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Western Patch-nosed Snake (Salvadora hexalepis)

[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”2130″ img_size=”large” alignment=”center” style=”vc_box_rounded”][vc_column_text]Western Patch-nosed Snake, Salvadora hexalepis hexalepis, Yuma Desert, AZ. Photo by Jim Rorabaugh.[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2516″ img_size=”medium” alignment=”center” onclick=”img_link_large”][vc_column_text]Salvadora hexalepis deserticola. 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=”2517″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Western Patch-nosed Snake (S.h. deserticola), Santa Cruz Co., 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=”2519″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Western Patch-nosed Snake (S.h. hexalepis). ©2013 Dancing Snake Nature Photography[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2518″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Western Patch-nosed Snake (Salvadora hexalepis hexalepis). Photo by Young Cage[/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=”2520″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Western Patch-nosed Snake (Salvadora hexalepis hexalepis). Photo by Young Cage[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/2″][vc_single_image image=”2521″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Western Patch-nosed Snake (Salvadora hexalepis hexalepis). 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 Western Patch-nosed Snake is a racer-like species of moderate size (< 1168 mm total length).  It is slender with a dark dorsolateral stripe and a thinner, dark lateral stripe on each side. This species has a large, triangular free-edged rostral scale, and the anterior edge of the posterior chinshields are usually separated by 2-3 small scales. The dorsal scales are mostly smooth (adult males may have keeled scales above the vent) and in 15-17 rows at mid-body. The anal plate is divided.  Two fairly distinct and disjunct forms occur in the 100-Mile Circle, which are sometimes considered separate species (see Ernst and Ernst 2003, and Degenhardt et al. 1996):

Big-Bend Patch-nosed Snake (Salvadora hexalepis deserticola): The mid-dorsal area between the dark dorsolateral stripes is tan or orange-brown as compared to the lighter and drab background color on the sides of the snake. The dark, thin lateral stripe is often fused with the broader dorsolateral dark stripe near the head, but is separate and located on the 4th scale row just posterior to the neck.  The dark stripes are distinct and have clean edges.  Usually one, but sometimes two loreals are present on each side, and two of the nine supralabials contact the eye. This form is found in southeastern Arizona and adjacent portions of Sonora in valleys, bajadas, and lower montane slopes under about 1560 m.  It occurs in higher, eastern examples of Sonoran desertscrub, semi-desert and Plains grassland, Chihuahuan desertscrub, and lower oak woodlands and savanna.

Western Patch-nosed Snake (Salvadora hexalepis hexalepis): The mid-dorsal area between the dark dorsolateral stripes is about the same drab shade as the background color lower on the sides. A lateral dark stripe is fused with the dorsolateral dark stripe just behind the head, and then is located on the 3rd and 4th scale rows posterior to that.  The dark stripes have jagged edges. From two to four loreals are present on each side, and usually none or one of the nine supralabials contact the eye. In the Circle, this form occurs mostly in Sonoran desertscrub, generally to the west and north of Tucson.

The only snake in our area with which the Western Patch-nosed Snake is likely to be confused is the Eastern Patch-nosed Snake. It resembles the Big-Bend Patch-nosed Snake but has only one or no scales separating the anterior edge of the posterior chinshields, and the lateral dark stripe is either absent or located on the 3rd scale row. The Eastern Patch-nosed Snake generally occurs at higher elevations into the mountains of southeastern Arizona, but the Eastern and Western species can occur together on the upper bajadas or lower montane slopes.  Gartersnakes are striped and of similar size to Salvadora, but they lack the enlarged rostral scale and have keeled dorsal scales.

Western Patch-nosed Snakes are terrestrial and diurnal; in the Circle, they have been found every month of the year except January.  This species is often found basking or active later and earlier in the year than other snakes.  It likely mates in the spring, and 3-10 eggs are laid in June or July. Females may not reproduce every year.  Hatchlings resemble adults but are 210-280 mm total length. This active forager crawls about searching for prey that includes mostly lizards, but also small snakes, reptile eggs, small rodents, and grasshoppers.  It uses its enlarged rostral scale to unearth reptile eggs and other buried prey.  In Sabino Canyon, a captured Long-nosed Leopard Lizard regurgitated a Western Patch-nosed Snake.

The Western Patch-nosed Snake is listed as a species of least concern on the IUCN’s Red List.  With a valid Arizona hunting license, up to four can be collected per year or possessed. There is no evidence or reason to believe it has declined in our area or throughout its range, except in urban and agricultural areas.

Suggested Reading:

Brennan, T.C., and A.T. Holycross. 2006. Amphibians and Reptiles in Arizona. Arizona Game and Fish Department, Phoenix, AZ.

Degenhardt, W.G., C.W. Painter, and A.H. Price. 1996.  Amphibians and Reptiles of New Mexico. University of New Mexico Press, Albuquerque.

Ernst, C.H., and E.M. Ernst. 2003. Snakes of the United States and Canada. Smithsonian Books, Washington, D.C.

Goldberg, S.R. 1995. Reproduction in the western patch-nosed snake, Salvadora hexalepis, and the mountain patch-nosed snake, Salvadora grahamaie (Colubridae), from Arizona. The Southwestern Naturalist 40(1):119-120.

Lazaroff, D.W., P.C. Rosen, and C.H. Lowe. 2006. Amphibians, Reptiles, and Their Habitats at Sabino Canyon. University of Arizona Press, Tucson.

Author: Jim Rorabaugh

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