Crotalus cerastes Sidewinder
Some other names for this species:
Horned Rattlesnake
Subspecies I've seen:
C. c. cerastes
Mohave Desert Sidewinder
C. c. cercobombus
Sonoran Sidewinder
C. c. laterorepens
Colorado Desert Sidewinder
Crotalus cerastes cerastes Mohave Desert Sidewinder
Pinto Basin, Joshua Tree National Park, Riverside County, CaliforniaMay 19, 2001
Mohave Desert Sidewinder (Crotalus cerastes cerastes)
Sidewinders are mostly nocturnal, so we were lucky to encounter this feisty little guy at about 9:30 AM. My friend Don MacCubbin was looking for a slightly shady spot amongst the creosote bushes to change the film in his camera. When he found the nearest shady spot, he discovered at the last moment that this sidewinder had found it first.

Sidewinders are most notable among rattlesnakes for the "horns" above their eyes and their peculiar sideways slithering. They're among the smallest rattlesnakes, but they still pack a mean wallop, as the cowboys probably had occasion to say. Bartlett & Tennant observe:

Despite the small size of this snake, relatively long fangs, a rather virulent venom, and a readiness to bite if molested, dictate that bites by this rattlesnake should be avoided. Since the venom yield is rather small, envenomation is probably not life-threatening. Envenomation will, however, be sufficiently painful to induce you to use greater future care.

We saw this snake very near the border between the ranges of the Mojave Desert Sidewinder and the Colorado Desert Sidewinder, two subspecies of the same species. The most reliable way to tell them apart is to count the scales around the middle of the body. This would require holding the snake still. Keeping in mind the observation quoted above, I chose to identify this snake an alternate way.

I initially identified it as a Mojave Desert Sidewinder, because the end of the tail right before the rattle is black in Colorado Desert Sidewinders and brown in Mojave Desert Sidewinders, and from my photos, this one's tail end appeared black. My friend Fred Harer pointed out that in Colorado Desert Sidewinders he's seen further south, the black end of the tail is considerably more obvious than in this picture. He later contacted a university herpetologist who concurred that this appeared to be a Mojave Desert Sidewinder, so I've changed the identification of this one.

Stovepipe Wells, Death Valley National Park, Inyo County, CaliforniaApril 2, 2005
Mohave Desert Sidewinder (Crotalus cerastes cerastes)
This tiny little baby sidewinder was coiled up in the meager shade of a creosote bush when I noticed its pattern in the early morning. At first glance I thought it was a discarded bracelet.
Red Rock Canyon State Park, Kern County, CaliforniaSeptember 7, 2006
Mohave Desert Sidewinder (Crotalus cerastes cerastes)
This tiny little guy was creeping along the road just outside of the Red Rock Canyon campground. The road at that point had steep curbs about six inches high, which was clearly higher than the snake would be able to navigate. I let it climb onto a stick and transferred it to the nearby desert. It was moving very slowly, possibly because it was quite a chubby little snakeling.
near Pearsonville, Inyo County, CaliforniaSeptember 8, 2006
Mohave Desert Sidewinder (Crotalus cerastes cerastes) Mohave Desert Sidewinder (Crotalus cerastes cerastes)
The next night, my friend Fred Harer, his wife, his mom, and I did some night cruising for herps from Kennedy Meadows down to Pearsonville along Nine Mile Canyon Road. For quite a while it seemed that all we would see were toads, but as we descended into the warm desert night Fred spotted two little baby sidewinders on the road, both of which he ushered off the road.
Red Rock Canyon State Park, Kern County, CaliforniaSeptember 10, 2007
Mohave Desert Sidewinder (Crotalus cerastes cerastes) Mohave Desert Sidewinder (Crotalus cerastes cerastes)
Driving back to the Monterey coast from Las Vegas (via Death Valley and Whitney Portal), we camped for a night at one of our favorite spots in the Mojave desert: Red Rock Canyon State Park. After dark I took my flashlight and walked along the road leading to the campground looking for snakes or other wildlife activity. I had nearly finished my walk with nothing to show for it when I came across this handsome little sidewinder in the campground area.
Crotalus cerastes cercobombus Sonoran Sidewinder
Pima County, ArizonaAugust 2, 2009
Sonoran Sidewinder (Crotalus cerastes cercobombus)
After an evening of radio-tracking rattlers with Roger Repp and some of his friends who were visiting from Chicago, we were heading back for a long-awaited good night's sleep. But on the way, we took a detour to look for sidewinders. Roger practically guaranteed us a sidewinder. First we took an unfortunately uneventful drive down a long, wide, flat dirt road. Next we took an unfortunately exciting rental-car-scraping drive down a long, narrow, bumpy dirt road. Fortunately for me, I was with Roger in his Indestructible Herpmobile, so only the Chicagoans had to worry about the rental-car-scraping aspect of the journey. Unfortunately for everyone, there were still no sidewinders to be seen. So we got back on the paved road and headed homeward once more. Several miles down the road the Chicagoans noted an unusual shape, which turned out to be this oh-so-gravid snake.
Crotalus cerastes laterorepens Colorado Desert Sidewinder
Anza-Borrego Desert State Park, San Diego County, CaliforniaJuly 2, 2006
Colorado Desert Sidewinder (Crotalus cerastes laterorepens)
This was the first of two sidewinders I came across within half an hour of dusk. This one was out prowling about ten feet away when it saw me. It started rattling while retreating to the protection of a bush, where I got this photo.

I've got to agree with Fred that the black tip of the tail here is much more prominent than on the first sidewinder that I photographed five years earlier.

Borrego Springs, San Diego County, CaliforniaApril 22, 2009
Colorado Desert Sidewinder (Crotalus cerastes laterorepens)
On this spring trip to Anza-Borrego Desert State Park and environs, sidewinders were the second most common snakes on the road. Where the most common, Western Shovel-nosed Snakes, were smooth, colorful, and fast-moving, the sidewinders were rough-scaled, beige, and typically motionless. They would typically flatten out on the road, presumably for the warmth. This one was the largest and flattest.
Anza-Borrego Desert State Park, San Diego County, CaliforniaApril 30, 2009
Colorado Desert Sidewinder (Crotalus cerastes laterorepens)
Some of the sidewinders I saw on the roads at night were amazingly good matches for the appearance of the pavement. Here's a youngster that was very hard to rediscover once I had turned my flashlight away from it momentarily.
Borrego Springs, San Diego County, CaliforniaJune 19, 2012
Colorado Desert Sidewinder (Crotalus cerastes laterorepens)
Against a dark road, a flat heat-absorbing sidewinder is very easy to see.
Borrego Springs, San Diego County, CaliforniaJune 21, 2012
Colorado Desert Sidewinder (Crotalus cerastes laterorepens)
But against a lighter road, a flat heat-absorbing sidewinder can blend in remarkably well.
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