Montana Snakes: Identification Guide With Pictures

Last checked November 3, 2026 against official sources.

On this page

Venomous snakes
The other 9 snakes
Lookalikes
When they are active
If you are bitten or stung
How to report
What official sources say
About this list
Sources

Montana Fish, Wildlife & Parks: Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.

This page lists 10 snakes: all from Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide's Montana Field Guide: Reptiles; FWP: Living with Snakes. 1 is venomous by official accounts: Prairie Rattlesnake.

Venomous snakes in Montana

Official sources label these snakes venomous in Montana. Venomous snakes in Montana has more on each one.

Prairie Rattlesnake

Crotalus viridis

Venomous per Montana State University Extension

Danger to people

“On rare occasions, rattlesnake bites have caused severe injury – even death.” Montana State University Extension

Size

Usually about 3 to 4 feet; Montana gives 15 to 60 inches and NPS says up to 5 feet. Arizona gives a maximum of 28 to 64 inches (excluding rattle) depending on subspecies; in Colorado it is rarely over 39 inches.

How to recognize it

Rattle (or a button in newborns) at the tail tip
Head much broader than the neck, many small scales on top of the head, heat-sensing pit between eye and nostril
Vertical (cat-like) pupils

Where in Montana

Prairie Rattlesnakes occur throughout Montana, typically below 6,500 feet Montana State University Extension

Conservation

State Rank S4; FWP SWAP: SGCN

48 records by month.

What the sources say

Venom: “Montana only has 10 native snake species, of which, only the Prairie Rattlesnake (Crotalus viridis) is venomous.” (Montana State University Extension)

Habitat: Favor open and arid country but are also found in ponderosa pine stands and mixed grass-coniferous forests (Montana State University Extension)

Full Prairie Rattlesnake guide

The other 9 snakes

From A to Z. Some harmless snakes mimic venomous ones: leave every snake alone.

Common Gartersnake

Thamnophis sirtalis

Non-venomous per Montana Fish, Wildlife & Parks

Conservation: State Rank S5

44 records by month.

What the sources say

Venom: “Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.” (Montana Fish, Wildlife & Parks)

Habitat: Common Gartersnakes are found in nearly all habitats, but most commonly at lower elevations around water. (Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide)

Gophersnake

Pituophis catenifer

Non-venomous per Montana Fish, Wildlife & Parks

Size

Usually 3 to 6 feet; Arizona's longest snake, up to 92 inches (AZGFD); Missouri record 105 inches

How to recognize it

No rattle: tail tapers to a point
Round pupils; keeled back scales (separates it from the similar glossy snake)
Head somewhat triangular, more so when agitated (so head shape alone is not a safe test)

Conservation

State Rank S5

58 records by month.

What the sources say

Venom: “Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.” (Montana Fish, Wildlife & Parks)

Habitat: Gophersnakes are associated with dry habitats, including open pine forests. (Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide)

Full Gophersnake guide

North American Racer

Coluber constrictor

Non-venomous per Montana Fish, Wildlife & Parks

Size

Most adults about 3 to 5 ft. Sources range from 20 to 56 inches (Florida Museum) to 34 to 77 inches (New Jersey); Alabama says some exceed 6 ft.

How to recognize it

Smooth scales
Long and slender with large eyes
White chin

Conservation

State Rank S5

30 records by month.

What the sources say

Venom: “Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.” (Montana Fish, Wildlife & Parks)

Full North American Racer guide

Northern Rubber Boa

Charina bottae

Non-venomous per Montana Fish, Wildlife & Parks

Size

In the Northwest it rarely exceeds about two feet (WDFW). Montana: 14 to 28 inches total length; Yellowstone gives a maximum of 28 inches; Colorado gives a maximum of about 33 inches.

