Snakes in Iowa
Iowa has 22 snake species on record, each with at least 10 GBIF records in the state, and 1,054 licensed records in all. The most recorded are the plains garter snake, the common garter snake and the northern water snake. Three of them are venomous.
Rattlesnakes in Iowa
Rattlesnakes: three species are listed for Iowa, with 69 records (7% of the state's snake records). The most recorded is the timber rattlesnake (35), ahead of the prairie rattlesnake (20).
Most licensed records of the timber rattlesnake in Iowa come from Madison County, Lee County and Johnson County.
Water snakes and swamp snakes in Iowa
Water snakes and swamp snakes: two species are listed for Iowa, with 123 records (12% of the state's snake records). The most recorded is the northern water snake (104), ahead of the Graham's crayfish snake (19).
Most licensed records of the northern water snake in Iowa come from Adams County, Johnson County and Polk County.
Garter snakes and ribbon snakes in Iowa
Garter snakes and ribbon snakes dominate the snake record of Iowa: three species and 36% of all records. The most recorded is the plains garter snake (213), ahead of the common garter snake (156).
Observation records of the plains garter snake in Iowa run mostly May through October, peaking in May; most licensed records come from Dickinson County, Palo Alto County and Kossuth County. Observation records of the common garter snake in Iowa run mostly March through September, peaking in April; most licensed records come from Johnson County, Dickinson County and Woodbury County.
Rat snakes and corn snakes in Iowa
Rat snakes and corn snakes: three species are listed for Iowa, with 102 records (10% of the state's snake records). The most recorded is the eastern fox snake (48), ahead of the western foxsnake (40).
Most licensed records of the eastern fox snake in Iowa come from Story County, Jones County and Woodbury County. Observation records of the western foxsnake in Iowa run mostly May through October, peaking in May; most licensed records come from Woodbury County, Warren County and Plymouth County.
Kingsnakes and milksnakes in Iowa
Kingsnakes and milksnakes: two species are listed for Iowa, with 45 records (4% of the state's snake records). The most recorded is the eastern milksnake (29), ahead of the prairie kingsnake (16).
Racers, whipsnakes and indigo snakes in Iowa
One species of this group is listed for Iowa: the eastern racer, with 59 records (6% of the state's snake records).
Most licensed records of the eastern racer in Iowa come from Madison County, Story County and Woodbury County.
Gopher snakes, bullsnakes and pine snakes in Iowa
One species of this group is listed for Iowa: the gopher snake, with 83 records (8% of the state's snake records).
Most licensed records of the gopher snake in Iowa come from Woodbury County, Guthrie County and Story County.
Hognose snakes in Iowa
One species of this group is listed for Iowa: the eastern hog-nosed snake, with 19 records (2% of the state's snake records).
Green snakes in Iowa
One species of this group is listed for Iowa: the smooth green snake, with 39 records (4% of the state's snake records).
Most licensed records of the smooth green snake in Iowa come from Woodbury County, Buchanan County and Johnson County.
Small woodland and burrowing snakes in Iowa
Small woodland and burrowing snakes: five species are listed for Iowa, with 107 records (10% of the state's snake records). The most recorded is the DeKay's brown snake (51), ahead of the ring-necked snake (30).
Observation records of the DeKay's brown snake in Iowa run mostly March through October, peaking in October; most licensed records come from Linn County, Johnson County and Black Hawk County. Most licensed records of the ring-necked snake in Iowa come from Woodbury County, Madison County and Jones County.
Where in Iowa are snakes recorded most?
