Image © Suzanne L. Collins, CNAH.
Adult from Meade County. Image © Suzanne L. Collins, CNAH.
An adult Common Gartersnake from Seward County. © Suzanne L. Collins, CNAH.
An adult Common Gartersnake from Lincoln County, Kansas. © Kevin Urbanek.
Common Gartersnake eating an American Bullfrog in Barton County, Kansas. © Ariel Snyder.
An adult Common Gartersnake from Pottawatomie County. Image © Jacob Basler.
A young adult Common Gartersnake from Meade County, Kansas. Image © John Tollefson.
An adult from Pratt County. Image © Ken Brunson.
An adult from Barton County. Image © Suzanne L. Collins, CNAH.
An adult Common Gartersnake from Seward County. © Suzanne L. Collins, CNAH.
An adult from Cherokee County, Kansas. Image © Suzanne L. Collins, CNAH.
REPTILIA (Reptiles) SQUAMATA (PART) (Snakes) NATRICIDAE (Harmless Egg-Retaining Snakes)

Common Gartersnake
Thamnophis sirtalis (Linnaeus 1758)
thăm-nō-fĭs — sĭr-tāl-ŭs


Conservation Status:

State: None

Federal: None
NatureServe State: S5 - Secure
NatureServe National: N5 - Secure
NatureServe Global: G5 - Secure
CITES: None
Diagnosis:
HARMLESS. The pattern/color of this snake is variable. In general the Common Gartersnake is characterized by keeled scales, a single anal scale, a stripe on each side of the body situated on the second and third scale rows (counting from the belly up), absence of a crescent-shaped mark behind the angle of the jaw, and a pattern of two rows of alternating black spots on a between the stripes on the back. The belly is white, greenish, or gray, with a row of small dark spots along its edges. Adult males have longer tails than females, but females are larger than males.
The dorsal stripe may vary in the intensity of its coloration, but is usually well-defined and not encroached upon by adjacent lateral blotches. On specimens with orange or red dorsal stripes, the coloration usually starts with yellow or orange near the head and quickly transitions to the tip of the tail. The lateral stripes are less distinct and situated on second and third scale rows (counting from belly up) anteriorly. Between the stripes are two longitudinal rows of offset squarish black blotches producing a checkerboard pattern on a red (most wide-spread; parietalis type; 'red-sided' variant), yellow, green, or blue background. The belly is white, greenish, or gray, with a row of small dark spots along the edges.
Specimens from the extreme southwestern portion of their range in Kansas (Meade and Seward counties; annectens type; 'red-striped' variant) have a tan, black, yellow, or green alternating with the black blotches between the stripes. The dorsal stripe is bright red to orange. Some specimens from the Ozark Plateau of Cherokee County (sirtalis type; 'eastern' variant) have a muted pattern and color with an orange vertebral stripe and no lateral red markings.
The labials are heavily barred along their sutures and the posterior labials match the anterior labials in color. There may or may not be pair of light spots on top of the head along the suture of the parietal scales.
The young look like miniature adults with subdued coloration. Females have relatively larger heads.
Adults normally attain 41.0-71.0 cm (16-28 inches) in total length. The largest specimen from Kansas is a female (KU 189179) from Reno County with a total length of 113.0 cm (44½ inches) collected by George Ratzlaff on 5 March 1981. The maximum length throughout the range is 132.1 cm (52 inches) (Boundy, 1995; Powell et al., 2016). The maximum weight for a Kansas specimen is 410 grams (14½ ounces).

Distribution:
Common throughout the eastern two-thirds of Kansas. Enters western Kansas along riparian corridors where it is seldom found far from them.Records mapped by Collins (1982) have since been reidentified (Hamilton County) or discredited/uncorroborated (Wallace County) (see Collins 1984)
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Full range depicted by light shaded red area. Export Google Earth (.kml)
  • Occurrence Summary:  
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    Records 
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    Other Observations 
Some county occurrences indicated below may be too imprecise to map above.
County Breakdown: County Name (# occurrences):


Fossil History:
Fossils from the Williams Local Fauna of Rice County (Pleistocene: Illinoian) (Preston 1979; Holman 1984; Holman 1995), Kanopolis Local Fauna of Ellsworth County (Pleistocene: Rancholabrean I) (Preston 1979, Holman 1972, Holman 1984; Holman 1995), Cragin Quarry Local Fauna of Meade County (Pleistocene: Sangamonian) (Hay 1917; Etheridge 1958; Etheridge 1960, Tihen 1960; Tihen 1962; Brattstrom 1967; Preston 1979; Holman 1995) (species indeterminate), and Courtland Canal/Hall Ash local fauna of Jewell County (Rogers, 1982; Eshelman and Hager, 1984) are referable to this taxon.