How to recognize it

Thick body, small eyes, tiny scales, and a blunt tail that looks like the head
Loose, wrinkled skin gives a rubbery look and feel
Small, smooth scales, almost velvety to the touch

Where in Montana

Currently, this species has been documented in 26 Counties in Montana and the most eastern record in the state is in Rosebud County (MTNHP 2023). Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide

Conservation

State Rank S4; FWP SWAP: SGCN

What the sources say

Venom: “Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.” (Montana Fish, Wildlife & Parks)

Habitat: Northern Rubber Boa are secretive, slow-moving, docile snakes. (Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide)

Full Northern Rubber Boa guide

Plains Gartersnake

Thamnophis radix

Non-venomous per Montana Fish, Wildlife & Parks

Conservation: State Rank S5

What the sources say

Venom: “Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.” (Montana Fish, Wildlife & Parks)

Habitat: Plains Gartersnakes are found in nearly all habitats, but most commonly at lower elevations around water. (Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide)

Plains Hog-nosed Snake

Heterodon nasicus

Non-venomous per Montana Fish, Wildlife & Parks

Danger to people: “The Western Hog-nosed Snake contains slightly toxic saliva secretions, which have caused mild envenomations in some humans” Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide
Where in Montana: Currently in Montana, there are about 244 records from 26 counties east of the Continental Divide (MTNHP 2024). Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide
Conservation: Species of Concern; State Rank S2; BLM: SENSITIVE; FWP SWAP: SGCN

What the sources say

Venom: “Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.” (Montana Fish, Wildlife & Parks)

Habitat: The Western Hog-nosed Snake prefers plains and savannahs with well drained sandy or gravelly soil where it can easily burrow or dig out prey. (Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide)

Smooth Greensnake

Opheodrys vernalis

Non-venomous per Montana Fish, Wildlife & Parks

Conservation: Species of Concern; State Rank S2; BLM: SENSITIVE; FWP SWAP: SGCN

What the sources say

Venom: “Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.” (Montana Fish, Wildlife & Parks)

Habitat: Smooth Greensnakes prefer mesic habitat such as wet prairies, meadows, marshes, open forests, and riparian corridors with lush shrubby and herbaceous cover. (Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide)

Terrestrial Gartersnake

Thamnophis elegans

Non-venomous per Montana Fish, Wildlife & Parks

Conservation: State Rank S5

What the sources say

Venom: “Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.” (Montana Fish, Wildlife & Parks)

Habitat: Terrestrial Gartersnakes are found in nearly all habitats, but most commonly at lower elevations around water. (Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide)

Western Milksnake

Lampropeltis gentilis

Non-venomous per Montana Fish, Wildlife & Parks

Conservation: Species of Concern; State Rank S2; BLM: SENSITIVE; FWP SWAP: SGCN

What the sources say

Venom: “Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.” (Montana Fish, Wildlife & Parks)

Habitat: Little specific information is available. (Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide)

Snakes people confuse

Rubber Boa or Racer (Western Yellow-bellied Racer)?

Rubber Boa Non-venomous

Racer (Western Yellow-bellied Racer) Non-venomous

WDFW: racers have large eyes, large back scales and a tail that tapers to a point; rubber boas have small eyes, tiny scales and a blunt tail. Racers are fast and will strike and bite if cornered or handled; rubber boas are slow and non-aggressive. Yellowstone adds that racers have round pupils.

Prairie Rattlesnake or Bullsnake (gopher snake)?

Prairie Rattlesnake Venomous

Bullsnake (gopher snake) Non-venomous

The bullsnake has no rattle, an oval or rounded head and large round pupils; the prairie rattlesnake has a triangular head, slit pupils and a rattle. Bullsnakes are often mistaken for rattlesnakes: when threatened they may coil, flatten the head, hiss and vibrate the tail in dry leaves to sound like a rattle, so do not judge by behavior or by head shape alone.

Prairie Rattlesnake or Western hognose snake?

