Sidewinder – Tucson Herpetological Society

[vc_row][vc_column][vc_column_text]

Sidewinder (Crotalus cerastes)

[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”2154″ img_size=”large” alignment=”center” style=”vc_box_rounded”][/vc_column][vc_column width=”1/2″][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2727″ img_size=”medium” alignment=”center” onclick=”img_link_large”][vc_column_text]Impression in sand left by a cratered Sidewinder, Yuma County, AZ. Photo by Jim Rorabaugh[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2730″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sidewinder tracks, Yuma County, AZ. Photo by Jim Rorabaugh[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2728″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sidewinder, Photo by Jerry Schudda[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2729″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sidewinder preying on a Desert Iguana, Algodones Dunes, SE CA. Photo by Jim Rorabaugh[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2731″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sidewinder eating Kangaroo Rat. In-situ, northeastern Baja California. Photo by Warren Savary[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2732″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Cratered Sidewinder. Photo by Jim Rorabaugh[/vc_column_text][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2733″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sidewinder, Kofa National Wildlife Refuge, AZ. Photo by Jim Rorabaugh[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2734″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sidewinder, Photo by Young Cage[/vc_column_text][/vc_column_inner][/vc_row_inner][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2736″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sidewinder, Photo by Young Cage[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2735″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Sidewinder, Photo by Young Cage[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column width=”1/6″][/vc_column][vc_column width=”2/3″][vc_column_text]

Description

The Sidewinder (Crotalus cerastes), with its characteristic horns over the eyes (enlarged and pointed supraocular scales) and the sidewinding locomotion for which it was named, is perhaps our most distinctive rattlesnake. This is a relatively small rattlesnake (< 824 mm total length) and heavy-bodied. The dorsal pattern is a row of mid-dorsal dark blotches and three rows of smaller dark spots or blotches on each side on a light cream, tan, or light gray background. There are 2-7 dark bands on the tail. The dark blotches, spots, and tail banding are often faded and obscure in the Colorado Desert Sidewinder (C. c. laterorepens). A dark bar runs from the eye backwards and down. The basal segment of the rattle is black. The keeled dorsal scales are usually in 19-25 rows at mid-body and along the mid-dorsum is a spiny, heavily-keeled ridge. Like all pit vipers, it has a heat-sensing pit between the eye and nostril. The pupil is vertically elliptical and the anal plate is undivided. The purpose of the horns over the eyes is not clear. However, they may help protect the eyes as the snake moves through burrows or could act as shades against the intense desert sun. Although unique in our area, other vipers in Latin America and elsewhere in the world have similar structures. The Horned Viper (Cerastes cerastes) closely resembles the Sidewinder and is an ecological equivalent to it in the deserts of North Africa and the Middle East. It even sidewinds.

In the 100-Mile Circle, the Sidewinder is almost exclusively a species of the Sonoran Desert. It is most widely distributed and common in the Lower Colorado River Subdivision of that desertscrub; however, it enters the Arizona Upland Subdivision in the eastern portions of its range, such as on the western bajada of the Tucson Mountains and in the Waterman Mountains. In the Circle, this snake occurs primarily in valleys and bajadas; however, it occasionally penetrates into desert mountains along broad, sandy arroyos. It is often abundant where substrates are sandy, but is by no means limited to those areas. Sidewinder records in the 100-Mile Circle are mostly below 795 m. The exception is a collection from 1220 m on the southwestern slope of the Pinal Mountains in Gila County (UAZ 27506; identity of the specimen confirmed by the author). The locality appears to be in semi-desert grassland; however, Sonoran desertscrub is nearby to the south in the Gila River Valley.

In the Circle, Sidewinders are distributed primarily to the west and north of Tucson, from the Tucson Mountains westward to Organ Pipe Cactus National Monument, and northward to Coolidge, Florence, and the deserts around Phoenix. The Pinal Mountains specimen, which is the only Gila County record, suggests the species follows the Gila River Valley perhaps to Kearny, Winkelman or beyond. Elsewhere, the Sidewinder occurs throughout much of western Arizona, southeastern California, southern Nevada, and southern Utah. In Mexico it occurs in the northeastern portion of the Baja California Peninsula and western Sonora to near Hermosillo. It also occurs on Isla Tiburón, Sonora.