Woodbury County leads with 81 records (8%), followed by Madison County and Dickinson County; the top five counties hold 32% of the total. 93 of Iowa's 99 counties have at least one licensed snake record.
| # | County | Records | Share |
|---|---|---|---|
| 1 | Woodbury County | 81 | 7.7% |
| 2 | Madison County | 71 | 6.7% |
| 3 | Dickinson County | 70 | 6.6% |
| 4 | Johnson County | 59 | 5.6% |
| 5 | Polk County | 59 | 5.6% |
| 6 | Adams County | 51 | 4.8% |
| 7 | Story County | 36 | 3.4% |
| 8 | Plymouth County | 34 | 3.2% |
| 9 | Palo Alto County | 33 | 3.1% |
| 10 | Kossuth County | 32 | 3.0% |
| 11 | Linn County | 24 | 2.3% |
| 12 | Van Buren County | 24 | 2.3% |
When do snakes come out in Iowa?
Observation records of snakes in Iowa run mostly April through October, peaking in May with 32% of them. December through February together hold under 2% of the records, so snakes in Iowa are rarely recorded in winter. The sharpest rise comes from April to May.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 0% | 0% | 3% | 12% | 32% | 14% | 6% | 12% | 10% | 9% | 2% | 0% |
Snakes: Iowa compared with its neighbors
Iowa ranks 26th of 50 states by the number of snake species listed; Texas leads with 86 species.
Of the six states bordering Iowa, Missouri, Illinois and Nebraska list more snake species (Iowa: 22 species; Missouri 36, Illinois 33, Nebraska 31, South Dakota 16, Wisconsin 16, Minnesota 15).
What snakes are in Iowa? All 22 species
Ranked by licensed records in Iowa. Species with a profile page are linked.
| # | Species | Family | Records | Share |
|---|---|---|---|---|
| 1 | Plains garter snake Thamnophis radix | Colubridae | 213 | 20.2% |
| 2 | Common garter snake Thamnophis sirtalis | Colubridae | 156 | 14.8% |
| 3 | Northern water snake Nerodia sipedon | Colubridae | 104 | 9.9% |
| 4 | Gopher snake Pituophis catenifer | Colubridae | 83 | 7.9% |
| 5 | Eastern racer Coluber constrictor | Colubridae | 59 | 5.6% |
| 6 | DeKay's brown snake Storeria dekayi | Colubridae | 51 | 4.8% |
| 7 | Eastern fox snake Pantherophis vulpinus | Colubridae | 48 | 4.6% |
| 8 | Western foxsnake Pantherophis ramspotti | Colubridae | 40 | 3.8% |
| 9 | Smooth green snake Opheodrys vernalis | Colubridae | 39 | 3.7% |
| 10 | Timber rattlesnake venomous Crotalus horridus | Viperidae | 35 | 3.3% |
| 11 | Ring-necked snake Diadophis punctatus | Colubridae | 30 | 2.8% |
| 12 | Eastern milksnake Lampropeltis triangulum | Colubridae | 29 | 2.8% |
| 13 | Prairie rattlesnake venomous Crotalus viridis | Viperidae | 20 | 1.9% |
| 14 | Eastern hog-nosed snake Heterodon platirhinos | Colubridae | 19 | 1.8% |
| 15 | Graham's crayfish snake Regina grahamii | Colubridae | 19 | 1.8% |
| 16 | Prairie kingsnake Lampropeltis calligaster | Colubridae | 16 | 1.5% |
| 17 | Eastern massasauga venomous Sistrurus catenatus | Viperidae | 14 | 1.3% |
| 18 | Western rat snake Pantherophis obsoletus | Colubridae | 14 | 1.3% |
| 19 | Lined snake Tropidoclonion lineatum | Colubridae | 13 | 1.2% |
| 20 | Red-bellied snake Storeria occipitomaculata | Colubridae | 9 | 0.9% |
| 21 | Western ribbon snake Thamnophis proximus | Colubridae | 9 | 0.9% |
| 22 | Smooth earth snake Virginia valeriae | Colubridae | 4 | 0.4% |
Also recorded in Iowa, fewer than 10 times
Beyond the main list, eight snake species are known from Iowa 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. Venomous among them: western massasauga and eastern copperhead.
Related pages
GBIF records read 2026-09-29. Listed: any license. Counted: CC0/CC BY only. How we count.