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Green Ratsnake (Senticolis triaspis)

[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/vc_column][/vc_row][vc_row][vc_column width=”1/2″][vc_single_image image=”2107″ img_size=”large” alignment=”center” style=”vc_box_rounded”][vc_column_text]Green Ratsnake, Pajarito Mtns, AZ. Photo by Tom Jones[/vc_column_text][/vc_column][vc_column width=”1/2″][vc_row_inner][vc_column_inner width=”1/2″][vc_single_image image=”2362″ img_size=”medium” alignment=”center” onclick=”img_link_large”][vc_column_text]Green Ratsnake, Santa Cruz 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=”2363″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Green Ratsnake, Santa Cruz 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=”2361″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Green Ratsnake, Santa Cruz 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=”2364″ img_size=”medium” alignment=”center” style=”vc_box_rounded” onclick=”img_link_large”][vc_column_text]Hatchling Green Ratsnake. Cochise Co., AZ. Photo by Bill Radke[/vc_column_text][gap size=”12px” id=”” class=”” style=””][/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 Green Ratsnake (Senticolis triaspis) is a relatively long (< 1830 mm total length, 1500 mm SVL), and slender snake with a long tail (23-37% of total length).  The head is elongated and broader than the neck, the anal plate is divided, and there are 30-39 mid-body dorsal scale rows.  Dorsal scales are mostly smooth, but may show some weak keels, particularly along the mid-dorsal line.  Adults 800 mm total length and longer are uniform gray-green, green, or yellowish-green dorsally.  Hatchlings and juveniles are tan or gray with a series of dark blotches on the body and tail that fade with age.  The venter is white to yellowish and unmarked.

Adults are unmistakable; they are the only snake in our area with a uniform dorsal pattern that is green or mostly green.  Juveniles, however, resemble and can easily be mistaken for Glossy Snakes (Arizona elegans).  Juvenile Green Ratsnakes also superficially resemble young Coachwhips (Masticophis flagellum).  However, neither of those snakes have elongated heads distinctly broader than the neck, the Glossy Snake has an undivided anal plate, and the Coachwhip has 17 scale rows at mid-body.

The Green Ratsnake is a largely tropical species at the northern edge of its distribution in southeastern Arizona and southwestern New Mexico.  In Arizona it is known from the Quinlan, Baboquivari, Pajarito, Atascosa, Santa Rita, Patagonia, Empire, Chiricahua, Dos Cabezas, Swisshelm, Pedregosa, Peloncillo, and Pinaleño mountains. It was only recently found in the Pinaleños, in Wet Canyon (Sharp 2017). The species occurs at elevations of about 960-1620 m in the Circle.  Few records exist for the Sonora portion of the 100-Mile Circle, but it is known from Rancho El Aribabi at the southeastern base of the Sierra Los Pinitos, and Rancho Esmeralda in the Sierra Cibuta complex (southwest of Nogales).  It likely occurs in most other sierras in the Mexican portion of the Circle below about 1620 m.  In our area, it is a species primarily of oak woodland and savanna, and adjacent mesquite-invaded semi-desert grassland.  An imprecise locality on Highway 86 north of the Quinlan/Coyote Mountains may have been in an area of transition between semi-desert grassland and Sonoran desertscrub.  The Rancho El Aribabi record is also from a semi-desert grassland – Sonoran desertscrub ecotone.  At Leslie Canyon the species occurs in an area of Chihuahuan desertscrub through which a narrow riparian corridor runs. Records in the 100-Mile Circle are often from rocky canyons with intermittent or permanent flow.  Range wide, the Green Ratsnake occurs from southeastern Arizona, the Peloncillo and Animas mountains of southwestern New Mexico, and Tamaulipas, Mexico south through the lowlands and adjacent foothills and lower mountains to central Costa Rica.