In Arizona, the Sidewinder achieves its greatest densities in the sandy, southwestern desert valleys. As an example, Fowlie (1965) found 47 Sidewinders on a moonlit night on old US 80 between Yuma and Gila Bend. In sandy deserts, its sidewinding tracks are often seen at night or in the morning before the wind scrubs them away. This form of locomotion results in a series of “J” shaped slashes across the sand. The hook portion of the “J” is made by the head, the T portion is made by the tail. The direction of the hook on the “J” points in the direction the snake is traveling. So, in the image gallery, the snake that made those sidewinding tracks was moving from the lower left to the upper right in the picture. The snake loops portions of its body forward from one track to the next, always touching at least two of the “J” shaped marks. Although they are adept at sidewinding, they also employ undulatory and rectilinear locomotion to move forward, as other snakes do. Sidewinders are also known for “cratering.” While coiled, the snake shuffles into the sand, and then may use its head and neck to pull sand atop its coils. Partially hidden, a cratered Sidewinder is well poised to ambush lizards or rodents that happen by. Although primarily nocturnal, Sidewinders are often found cratered into the sand in the morning. As surface temperatures approach 35⁰C the snakes move into rodent burrows or under other cover. Sidewinders in the 100-Mile Circle have been collected from early March to late October. I have seen the distinctive tracks of this species just outside of the Circle in Sonora in mid February.

Sidewinders mate in the spring, possibly again in the fall, and bear litters of 1-20 live young (mean = 9.2) from mid-August into late November. Neonates resemble small adults, but are 155-205 mm total length at birth and have yellow at the base of the rattles. Prey is obtained primarily by ambush. Coiled neonates wave their yellowish tails to lure in lizards. The adult Sidewinder feeds mostly on small rodents and lizards, while juveniles consume mostly lizards. Birds, small snakes, and Antelope Ground Squirrels have also been reported in the diet. In Yuma County, small mammals, lizards, birds, and snakes made up 51.5, 42.7, 2.9 and 2.9% of the diet by frequency, respectively (Funk 1965). A caterpillar was found in the stomach of one Sidewinder, but it may have been secondarily ingested (in the stomach of a lizard, or swallowed while eating a lizard). Sidewinders will eat carrion, as well, and are not averse to scavenging road kill rodents.

Sidewinders have relatively long fangs (5.0-8.1 mm). Compared to other rattlesnakes, the venom is moderately toxic and the venom yield is low. Bite victims usually experience relatively mild symptoms that include pain, swelling, itching, discoloration, weakness, dizziness, and necrosis at the site of the bite; however, fatalities have occurred. This small snake can be surprisingly aggressive, and a particularly peeved Sidewinder may pursue a human that harasses it.

Four Sidewinders can be captured per year or held in possession with a valid Arizona hunting license, although take is prohibited without special authorization in protected areas such as Organ Pipe Cactus National Monument and Cabeza Prieta National Wildlife Refuge. The Sidewinder is listed as a species of least concern on the IUCN’s 2015 Red List. Sidewinders are eliminated by agriculture and urban development, but there is no reason to believe they are declining in wild lands. The subspecies Crotalus cerastes cercobombus predominates in our area, although C. c. laterorepens may occur on the southwestern boundary of the 100-Mile Circle. Three subspecies have traditionally been recognized; however, genetic studies revealed five clades. Deep divergence between Mexican and Arizona populations of C. c. cercobombus indicate that morphological and pattern differences or similarities in this species do not necessarily equate to evolutionary units (Douglas et al. 2006).

Sidewinder (Crotalus cerastes)

Description

DONATE TODAY

THANK YOU FOR YOUR SUPPORT

Search the Site

CONTACT THS

Archive