain a high level of safety?  Let’s look at a typical set up.

In order to receive venomous snakes and house them in enclosures, zoos must have all of the necessary permits and inspections from various agencies assuring the public that all safety -related processes are being met. Simply receiving venomous snakes from delivery requires super safe containers that have redundant containers within containers.  Explicit labels to identify container contents and displaying caution colors to avoid accidental unauthorized opening is always present. After safely opening the container, snakes are transferred to enclosures in a quarantine area to prevent any possibility of contagious diseases spreading to the main collection.  Once cleared from quarantine, snakes are moved to exhibit enclosures.   It is worth noting that in order for a zoo to maintain a venomous snake collection safely, part of their planned safety protocol is to keep antivenin at the zoo for each venomous snake for which antivenin is produced. Antivenin is kept in a refrigerator at all times and is replaced before it expires.  Having antivenin on hand speeds up the response time to treat a venomous snake bite.  Training zoo personnel to work with venomous snakes requires a process of repeated training to respond to a bite.  Usually involving the entire staff in a snake facility, this process involves activating an alarm that sounds throughout the building to identify where the snake bite has occurred, enabling a faster response to the bite victim. The bite victim typically would remove the species identification tag from the enclosure and secure it to his body in case he becomes unconscious and is not able to identify the snake species involved.  First aid at the onset may depend on the snake species involved.  For example, a cobra bite may need a moderately tight compression wrap on the bitten extremity to impede venom flow while the bitten person is transferred to a hospital.  Additionally, antivenin for that species is also transferred with the zoo personnel to the hospital. Antivenin must be given only under the charge of an experienced doctor under controlled conditions.

Handling venomous snakes safely requires specially designed tools that are essentially extensions of our arms and hands. Snake handling requires safety training initially with non-venomous snakes for personnel new to snake handling. Training in the safe use of hooks and tongs and combinations of these tools goes hand in hand with the use of specially designed transfer containers used to temporarily house a snake while exhibit enclosures are maintained. 

​Advanced training for venomous and non-venomous snake handling also incorporates the use of transparent plastic tubes in which a snake is encouraged to enter but restrained in a way that traps the snake inside the tube, preventing the head (and thus, the fangs) from extending beyond the tube.  Tubing a snake safely is useful, although risky, but necessary for such things as visual inspections for medical reasons, determination of sex, administration of medications, measurement of length, etc. Snake restraint can also be accomplished using a squeeze box which uses a mesh lid to compress the snake into soft foam.  Again, this technique also can be risky, which is why focused safety training by experienced venomous snake handlers is important.  Techniques of snake handling are typically performed in small, controlled spaces which eliminates the potential for escape. Other safety equipment used includes face shields or handheld transparent shields for use with spitting cobras.  Again, another handling risk requiring careful safety training.  The prevention of snake bites in a zoo setting certainly is possible, but requires personnel to be inherently focused on safety training protocols along with regular snake bite response training.  Knowledge and understanding of each species’ behaviors and potential for bites is key to safe snake handling and recognizing when not handling venomous snakes is prudent.

Many of us are well aware of the methods by which birds and mammals endure the winter as endothermic or warm-blooded animals needing constant food to fuel body heat. These animals move constantly, searching for food. Alternatively, others simply go into a state of hibernation to save energy when food is unavailable. Snakes, being ectothermic animals, cannot generate their own body heat, or cool themselves through sweating, and must depend on their environment to help them adjust body temperatures according to changing needs of digestion or to escape from excessive heat or cold. So, what strategies can a cold-blooded, or ectothermic animal, like a snake employ to survive the winter cold? Snakes in temperate zones of the U.S. have no alternative but to go underground, using sites called hibernacula (singular—hibernaculum) or dens, to avoid freezing. While some mammals undergo hibernation in an inactive state to conserve energy, snakes go through a similar process called brumation, but differs in that, in some cases, movements of snakes in underground dens may still occur, as they take advantage of warmer sections within the den that shift during the winter. Indeed, some prairie rattlesnakes in more northerly temperate latitudes have been known to bask outside the entrance to their underground lair at times during warm spells in the winter!