Seasonally, most records in Arizona range from mid-March to late November, although one Green Ratsnake was collected near Ruby on 4 December, and a telemetered snake in Cave Creek of the Chiricahua Mountains moved among sites in December and January (Sherbrooke 2006).  Telemetry of two snakes in Cave Creek (Sherbrooke 2006) and four at Leslie Canyon National Wildlife Refuge (NWR), Swisshelm Mountains (Radke and Malcom 2005, 2009) revealed that this species spends a good deal of time on rocky slopes, often under or amidst boulders.  Of 89 locations of telemetered snakes at Leslie Canyon NWR, 55% were in talus, 25% were in living vegetation, 11% were in woody debris, and 9% were in rodent burrows.  Eighty-four percent of observations were in desertscrub and the remaining 16% were in the riparian corridor. The snakes showed a preference for east-facing slopes. At Leslie Canyon, arboreal activity was only observed once.  The Green Ratsnake is, however, a capable climber and is sometimes found well off the ground in trees and shrubs.  One of the telemetered snakes in Cave Creek was found sunning itself on a branch 4 m up in an Arizona Oak.  It was also found in a rock crevice 6 m above the ground.  The Green Ratsnake is primarily diurnal; most activity occurs mornings and late afternoon, but they are not uncommonly found on roads after dark in the early evening.  When approached, they often remain motionless.

In Arizona, Green Ratsnakes mate in the spring and produce one clutch of 2-9 eggs in June or July.  Incubation periods range from 25-100 days depending on temperature, and hatchlings are 280-400 mm total length. Farther south, Green Ratsnake reproduction is aseasonal or continuous.  Females mature at about 625 SVL.  Items reported in the diet include small mammals, bats, birds and their eggs, and lizards.  Captives have reportedly consumed mice and birds.  Captives from Leslie Canyon NWR ate seven species of rodents, but refused four species of native lizards (Radke and Malcom 2005). Rorabaugh et al. (2016) witnessed an attempted predation of a juvenile Green Ratsnake by Mexican Jays in South Fork of Cave Creek, Chiricahua Mountains.

The IUCN has yet to evaluate the conservation status of the Green Ratsnake.  With a valid Arizona hunting license, two can be taken per year and four held in possession, alive or dead, except that take is prohibited without specific authorization in protected areas such as Leslie Canyon and Buenos Aires NWRs.

Suggested Reading:

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

Cranston, T. 1989. Natural history and captive husbandry of the western green rat snake. Vivarium 2:8-11, 23.

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

Goldberg, S.R. 2003. Senticolis triaspis (Green Ratsnake). Reproduction. Herpetological Reviw 34(1):72-73.

Radke, W.R., and J.W. Malcom. 2005. Ecology and natural history of the Green Rat Snake at Leslie Canyon National Wildlife Refuge, Cochise County, Arizona. Pages 434-437 in G.J. Gottfried, B.S. Gebow, L.G. Eskew, and C.B. Edminster (compilers), Connecting mountain islands and desert seas: biodiversity and management of the Madrean Archipelago II. Proceedings RMRS-P-36, Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station.

Radke, W.R., and J.W. Malcom. 2009. Notes on the ecology of Green Ratsnakes (Senticolis triaspis) in southeastern Arizona. Herpetological Conservation and Biology 4(1):9-13.

Rorabaugh, J.C., T.J. Tibbitts, S.J. Sferra, and M.J. Sredl. 2016. Attempted predation on a Green Ratsnake (Senticolis triaspis) by Mexican Jays (Aphelocoma wollweberi). Sonoran Herpetologist 29(4):56-57.

Rorabaugh, J.C., and J.A. Lemos Espinal. 2016. A Field Guide to the Amphibians and Reptiles of Sonora, Mexico. ECO Herpetological Publishing and Distribution, Rodeo, New Mexico, USA.

Savage, J.M. 2002. The Amphibians and Reptiles of Costa Rica. University of Chicago Press, Chicago and London.

Sharp, J.C. 2017. Senticolis triaspis (Green Ratsnake). Geographic Distribution. Herpetological Review 48(2):392-393.

Sherbrooke, W.C. 2006. Habitat use and activity patterns of two Green Ratsnakes (Senticolis triaspis) in the Chiricahua Mountains, Arizona. Herpetological Review 37(1):34-37.

Author: Jim Rorabaugh

For more information on this species, please see the following volume and page in the Sonoran Herpetologist: 2009 Sep:100.

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