Prairie Rattlesnake Venomous

Western hognose snake Non-venomous

The Montana Field Guide names the western hog-nosed snake as a lookalike and says that in Montana no other snake has rattles: a hognose has no rattle.

Photos show typical adults; individuals vary. Never get close to compare.

When snakes are active in Montana

Records of snakes in Montana peak in May to July. They show when people record snakes, not how many there are (about month bars).

318 records of snakes in Montana by month (GBIF, CC0 and CC BY records).

Most snakebites occur April to September. Montana State University Extension
Snakes generally inactive below 60°F. Montana State University Extension

If you are bitten or stung

Call 911 or Poison Help at 1-800-222-1222 right away. Poison Help connects you to your local poison center, any time of day.

Official advice from Montana State University Extension and Montana Fish, Wildlife & Parks:

Keep a safe distance from any snake and walk around it. Montana State University Extension
Do not try to kill a snake. Montana State University Extension
Do not handle a freshly killed snake. Montana State University Extension
FWP advice on snakes generally: leave them alone. Montana Fish, Wildlife & Parks

How to report

Boat or trailer with aquatic organisms: 1-800-TIP-MONT (1-800-847-6668). FWP main office: (406) 444-2535. Montana Fish, Wildlife & Parks

What official sources say

Are there copperheads or water moccasins in Montana?

No. FWP says the rattlesnake is the only venomous snake of Montana's 10 species; neither appears on the Field Guide list. Montana Fish, Wildlife & Parks

“Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.”

About this list

The species list comes from Montana Field Guide: Reptiles (snake families); FWP: Living with Snakes (Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide, Internet Archive captures 2025-05-06 to 2026-09-02, one per family page (each listed below)).

Venom labels come only from official sources and link to them; "Not stated" never means harmless. How labels work.

Sources

Contact Us. Montana Fish, Wildlife & Parks. archived copy, captured October 19, 2026; checked November 3, 2026.
Montana Field Guide: Reptiles and Amphibians (family species lists). Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide. archived copy, captured May 6, 2025; checked November 3, 2026.
Living with Snakes. Montana Fish, Wildlife & Parks. archived copy, captured May 18, 2026; checked November 3, 2026.
Quoted passages (2)
“Of the 10 species of snakes found in Montana only the western rattlesnake is poisonous.”
“If you have a problem with snakes, the best advice is to just leave them alone.”
Plains Hog-nosed Snake - Heterodon nasicus. Montana Natural Heritage Program (Montana State Library) with Montana Fish, Wildlife & Parks: Montana Field Guide. archived copy, captured February 8, 2026; checked November 3, 2026.
Quoted passages (1)
“The Western Hog-nosed Snake contains slightly toxic saliva secretions, which have caused mild envenomations in some humans”
Rattlesnake Safe in Montana (MontGuide MT202201AG). Montana State University Extension. Revised January 2022; checked November 3, 2026.
Quoted passages (7)
“Montana only has 10 native snake species, of which, only the Prairie Rattlesnake (Crotalus viridis) is venomous.”
“On rare occasions, rattlesnake bites have caused severe injury – even death.”
“If you encounter a snake, simply maintain a safe distance (three times the body length) and walk around, allowing plenty of space.”
“Do not attempt to kill the snake, as many bites occur during the process.”
“Do not handle a freshly-killed snake, as it can still inject venom for some time following death.”
“Most bites occur between the months of April and September when snakes and humans are most active outdoors.”
“Snakes are generally not active when temperatures dip below 60° F.”
Report a suspected AIS. Montana Fish, Wildlife & Parks. archived copy, captured May 3, 2026; checked November 3, 2026.
Quoted passages (1)
“If you see a boat or trailer with aquatic organisms attached to it, call 1-800-TIP-MONT (1-800-847-6668) immediately.”
GBIF.org occurrence records, human observations licensed CC0 1.0 or CC BY 4.0 only, accessed November 3, 2026. The datasets behind these counts are listed on our Sources page.