The Natural World

By Tina Mitchell

Spring brings longer, warmer evenings that lure me outside after dinner. Once with our dogs on a postprandial stroll, I noticed the rustling of dried oak leaves. Do oaks grow in this area? Nope, no oaks anywhere near. Instead, a Prairie Rattlesnake sat coiled at the switchback we had all just walked by, signaling us with its eponymous rattles. Why it sent this warning after the dogs and I had passed remains a mystery to me. But I keep that memory with me as reminder call to be a tad more vigilant as the weather warms.

As exothermic (cold-blooded) creatures, snakes rely on heat from the sun and the ground to regulate their body temperatures. During the winter, they hibernate – sometimes gathering in large numbers – in rodent dens or rock crevices. But as daytime temperatures climb to 50 degrees and above, the likelihood of encountering a snake rises too.

In Central Colorado, only one species of snake presents any serious danger – the venomous Prairie or Western Rattlesnake. Rattlers can shake their rattles up to 100 times per second – faster even than a hummingbird can beat its wings. A mature rattler can control the amount of venom it delivers with any strike – less for small prey, more for a defensive strike. (That’d include us humans.) Its forked tongue, continually moving up and down, samples the air for airborne and ground-hugging scents.

Although Colorado has 28 species of snakes, only three other species provide the likely encounters in our area. Probably the most commonly seen snake, the Gopher (or Bull) Snake lives in many habitats and tolerates human activity well. When checking nest boxes once, I spotted an odd-looking insect along the opening at the top of the box’s door. I mostly worry about surprising paper wasps there; other insects rarely create problems. So I opened the door. There I stood, staring at the belly of a small Gopher Snake. Quickly closing the door, I stepped back and realized that what had looked like an insect at the opening was actually the eyes and nostrils of the snake, peering out of the box. It kept watching even after I closed the box. (Tolerant of humans, indeed.) Gopher Snakes can be mistaken for rattlesnakes, especially since one may coil and raise its head defensively if threatened. It can even shake its tail against dry vegetation, sounding very much like a rattlesnake. These similarities probably result in the indiscriminate killing of these harmless snakes. In fact, they eat many rodents, providing important pest control.

The Coachwhip’s tail sports a pattern resembling a braided whip such as those used by coach drivers. A few years ago, my husband snapped a photo of a reddish snake with dark barring – a Coachwhip! As one of the fastest snakes in North America, it can move faster than some humans. Although not venomous, it can be fairly aggressive if cornered, striking repeatedly at any threat. And finally, the familiar Terrestrial Garter Snake lives in almost any habitat – even as high as 11,000 feet, making it Colorado’s highest-living reptile.

If you can overcome an archetypal fear reaction, you might appreciate that snakes are fascinating creatures. They can move forward quickly via contractions of their muscular bodies – but they can’t move backward. Many can climb trees with ease. Venomous snakes have vertical elliptical pupils; non-venomous snakes, round pupils. (But I don’t recommend getting close enough to make that distinction.) The skull has many joints and the lower jaw connects at the front by a flexible ligament, allowing expansion to swallow surprisingly large prey. Most snakes are oviparous, laying a clutch of leathery eggs in late summer. However, a few ovoviviparous species (e.g., rattlesnakes) retain fertilized eggs inside their bodies, where the young mature within individual membranes encompassing yolk sacks for nutrients. Garter snake young actually connect to the female via rudimentary placentas, making them viviparous, as are mammals. Once mature, both rattlesnake and garter snake young leave the mother’s body as a live birth.

Many people desperately fear our lone venomous species, although deaths from their bites are rare among healthy adults. (You still should seek medical attention for any snake bite, since their mouths can carry a whole host of infectious agents.) Generations of Boy Scout training and heroes in Westerns taught us to suck poison out of a venomous bite. Later, a suction device took the place of a mouth. But most experts today agree that the best snake bite kit is a set of car keys. Stay calm (good luck with that!), keep the site below the level of the heart, and drive like crazy to the nearest medical help.

And let’s be careful out there.


Tina Mitchell watches nature with her human and canine family from their perch in the piñon/juniper habitat of western Fremont County. When she needs to pay the bills, she shows up as a research psychologist on the University of Colorado Anschutz Medical Campus in Aurora.