How do snakes prepare for brumation? As the day length shortens and night time temperatures drop lower, snakes sense that cold weather is approaching and begin to move towards locations that they know from experience can provide them with a way to get underground below the freezing depth. During October, snakes stop feeding in order to clear the stomach of any food, which may typically take several days. Because snakes depend on the environment to heat their bodies to the proper digestion temperature, food must be processed out before the snake becomes too cool or it will simply rot in the stomach, often leading to fatal infections. The drive to seek out den sites becomes stronger with approaching cold weather, because cold snakes lose the ability to operate muscles that control movement and are in a race against time and freezing temperatures.

Some snake species move considerable distances, perhaps up to a few miles, in a migratory push to arrive at a den in time. These den sites range from ant mounds, crayfish and earthworm burrows and rodent burrows, to spaces within subterranean rock strata, tree stumps, crawl spaces, old wells, and basements, to highlight a few examples. Natural dens in the landscape are selected based on characteristics that favor maintaining den temperatures at optimum levels, like south-facing cliffs or mountain slopes where the sun heats the soil longer during the winter. The same dens may be used every year or new ones are selected, and snakes of multiple species may use the same den, because this site could be the only spot within many acres that enables these animals to successfully avoid freezing. Thus, rattlesnakes, bullsnakes, and garter snakes, among others, will use the same communal den. Even snake-eating snakes may be present, because cold temperatures eliminate the desire for feeding. The numbers of snakes using dens may be as few as 3-6 or as many as thousands, as found in Red-sided garter snake dens in Canada. Den sites also provide snakes with some security from predation, when being cold prevents defensive action, although badgers and skunks have been known to dig them out. Additionally, snakes also depend on these dens to prevent dehydration, a common cause of overwintering mortality in juveniles. Baby and juvenile snakes have a particularly difficult challenge in detecting overwintering den sites, because they don’t yet have knowledge of where they are found. These young snakes may attempt to follow the scent trails of adults to den sites or, failing that, hope that they locate some underground passage that goes below the frost line and allows them another chance in the coming year. The amount of time spent in brumation is solely dependent upon how soon the next warming cycle begins in the spring and can last 3-9 months. In less than perfect underground microclimate conditions, this time in brumation sometimes results in many snakes, especially juveniles, succumbing to skin fungus or dehydration.

With the warming temperatures of early spring, underground den temperatures also begin to rise, followed by snakes gradually edging closer to the den entrance. In most species of garter snakes, emergence from brumation is essentially explosive with intense reproductive copulation taking place almost immediately. Other snakes require more time to warm up the body physiologically before moving away from the dens to feed and pursue other normal behaviors. Brumation is important in that it serves to protect snakes from winter freezing and is also necessary to reset snake reproductive cycles for the coming year. In short, dens are imperative for the conservation of virtually all snake species that brumate.

Natural communal dens frequently confuse people into thinking that different snake species within are interbreeding or being eaten by other snakes. Neither of these thoughts have a factual basis. Various myths are associated with snake behaviors regarding movements towards and away from dens, as well as during brumation. Some people believe that emergence in the spring follows the first thunderstorm in which lightning strikes produce ground vibration to stir those restless serpentine souls! The Eastern or Black ratsnake, is called by some the Pilot snake, because it apparently guides rattlesnakes to dens and sometimes breeds with them there! In truth, both species are simply entering a communal den to overwinter.

Let’s begin by laying down some facts that we can sink our teeth into! There are very few species of snakes in Colorado that are considered dangerously venomous, which means that chances are that the snake you encounter next will be non-venomous, i.e., harmless to humans. Of the 30 or so species of snakes in Colorado, the good news is that only three are dangerously venomous! These three venomous snakes happen to be all rattlesnakes, but there tends to be a substantial amount of confusion in distinguishing rattlesnakes from other non-venomous snakes, despite all the information available. For example, the snake most commonly confused with rattlesnakes is the bullsnake, and this confusion transcends generations with repeated inaccurate information. Whether a newly hatched baby, juvenile, or adult, the myths associated with bullsnakes vs. rattlesnakes are clearly entrenched.

