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Western Rattlesnake

Crotalus oreganus

Reptile · family Viperidae · order Squamata

  1. G1
    Critically imperiled
  2. G2
    Imperiled
  3. G3
    Vulnerable
  4. G4
    Apparently secure
  5. G5
    Secure

NatureServe global rank G5: secure[2].

Updated October 30, 2026. Published by Humblebee.

Endangered Species Act
Not listed[1]
NatureServe global rank
G5 Secure[2]
Native in
9 states[3]

The Western Rattlesnake (Crotalus oreganus) is a reptile in the viper family[4]. It is ranked Secure worldwide and is native to nine western US states[2][3].

Conservation status

NatureServe ranks the Western Rattlesnake G5 worldwide, which it labels Secure[2]. Its national rank in the United States is N5, also Secure[5]. The IUCN Red List category recorded by NatureServe is Least concern[6]. It is not listed as endangered or threatened under the US Endangered Species Act[1]. NatureServe also gives it a state rank in each of its nine states, and these differ from place to place[7].

Status Value
Endangered Species Act[1] Not listed
NatureServe global rank[2] G5 (Secure)
NatureServe US rank[5] N5 (Secure)
IUCN Red List (via NatureServe)[6] Least concern
Total population (NatureServe estimate)[8] 100,000 to >1,000,000 individuals

Where Western Rattlesnake lives

NatureServe lists this snake as native in Arizona, California, Colorado, Idaho, Nevada, Oregon, Utah, Washington and Wyoming[3]. Wyoming has the most worrying state rank listed, while Arizona, Nevada, Oregon and Washington are all ranked as secure in the state[7]. California, Colorado and Utah have no rank yet[7]. Online observers have reported it most in California, Utah, Washington, Oregon and Nevada, but those counts follow where people look and report[9].

Alaska: not recordedAKMaine: not recordedMEWisconsin: not recordedWIVermont: not recordedVTNew Hampshire: not recordedNHWashington: native, state rank S5WAIdaho: native, state rank S4IDMontana: not recordedMTNorth Dakota: not recordedNDMinnesota: not recordedMNIllinois: not recordedILMichigan: not recordedMINew York: not recordedNYMassachusetts: not recordedMAOregon: native, state rank S5ORNevada: native, state rank S5NVWyoming: native, state rank S1WYSouth Dakota: not recordedSDIowa: not recordedIAIndiana: not recordedINOhio: not recordedOHPennsylvania: not recordedPANew Jersey: not recordedNJConnecticut: not recordedCTRhode Island: not recordedRICalifornia: native, state rank SNRCAUtah: native, state rank SNRUTColorado: native, state rank SNRCONebraska: not recordedNEMissouri: not recordedMOKentucky: not recordedKYWest Virginia: not recordedWVVirginia: not recordedVAMaryland: not recordedMDDelaware: not recordedDEArizona: native, state rank S5AZNew Mexico: not recordedNMKansas: not recordedKSArkansas: not recordedARTennessee: not recordedTNNorth Carolina: not recordedNCSouth Carolina: not recordedSCDistrict of Columbia: not recordedDCOklahoma: not recordedOKLouisiana: not recordedLAMississippi: not recordedMSAlabama: not recordedALGeorgia: not recordedGAHawaii: not recordedHITexas: not recordedTXFlorida: not recordedFLPuerto Rico: not recordedPR
State presence as recorded by NatureServe[7].
Show state ranks (9 states)
StateRankMeaning
ArizonaS5Secure
CaliforniaSNRNot Ranked
ColoradoSNRNot Ranked
IdahoS4Apparently Secure
NevadaS5Secure
OregonS5Secure
UtahSNRNot Ranked
WashingtonS5Secure
WyomingS1Critically Imperiled

Habitat

NatureServe records many habitat types for this snake, including forest, woodland, shrubland, savanna, grassland, bare rock and talus, and riparian areas (land beside streams)[10]. It lives in many settings, from shrubby coastal dunes to timberline, and in open mountain forests[11]. It mostly stays on the ground but sometimes climbs into trees or shrubs[11]. When resting, it uses burrows, crevices, caves or other hidden spots[11].

Habitat types recorded by NatureServe[10]

Diet

NatureServe records the adult diet as meat only[12]. The snake eats mostly small mammals, and also birds and lizards, and rarely amphibians[13]. Young snakes in some regions eat mostly lizards[13]. Mating happens mostly from mid-summer to early fall, and young are born from August to October[14]. Litters grow larger as the mother grows larger, with an average of 5 in small subspecies and a top figure near 25 for the biggest females of the biggest subspecies[14]. The facts here give no size or lifespan figures.

