Plains garter snake (Thamnophis radix)
The plains garter snake is a snake in the family Colubridae with a mild venom for its prey, not dangerous to people. GBIF holds 2,706 licensed U.S. records of it; it reaches our listing threshold in 16 states, most of all Kansas (562), South Dakota (514) and Nebraska (431). Its observation records peak in May.
The plains garter snake (Thamnophis radix) is a species of garter snake native to most of the central United States as far north as Canada and as far south as Texas. It has a distinctive orange or yellow stripe from its head to tail, and the rest of its body is mainly a gray-green color. The snake is commonly found living near water sources such as streams and ponds, but can also be found in urban areas and vacant lots.
From Wikipedia: Plains garter snake, text under CC BY-SA 4.0.
Is the plains garter snake poisonous or venomous?
Mildly venomous but not dangerous: the plains garter snake has enlarged rear teeth and a mild venom for its prey, and a bite causes at most local swelling, which is why many sources simply call it harmless. It is not a pit viper or coral snake, the only U.S. land snakes with medically dangerous venom. Clean any bite like a small wound.
Which states have the plains garter snake?
Records are spread over 16 states; the top three, Kansas, South Dakota and Nebraska, hold 56% of them. It is the most recorded snake of all in Nebraska, Iowa and North Dakota.
| # | State | Records | Share of state snakes | Rank in state |
|---|---|---|---|---|
| 1 | Kansas | 562 | 3.8% | 8th of 44 |
| 2 | South Dakota | 514 | 16.1% | 3rd of 16 |
| 3 | Nebraska | 431 | 18.3% | 1st of 31 |
| 4 | Colorado | 262 | 7.5% | 4th of 26 |
| 5 | Illinois | 250 | 9.0% | 4th of 33 |
| 6 | Iowa | 213 | 20.2% | 1st of 22 |
| 7 | North Dakota | 104 | 48.1% | 1st of 8 |
| 8 | Oklahoma | 75 | 0.6% | 37th of 50 |
| 9 | Minnesota | 58 | 6.3% | 3rd of 15 |
| 10 | Wyoming | 46 | 4.3% | 5th of 11 |
| 11 | Montana | 45 | 3.5% | 6th of 9 |
| 12 | New Mexico | 37 | 0.6% | 27th of 56 |
| 13 | Indiana | 30 | 1.4% | 17th of 27 |
| 14 | Missouri | 30 | 1.6% | 19th of 36 |
| 15 | Wisconsin | 24 | 2.4% | 10th of 16 |
| 16 | Ohio | 11 | 0.2% | 24th of 25 |
When is the plains garter snake seen?
Across the U.S., observation records of the plains garter snake run mostly April through October, peaking in May with 18% of them. Almost none are from December to February.
Season by state
Among states whose main season falls within one calendar year, it starts earliest in March (Illinois) and latest in June (Minnesota). The most common peak month is June, shared by Colorado, Kansas, Nebraska and South Dakota.
| State | Main season | Peak month | Observation records |
|---|---|---|---|
| Illinois | March through September | April | 139 |
| South Dakota | April through October | June | 99 |
| Colorado | May through October | June | 93 |
| Nebraska | April through October | June | 90 |
| Kansas | May through November | June | 37 |
| Iowa | May through October | May | 36 |
| Minnesota | June through October | July | 30 |
Where the plains garter snake is recorded in each state
Kansas
Kansas holds 562 licensed records, the 8th most recorded of 44 snakes listed there. Its observation records in Kansas run mostly May through November, peaking in June; most licensed records come from Barton County, Ellis County and Douglas County. Next come Russell County (40) and Meade County (30).
South Dakota
South Dakota holds 514 licensed records, the 3rd most recorded of 16 snakes listed there. Its observation records in South Dakota run mostly April through October, peaking in June; most licensed records come from Clay County, Brookings County and Union County. Next come Pennington County (27) and Jackson County (25).
Nebraska
Nebraska holds 431 licensed records, the most recorded of 31 snakes listed there. Its observation records in Nebraska run mostly April through October, peaking in June; most licensed records come from Sioux County, Garden County and Sheridan County. Next come Custer County (22) and Merrick County (22).
Colorado
Colorado holds 262 licensed records, the 4th most recorded of 26 snakes listed there. Its observation records in Colorado run mostly May through October, peaking in June; most licensed records come from Boulder County, Larimer County and Adams County. Next come Denver County (23) and El Paso County (19).
Illinois
Illinois holds 250 licensed records, the 4th most recorded of 33 snakes listed there. Its observation records in Illinois run mostly March through September, peaking in April; most licensed records come from Cook County, Lake County and Will County. Next come Champaign County (39) and DuPage County (12).
Iowa
Iowa holds 213 licensed records, the most recorded of 22 snakes listed there. Its observation records in Iowa run mostly May through October, peaking in May; most licensed records come from Dickinson County, Palo Alto County and Kossuth County. Next come Woodbury County (24) and Story County (9).