Let’s examine just a few commonly repeated myths for clarification. The first one states, “If the tail is rattling, it’s a rattlesnake”! Typically, all snakes vibrate or rattle their tail for different reasons. Usually, it happens when the snake is feeling threatened and wishes to either scare the offending threat away or, if an attack ensues, hopefully the tail will attract the brunt of the attack, and leave the head unscathed. In this way, the snake is more likely to escape with its life. If the tail vibration occurs in dry leaves or against an object that reverberates, the sound is amplified and may, in fact, mimic the rattle vibration of a rattlesnake. Watching the tail vibrate, you may notice that it is held close to horizontal in non-venomous snakes, while rattlesnakes tend to hold their tail vertically. It’s important to note that with rattlesnakes, the tail tip is usually composed of a series of segments or rattles that move when the tail tip is vibrated, creating that well known rattlesnake sound! Baby rattlesnakes only have one segment on their tail tip at first, so no sound is emitted, but the tail is still usually held vertically. In addition, rattlesnake tails are short and blunt, ending with rattle segments, while the tail in non-venomous snakes is long, with a gradual taper to only a sharp point.

The second popular myth states, “Bullsnakes can breed with rattlesnakes, creating venomous bullsnakes”. When we look at the biology of this situation, we realize this event could not possibly happen, because bullsnakes are egg layers, and rattlesnakes give birth to living young, like mammals. It just doesn’t work!

The third popular myth relates to a concept that states, “Bullsnakes chase away rattlesnakes”. Again, in looking at how these two snake species live out their lives in the same habitat, one can see that they go about life’s needs in entirely different ways, which reduces conflict and competition, allowing both snakes to co-exist. This concept may have had its origins in observing when both species occur together. Both are seen in the spring, but as the summer progresses rattlesnakes become more nocturnal, while bullsnakes may still be active when it’s not too hot. Separation of activity times may leave us with the impression that bullsnakes have indeed “chased” the rattlesnakes away!

There are several other myths, but the myths described are the most often quoted. It may useful to note that bullsnakes are not typically snake eaters, so they would not have any influence on rattlesnake populations. So, just how does someone identify a bullsnake (or other non-venomous snake) from a rattlesnake? Because many snake species have a pattern of somewhat rounded or square-shaped, dark designs on their backs, including rattlesnakes and bullsnakes, this patterning is not a reliable identification tool. Instead, look at the tail and head. We have already discussed the tail differences, so let’s focus on the head. Bullsnake head shapes are barely triangular unless the snake is hissing at you (you’re too close!), while the neck width is nearly the same as the base of the head width. Much like looking at your thumb! Rattlesnakes have a strongly triangular head with a much thinner neck width relative to the base of the head. Moreover, each side of the rattlesnake’s face we find a pair of horizontal white stripes, akin to war paint! In addition, rattlesnakes tend to adopt a tight coiled posture at rest, different from other snakes.

With the tail and head shape in your focus, you should be able to make a pretty reliable identification of whether the snake is a rattlesnake or not. As always, stay at least 3 feet away from the snake until you’re sure about your identification, still giving the snake some space, regardless.

The autumnal equinox, or the first day of fall, is today!  It’s a time when birds have already begun their gradual migrations to southerly, warmer lands, and our black bear is undergoing hyperphagia, a process of eating as much as possible to build fat reserves for winter survival. One has to wonder if the fall season affects other organisms, such as rattlesnakes, in any similar way. 

We know that in August, some rattlesnakes begin producing babies and also breeding in order to set up baby production for the next August.  With this process overlapping into September, those snakes not involved with reproduction, like females that have already given birth and other non-breeding females, and males not breeding this year, will begin to step up their fall season food search in order to increase fat stores in advance of winter. The fall season feeding binge is also necessary to ensure future baby production, occurring every year and a half to two years. This feeding process helps all rattlesnakes get through winter hibernation underground by maintaining body health, and while the focus on feeding goes on, rattlesnakes are also gradually moving to denning locations in which hibernation takes place, locations sometimes used every winter. They must be in place to hibernate by early November to avoid freezing. 

Fall is a busy time for all snake species, even those which produce babies in the spring ahead of the rattlesnake’s schedule. The earlier breeding and reproduction still means that the fall season drives snakes to feed well and gradually begin to orient their movements to areas where hibernation takes place, just like the rattlesnakes do.

