Western Terrestrial Garter Snake {Thamnophis elegans) 



Description: Adult Western Terrestrial (or Wandering) Garter Snakes are smaller in body size 

 than the Common Garter Snake, their length varying from 18-43". Three yellow longitudinal 

 stripes are present (one dorsal, two lateral), but the dorsal stripe is much narrower than that of 

 the Common Garter Snake. A distinctive feature of the Western Terrestrial Garter Snake is a 

 series of alternating black spots which run the length of the body between, and somewhat on, 

 the yellow stripes. The background color between the stripes tends to be more gray 

 compared to the dark brown found in the Common Garter Snake. The ventral surface has a 

 series of dark black/brown blotches which may cover most of the surface. The dorsal scales 

 are keeled, and there are normally 8 upper labial scales. 

 Young: The coloration of young snakes is similar to that of the adults; young are live-bom. 



Similar species: See Common and Plains Garter Snakes. 



Habitat and Habits: The habitat and habits of the Western Terrestrial Garter Snake are similar to 

 the Common Garter Snake (i.e., they are found in most habitats but are particularly common 

 around wetlands). Females give birth to 4-19 young during the summer (Stebbins 1985). 

 Records of adults from the Ashland area (Powder River County) were made between 28 June 

 and 22 July at reservoirs or along streams (Hendricks and Reichel 1996). 



Surveying: Timed sight surveys may be conducted around wetlands and riparian feeding areas or 

 at denning areas where higher concentrations of garter snakes occur, clear mornings are best 

 for surveys. Much distributional information may come from recording incidental sightings. 

 More intensive research may be done using funnel traps in combination with drift fences. 

 More intensive research and survey projects may use mark-recapture or radiotelemetry 

 techniques. 



Status: Western Terrestrial Garter Snakes are most common in the western half of Montana, and 

 are much less abundant on the plains, especially in the eastern third of the state. There are no 

 records from the northeastern quarter This species was not recorded during the 1998 

 surveys, but there were 1998 reports from Carbon and Yellowstone counties. There are only 

 about 10 records since 1995 from within the boundaries of the former Miles City District. All 

 records of garter snakes should be documented until the distribution of the three species is 

 better understood; of particular interest would be documentation of denning sites. 



Montana Natural Heritage Program rank: G5 S5. 



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