North Dakota
North Dakota holds 104 licensed records, the most recorded of 8 snakes listed there. Most of its licensed records in North Dakota come from Sheridan County, Ward County and McKenzie County. Next come Billings County (7) and Pembina County (6).
Oklahoma
Oklahoma holds 75 licensed records, the 37th most recorded of 50 snakes listed there. Most of its licensed records in Oklahoma come from Cimarron County, Woodward County and Beaver County. Next come Texas County (1).
Minnesota
Minnesota holds 58 licensed records, the 3rd most recorded of 15 snakes listed there. Its observation records in Minnesota run mostly June through October, peaking in July; most licensed records come from Dakota County, Hennepin County and Anoka County. Next come Mahnomen County (3) and Polk County (3).
Wyoming
Wyoming holds 46 licensed records, the 5th most recorded of 11 snakes listed there. Most of its licensed records in Wyoming come from Laramie County, Campbell County and Goshen County. Next come Carbon County (3) and Niobrara County (2).
Montana
Montana holds 45 licensed records, the 6th most recorded of 9 snakes listed there. Most of its licensed records in Montana come from Phillips County, Roosevelt County and Valley County. Next come Carter County (4) and Custer County (4).
New Mexico
New Mexico holds 37 licensed records, the 27th most recorded of 56 snakes listed there. Most of its licensed records in New Mexico come from Harding County, Union County and Mora County. Next come San Miguel County (5) and Colfax County (5).
Indiana
Indiana holds 30 licensed records, the 17th most recorded of 27 snakes listed there. Most of its licensed records in Indiana come from Jasper County, Lake County and Benton County. Next come Newton County (2) and White County (2).
Missouri
Missouri holds 30 licensed records, the 19th most recorded of 36 snakes listed there. Most of its licensed records in Missouri come from Holt County, Buchanan County and Linn County. Next come St. Charles County (1) and St. Louis County (1).
Top counties in the U.S.
| # | County | State | Records | Share of U.S. |
|---|---|---|---|---|
| 1 | Clay County | South Dakota | 82 | 3.0% |
| 2 | Barton County | Kansas | 72 | 2.7% |
| 3 | Cimarron County | Oklahoma | 71 | 2.6% |
| 4 | Cook County | Illinois | 68 | 2.5% |
| 5 | Ellis County | Kansas | 63 | 2.3% |
| 6 | Sioux County | Nebraska | 62 | 2.3% |
| 7 | Lake County | Illinois | 61 | 2.3% |
| 8 | Boulder County | Colorado | 60 | 2.2% |
| 9 | Dickinson County | Iowa | 58 | 2.1% |
| 10 | Garden County | Nebraska | 55 | 2.0% |
| 11 | Larimer County | Colorado | 43 | 1.6% |
| 12 | Will County | Illinois | 42 | 1.6% |
| 13 | Douglas County | Kansas | 42 | 1.6% |
| 14 | Russell County | Kansas | 40 | 1.5% |
| 15 | Champaign County | Illinois | 39 | 1.4% |
How recent are the plains garter snake records?
The plains garter snake record leans on older material: only 27% of dated U.S. records come from 2017–2026, and the median record is from 1970. The oldest dated record is from 1853; the busiest year was 2023, with 99 records.
| Decade | Records | Share |
|---|---|---|
| 1850s | 19 | 0.8% |
| 1860s | 1 | 0.0% |
| 1870s | 18 | 0.7% |
| 1880s | 8 | 0.3% |
| 1890s | 24 | 1.0% |
| 1900s | 61 | 2.5% |
| 1910s | 48 | 2.0% |
| 1920s | 188 | 7.7% |
| 1930s | 176 | 7.2% |
| 1940s | 167 | 6.9% |
| 1950s | 236 | 9.7% |
| 1960s | 256 | 10.5% |
| 1970s | 133 | 5.5% |
| 1980s | 88 | 3.6% |
| 1990s | 20 | 0.8% |
| 2000s | 141 | 5.8% |
| 2010s | 315 | 13.0% |
| 2020s | 533 | 21.9% |
Species recorded in the same counties
Of the 164 counties where the plains garter snake is most recorded, 74 are also top counties for the gopher snake, more than for any other snake. Venomous species among its neighbors: the prairie rattlesnake.
| Species | Shared counties |
|---|---|
| Gopher snake | 74 |
| Common garter snake | 58 |
| Eastern racer | 52 |
| Prairie rattlesnake venomous | 41 |
| Plains hog-nosed snake | 31 |
| Northern water snake | 28 |
| DeKay's brown snake | 23 |
| Ring-necked snake | 18 |
Related species in the U.S.
Other species of the genus Thamnophis with profiles here: Western terrestrial garter snake, Common garter snake, Western ribbon snake, Aquatic garter snake, Northwestern garter snake, Western aquatic garter snake, Checkered garter snake and Eastern ribbonsnake.
GBIF records read 2026-09-29. Listed: any license. Counted: CC0/CC BY only. How we count.