Since snakes are active during the fall season, be sure to check out our snake safety tips guide. 

Written by Bryon Shipley

Prairie Rattlesnake, Adaptation

​It’s winter and this finds us writing about amphibians and reptiles rather than surveying them in the field. 
(Well, that’s not totally true as it’s not winter in the Peruvian Amazon (near Iquitos) where our Venomous Safety Instructor, Matt Cage, is guiding amphibian and reptile enthusiasts and photographers through the jungle.)
Here’s a special find he recently shared: 

​Be snake-aware on trails as you practice social-distancing methods this season.
Safety Tip: Look carefully before temporarily stepping off onto the side of a trail to make room for social distancing. Remember, snakes may be very difficult to see in the grasses near the trail.

Although rattlesnakes often give you notice of their presence by rattling, you cannot count on this all the time.Their first defense is to not be seen by you (a potential predator), and sometimes a rattlesnake is simply sleeping or soaking up the sun - the point is, they don't always rattle. Please remember that our harmless snakes also wiggle their tail, which may be perceived as rattling. Usually when they do this, their tail is against the ground to help produce noise by hitting against something. Rattlesnakes almost always hold their tail up when rattling and even while they're moving. However, if the tail is wet or the rattle is broken, they may be unable to make a sufficient warning sound. Bullsnakes, a big and harmless species, may wiggle their tail and can also provide a loud hiss which may even sound like a rattlesnake rattling.

Don't be fooled, use multiple characteristics to decide if it's dangerous or harmless, and always give plenty of space. NEVER attempt to handle any snake, and especially a rattlesnake. (Even dead rattlesnakes can deliver a horribly dangerous bite!)

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!

Download our rattlesnake safety guide! 

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.

​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. 

Bullsnake (below)

Yellow-bellied racer (above)
Wandering Gartersnake (below)

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. 

1. Rocky Mountain Arsenal Wildlife Refuge: This refuge is home to more than 330 animal species including bison, mule, and white-tailed deer. Even bald eagles winter here! You can take an 11 mile drive through the park and drive right next to the bison area. You can also take a number of short hikes, including many woodland and wetland trails, as well as our favorite - a grassland trail called Rattlesnake hill! 
2. Mount Evans Scenic Byway: Bring a lunch and take a drive up this iconic 14,264 foot mountain! It is a 28 mile drive and you can take many stops along the way to view bighorn sheep, pikas, marmots, and mountain goats. Fun fact - this is the highest paved road in North America, so bring a jacket as the temperature gradually drops while you climb up. Some stops we recommend are Echo Lake, the Denver Botanic Gardens Mount Goliath location, and the multiple lookout pull offs. 
3.  Estes Park: At this nationally recognized location, elk can be seen any time, bighorn sheep are seen at Sheep Lake in the summer, and moose frequent willow thickets along the Colorado River.  Overall, there are hundreds of wildlife species to be seen. They will customize your trip for you and make this an experience your kids will never forget. 
4. Guanella Pass:  Look for mountains goats, bobcats, beavers, bighorn sheep, and various bird species as you drive this beautiful 23 mile stretch of road. You will journey between two watersheds - South Platte and Clear Creek, through spruce and aspen groves until you hit the treeline - where the trees stop growing and the tundra begins. There are a number of trails you can hike along and get some incredible photos of the scenery and wildlife! We recommend the famous Guanella Pass Trail - it is easily accessible and not super strenuous. 
5. Wild Animal Sanctuary: This sanctuary is known for rescuing wildlife, especially of predatory nature, and rehabilitating them. There’s a 1.5 mile elevated walkway you can take to view tigers, bears, lions, and more. The animals roam free, so every time you come, there’s a chance to see something/someone different. Since the summers can be hot, come at sunrise or take advantage of the Sanctuary’s Wild Nights program. 

Remember! Anywhere you go:

• Keep a safe distance from wildlife.
• Use binoculars and zoom lenses if you want to observe wildlife closer.
• Never stop or block traffic.
• Never follow or chase animals.
• Observe quietly - there’s a lot to see and hear! 
• Keep all pets on leash.
• Leave each place you stop and visit as you found it! 
• Have fun, be safe, and enjoy nature!