Snakes in Wisconsin
Wisconsin has 16 snake species on record, each with at least 10 GBIF records in the state, and 985 licensed records in all. The most recorded are the common garter snake, the northern water snake and the eastern fox snake. Two of them are venomous.
Rattlesnakes in Wisconsin
Rattlesnakes: two species are listed for Wisconsin, with 58 records (6% of the state's snake records). The most recorded is the timber rattlesnake (46), ahead of the eastern massasauga (12).
Most licensed records of the timber rattlesnake in Wisconsin come from Sauk County, Pepin County and Grant County.
Water snakes and swamp snakes in Wisconsin
One species of this group is listed for Wisconsin: the northern water snake, with 80 records (8% of the state's snake records).
Observation records of the northern water snake in Wisconsin run mostly May through September, peaking in May; most licensed records come from Washburn County, Juneau County and Crawford County.
Garter snakes and ribbon snakes in Wisconsin
Garter snakes and ribbon snakes dominate the snake record of Wisconsin: three species and 52% of all records. The most recorded is the common garter snake (469), ahead of the plains garter snake (24).
Observation records of the common garter snake in Wisconsin run mostly April through October, peaking in May; most licensed records come from Winnebago County, Juneau County and Dane County.
Rat snakes and corn snakes in Wisconsin
Rat snakes and corn snakes: two species are listed for Wisconsin, with 79 records (8% of the state's snake records). The most recorded is the eastern fox snake (78), ahead of the eastern rat snake (1).
Observation records of the eastern fox snake in Wisconsin run mostly April through September, peaking in May; most licensed records come from Door County, Dunn County and Green Lake County.
Kingsnakes and milksnakes in Wisconsin
One species of this group is listed for Wisconsin: the eastern milksnake, with 26 records (3% of the state's snake records).
Racers, whipsnakes and indigo snakes in Wisconsin
One species of this group is listed for Wisconsin: the eastern racer, with 6 records (0.6% of the state's snake records).
Gopher snakes, bullsnakes and pine snakes in Wisconsin
One species of this group is listed for Wisconsin: the gopher snake, with 15 records (2% of the state's snake records).
Hognose snakes in Wisconsin
One species of this group is listed for Wisconsin: the eastern hog-nosed snake, with 25 records (3% of the state's snake records).
Green snakes in Wisconsin
One species of this group is listed for Wisconsin: the smooth green snake, with 27 records (3% of the state's snake records).
Small woodland and burrowing snakes in Wisconsin
Small woodland and burrowing snakes: three species are listed for Wisconsin, with 141 records (14% of the state's snake records). The most recorded is the red-bellied snake (73), ahead of the DeKay's brown snake (60).
Observation records of the red-bellied snake in Wisconsin run mostly April through October, peaking in October; most licensed records come from Dane County, Waukesha County and Juneau County. Observation records of the DeKay's brown snake in Wisconsin run mostly April through October, peaking in October; most licensed records come from Juneau County, Dane County and Grant County.
Where in Wisconsin are snakes recorded most?
Winnebago County leads with 101 records (10%), followed by Juneau County and Sauk County; the top five counties hold 38% of the total. 66 of Wisconsin's 72 counties have at least one licensed snake record.
| # | County | Records | Share |
|---|---|---|---|
| 1 | Winnebago County | 101 | 10.3% |
| 2 | Juneau County | 85 | 8.6% |
| 3 | Sauk County | 75 | 7.6% |
| 4 | Dane County | 72 | 7.3% |
| 5 | Vilas County | 45 | 4.6% |
| 6 | Door County | 40 | 4.1% |
| 7 | Waukesha County | 39 | 4.0% |
| 8 | Racine County | 35 | 3.6% |
| 9 | Dodge County | 30 | 3.0% |
| 10 | Grant County | 30 | 3.0% |
| 11 | Dunn County | 25 | 2.5% |
| 12 | Milwaukee County | 24 | 2.4% |
When do snakes come out in Wisconsin?
Observation records of snakes in Wisconsin run mostly April through October, peaking in May with 20% of them. December through February together hold under 2% of the records, so snakes in Wisconsin are rarely recorded in winter. The sharpest rise comes from March to April.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0% | 0% | 2% | 12% | 20% | 14% | 16% | 12% | 13% | 10% | 1% | 0% |
Snakes: Wisconsin compared with its neighbors
Wisconsin ranks 33rd of 50 states by the number of snake species listed, level with Oregon and South Dakota; Texas leads with 86 species.
Of the four states bordering Wisconsin, Illinois, Iowa and Michigan list more snake species (Wisconsin: 16 species; Illinois 33, Iowa 22, Michigan 17, Minnesota 15).
What snakes are in Wisconsin? All 16 species
Ranked by licensed records in Wisconsin. Species with a profile page are linked.
| # | Species | Family | Records | Share |
|---|---|---|---|---|
| 1 | Common garter snake Thamnophis sirtalis | Colubridae | 469 | 47.6% |
| 2 | Northern water snake Nerodia sipedon | Colubridae | 80 | 8.1% |
| 3 | Eastern fox snake Pantherophis vulpinus | Colubridae | 78 | 7.9% |
| 4 | Red-bellied snake Storeria occipitomaculata | Colubridae | 73 | 7.4% |
| 5 | DeKay's brown snake Storeria dekayi | Colubridae | 60 | 6.1% |
| 6 | Timber rattlesnake venomous Crotalus horridus | Viperidae | 46 | 4.7% |
| 7 | Smooth green snake Opheodrys vernalis | Colubridae | 27 | 2.7% |
| 8 | Eastern milksnake Lampropeltis triangulum | Colubridae | 26 | 2.6% |
| 9 | Eastern hog-nosed snake Heterodon platirhinos | Colubridae | 25 | 2.5% |
| 10 | Plains garter snake Thamnophis radix | Colubridae | 24 | 2.4% |
| 11 | Butler's garter snake Thamnophis butleri | Colubridae | 22 | 2.2% |
| 12 | Gopher snake Pituophis catenifer | Colubridae | 15 | 1.5% |
| 13 | Eastern massasauga venomous Sistrurus catenatus | Viperidae | 12 | 1.2% |
| 14 | Ring-necked snake Diadophis punctatus | Colubridae | 8 | 0.8% |
| 15 | Eastern racer Coluber constrictor | Colubridae | 6 | 0.6% |
| 16 | Eastern rat snake Pantherophis alleghaniensis | Colubridae | 1 | 0.1% |
Also recorded in Wisconsin, fewer than 10 times
Beyond the main list, two snake species are known from Wisconsin by only 3 to 9 records each. Some are genuine rarities at the edge of their range; others may be strays, released pets or old misidentifications, so treat them as unconfirmed.
Related pages
GBIF records read 2026-09-29. Listed: any license. Counted: CC0/CC BY only. How we count.