A Colorado Desert Sidewinder found on a road at night rattles and sidewinds.
A Colorado Desert Sidwinder sidewinding at night.
A Colorado Desert sidewinder crawls with its unique sideways locomotion.
Listen to the faint rattling of a sidewinder.
California park warning sign.
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rattlesnake warning signs.
Rattlesnakes are important members of the natural community. They will not attack, but if disturbed or cornered, they will defend themselves. Reasonable watchfulness should be sufficient to avoid snakebite. Give them distance and respect.
"Rattlesnakes are also among the most reasonable forms of dangerous wildlife: their first line of defense is to remain motionless; if you surprise them or cut off their retreat, they offer an audio warning; if you get too close, they head for cover. Venom is intended for prey so they're reluctant to bite, and 25 to 50 percent of all bites are dry - no venom is injected."Leslie Anthony. Snakebit: Confessions of a Herpetologist. Greystone Books, 2008.
Rattlesnake bites can be extremely dangerous, but rattlesnakes should not be considered as vicious and always ready to attack without provocation. They will not strike without a reason, but they will aggressively defend themselves. They are often portrayed with the body partly coiled, the tail rattling loudly, and the head up ready to strike. This display is a warning not to come any closer or they will strike; a defensive behavior that some rattlesnakes use when they sense that crawling away would put them in danger. If they are given some space and some time to escape to a safe place, they will usually crawl away as fast as possible.
Because they cannot crawl to safety as fast as some snakes, rattlesnakes often use their cryptic color and pattern to blend into their surroundings in order to hide from their prey and from other animals that could threaten them. They often hunt by sitting still and waiting for a warm-blooded prey animal to pass close enough for the snake to strike it. Sometimes a passing human will be struck instead, mistaken for food. When they sense the presence of something that might threaten them, rattlesnakes often lie still to avoid detection and do not rattle, because that would give away their location. At other times they rattle loudly, sometimes from a good distance, to warn potential enemies of their presence. In both cases they are doing everything they can to avoid confrontation and to avoid striking and biting and using up their valuable supply of venom which they need to kill and digest their food.
A bite by this snake can be very dangerous without immediate medical treatment.
Treatment can require hospitalization and great expense.
Adults are 17 - 33 inches. (43 - 84 cm). Snakes encountered will generally be 12 - 18 inches.
Juveniles are about 7 inches at birth.
A heavy-bodied venomous pit viper with a thin neck, a large triangular head, and a thick tail with a rattle, consisting of loose interlocking segments, at the end. A new rattle segment is added each time the skin is shed, which can be more than one time per year.
Pupils are elliptical. Scales are keeled.
The supraocular scale over each eye is enlarged and raised up over the eye giving the appearance of a "horn" over each eye. These scales can fold down over the eyes to protect them when the snakes is buried or crawling in underground burrows.
Heat sensing pits on the sides of the head help the snake to locate prey by their warmth.
Long, hollow, movable fangs connected to venom glands inject a toxic venom which quickly immobilize the prey. The snake can control the amount of venom injected and the fangs are replaced if broken. Though the amount of venom a sidewinder injects is relatively small and rarely deadly, bites on humans are potentially dangerous. Even a dead snake can bite and inject venom if the jaws open reflexively when they are touched.
The segment of the rattle closest to the body is black.
Color and Pattern
Pale cream, tan, brown, pink, or grayish back color usually closely matches the soil surface allowing the snake to blend in with the background.
Around 40 darker blotches on the back.
A dark stripe extends through each eye.
Juveniles are born with only a single rattle button at the end of the tail.
The segment of the rattle closest to the body on an adult Mojave Desert Sidewinder is brown,
while that of the Colorado Desert Sidewinder is black.
Life History and Behavior
Primarily nocturnal and crepuscular during periods of excessive daytime heat, but also active during daylight when the temperature is more moderate.
Not active during cooler periods in Winter.
Moves with a sidewinding locomotion, throwing raised loops of the body to the side to push itself forward in an s-sheped curve. A sidewinders trail looks like a series of parallel j-shaped lines pointing roughly 45 degrees from the direction of movement.
Sound - The Rattle
When alarmed, a rattlesnake shakes its tail back and forth. The movement rubs the rattle segments together producing a buzzing sound which serves as a warning. Newborn snakes have only one rattle segment which does not make a sound.
Diet and Feeding
Eats mainly lizards when young, and increasingly larger prey including small rodents when grown.
An ambush hunter, it sits buried beneath the surface of loose sand with just the top of the head showing, near kangaroo rat warrens, and lizard or rodent trails, then strikes at and releases the prey. The snake then follows the trail of the envenomated animal and swallows it whole.
Live-bearing. Young are born late summer to mid-autumn.
This subspecies, Crotalus cerastes laterorepens - Colorado Desert Sidewinder, is found in southeastern California - roughly south of the San Bernardino County line and west to the slopes of the peninsular ranges.
The species Crotalus cerastes - Sidewinder, is found in the Southern California deserts, east through southern Nevada to extreme southwestern Utah, into western Arizona, and south into northeast Baja California Mexico, and northwest Sonora, Mexico.
Inhabits primarily areas of wind-blown sands, especially where sand hummocks are topped withvegetation. Also found in hardpan, open flats, rocky hillsides, and other desert areas, especially those grown with creosote bush, where the terrain is open, not obstructed by rocks or vegetation, allowing the broad sidewinding locomotion.
Crotalus - Greek - krotalon - a rattle - refers to the rattle on the tail
cerastes - Greek - kerastes - horned - referring to the "horns" on head
laterorepens - Latin - later - side and repens - creeping or crawling - refers to the curious style of "sidewinder" locomotion