Natural History:
Fitch and Maslin (1961) and Fitch (1965) studied this snake on the Great Plains, and much of the information from Kansas is based on their observations.
The Common Gartersnake is found in a wide variety of habitats, including marshes and wet meadows, margins of ponds, woodland and woodland edge, floodplains, and cultivated fields. It generally prefers areas with moderately moist vegetation. Platt (1985) found this reptile more common in the sand prairie habitat of western Harvey County than in the eastern part which lacked this habitat.
This hardy species is active from March to November at air temperatures ranging from 55° to 100°F. During warm periods from December to February, it frequently emerges from its underground winter retreats. Although this snake is active over a wide range of time and air temperatures, it appears to prefer air temperatures around 85°F.
Common Gartersnakes are active during the day and have a home range of 22- 35 acres. Estimates indicate a population density as high as three of these snakes per acre in northeastern Kansas (Fitch, 1982).
This snake mates during early spring and occasionally in the fall. On the first warm spring days, males search actively for females, locating them by scent. Several males may court the same female. The males lie alongside the female, their bodies rhythmically writhing. A successful male curls his tail beneath that of the passive female until his cloaca meets hers. Copulation occurs, and the female may drag the male along as she crawls.
Females give birth to young in late summer or fall. Litters are quite large in this species; the number of young per litter varies from four to 85 (Fitch, 1985), with an average of twenty. Collins (1974) recorded three females from Douglas County giving birth to 33, 35, and 35 young, respectively, during late July and August, the normal time of birth.
The Common Gartersnake feeds chiefly on frogs and earthworms but will also occasionally eat toads, small mice, and other small snakes. Henderson (1974) reported that examples of this snake from Douglas and Harvey counties fed almost exclusively on frogs.
Predators of this snake include hawks, large snakes, and mammals. Burt (1949) reported a young Common Gartersnake trapped and eaten by a large garden spider. Fitch (2001) reported the following prey items in decreasing abundance for northeast Kansas snakes: Allolbophora caliginosa (an earthworm), Lithobates blairi, Lithobates catesbeianus, Anaxyrus americanus, Anaxyrus woodhousii, Hyla chrysoscelis/versicolor, Acris crepitans, Pseudacris maculata, and three mammals (Microtus ochrogaster, Peromyscus leucopus, and Reithrodontomys megalotis).
Capron (1985) recorded 33 of these snakes killed by swathing (mowing) machines during agricultural harvests from May to mid-July in southern Kansas. Dillenbeck (1986) discovered nine of these harmless reptiles, all deliberately killed, along the Ninnescah River in southcentral Kansas.

Occurrence Activity:
Remarks:
First reported in Kansas by Hallowell (1857) based on two specimens collected by Fort Riley surgeon William A. Hammond. The earliest available specimen (USNM 11934) was collected at Fort Riley by the post surgeon Bernard J. D. Irwin sometime during 1867.
Boundy (1999) found evidence to elevate the annectens phenotype present in north Texas and presumably (because he didn't include samples) those populations in Seward and southwest Meade counties in Kansas.
The annectens phenotype also shows up in extreme southwest Missouri and northwest Arkansas.
The annectens form was first mentioned from Kansas by Fitch (1961) and confirmed by Irwin (1992). The 'eastern' form was first mentioned from Kansas by Collins, Collins, and Taggart (2010).
Rundquist (1999) reported assumed hybridization with a captive male Thamnophis radix, however, given that long-term sperm storage and multiple paternity have been reported in T. sirtalis, there are other interpretations not considered.
Based on a captive specimen, Snider and Bowler (1992) reported a maximum longevity for this species of fourteen years.

Bibliography:
Account Last Updated:
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Travis W. Taggart © 1999-2025 — w/ Sternberg Museum of Natural History, Fort Hays State University