Plains Gartersnake - Thamnophis radix
Global Rank:
G5
State Rank:
S4
Agency Status
USFWS:
none
USFS:
none
BLM:
none
CFWCS Tier:
3
General Description
Adults range from 16 to 42 inches in length. Background color above is olive, brown, or black. This snake has an orange or yellow dorsal stripe and two greenish-yellow stripes on each side (the latter located on the third and fourth scale rows above the belly scales). It typically has black vertical bars on the upper lips.
Diagnostic Characteristics
Other garter snakes in montana have the lateral yellow lines on the second and third scale rows above the belly scales.
Distribution
Montana Range
Observations in Montana: 727
Montana CountiesBig Horn, Blaine, Carter, Cascade, Chouteau, Custer, Dawson, Fallon, Fergus, Garfield, Glacier, Hill, Judith Basin, Lewis and Clark, Liberty, McCone, Musselshell, Petroleum, Phillips, Pondera, Powder River, Prairie, Richland, Roosevelt, Rosebud, Sheridan, Stillwater, Teton, Toole, Valley, Wibaux, Yellowstone
Migration
Nonmigratory.
Habitat
Garter snakes are found in nearly all habitats, but most commonly at lower elevations around water. Females give birth to 6 to 18 live young during summer. They eat a variety of vertebrates and invertebrates (FWP). Widely distributed over shortgrass prairie, but may be esp. common near ponds/coulees.
Reproductive Characteristics
In CO, mate May-early Jun; parturition late Jul-Sep. Litter sizes 16 (2-21). In Saskatchewan may have >1yr long reproductive cycle.
Citations & Sources
- Maxell, B. A., J. K. Werner, P. Hendricks, and D. L. Flath. 2003. Herpetology in Montana: a history, status summary, checklists, dichotomous keys, accounts for native, potentially native, and exotic species, and indexed bibliography. Northwest Fauna Number 5. 138 p.