Trait Value
Food habits[12] Carnivore

When to look for it

In most of its range this snake is active from about April to November[15]. In warm places such as southern California, a few may be out on the surface in every month[15]. In cool weather it is active mostly in the daytime, but in hot summer weather it is active mainly in the evening and at night[15]. NatureServe notes it hibernates[16]. Online observation records peak in April, May and June, which shows when people report it and not how many snakes there are[17].

January: 197 recordsJanFebruary: 555 recordsFebMarch: 2,316 recordsMarApril: 4,867 recordsAprMay: 6,296 recordsMayJune: 4,937 recordsJunJuly: 3,911 recordsJulAugust: 3,158 recordsAugSeptember: 2,634 recordsSepOctober: 1,578 recordsOctNovember: 469 recordsNovDecember: 160 recordsDec
US observation records on GBIF by month, all years. The three months with the most records are highlighted. Records show when people look and report, not how many animals there are[17].
Show records by month
MonthRecords
January197
February555
March2,316
April4,867
May6,296
June4,937
July3,911
August3,158
September2,634
October1,578
November469
December160

Where to see it

National Park Service species lists record Western Rattlesnake as present in 14 park units[18]. Present means the park has a confirmed record, not that sightings are common.

States with the most GBIF observation records: California, Utah, Washington, Oregon, Nevada[9]. These counts follow where people look and report, not population size.

Safety around this animal

These tips are quoted in summary from official agencies. We add no advice of our own. Follow local rules and the agency pages linked below.

From CDC / NIOSH

  • CDC lists rattlesnakes, copperheads, cottonmouths and coral snakes as the venomous snakes of the United States.
  • After a bite, get emergency medical care as soon as possible, and do not drive yourself.
  • Keep the bitten limb in a comfortable, neutral position, take off rings and watches before swelling starts, wash the bite and cover it with a clean dry dressing.
  • Do not cut the wound, suck out venom, or use a tourniquet, ice or water immersion. Do not handle the snake, even a dead one.
  • If you can do it safely, take a photo of the snake from a distance to help with identification.

Source: CDC / NIOSH[19]

Questions people ask

Is the Western Rattlesnake endangered?
No. It is not listed as endangered or threatened under the US Endangered Species Act[1]. NatureServe ranks it Secure worldwide and in the United States[2][5].
Where does the Western Rattlesnake live?
It is native to Arizona, California, Colorado, Idaho, Nevada, Oregon, Utah, Washington and Wyoming[3].
What does the Western Rattlesnake eat?
It eats mainly small mammals, and also birds and lizards, and rarely amphibians[13].
When is the Western Rattlesnake active?
Over most of its range it is active from about April to November[15]. Online records peak in April, May and June[17].
What does the CDC say about a rattlesnake bite?
After a bite, the CDC advises seeking emergency medical help right away, and not driving yourself[19].

Facts and sources

  1. Western Rattlesnake is not listed as endangered or threatened under the US Endangered Species Act in USFWS ECOS data (checked 2026-10-30). USFWS ECOS
  2. NatureServe global conservation status rank for Western Rattlesnake: G5 (Secure). NatureServe Explorer
  3. NatureServe lists Western Rattlesnake as native in 9 US states and territories: Arizona, California, Colorado, Idaho, Nevada, Oregon, Utah, Washington, Wyoming. NatureServe Explorer
  4. Western Rattlesnake (Crotalus oreganus) is a reptile in the family Viperidae, order Squamata. NatureServe Explorer
  5. NatureServe national rank in the United States: N5 (Secure). NatureServe Explorer
  6. IUCN Red List category as recorded by NatureServe: Least concern. NatureServe Explorer
  7. NatureServe state ranks for Western Rattlesnake (map and table on this page). NatureServe Explorer
  8. NatureServe estimate of total adult population (global, as a range): 100,000 to >1,000,000 individuals. NatureServe Explorer
  9. US states with the most GBIF observation records of Western Rattlesnake: California, Utah, Washington, Oregon, Nevada. Record counts follow observer effort, not population size. GBIF
  10. Habitat types NatureServe records for Western Rattlesnake: Forest/woodland, Forest edge, Woodland - hardwood, Woodland - conifer, Woodland - mixed, Shrubland/chaparral, Savanna, Grassland/herbaceous, Bare rock/talus/scree, Riparian. NatureServe Explorer
  11. NatureServe notes on habitat for Western Rattlesnake. NatureServe Explorer
  12. Adult food habits recorded by NatureServe: Carnivore. NatureServe Explorer
  13. NatureServe notes on food for Western Rattlesnake. NatureServe Explorer
  14. NatureServe notes on reproduction for Western Rattlesnake. NatureServe Explorer
  15. NatureServe notes on phenology for Western Rattlesnake. NatureServe Explorer
  16. Adult activity patterns recorded by NatureServe: Hibernates/aestivates, Diurnal, Nocturnal, Crepuscular. NatureServe Explorer
  17. GBIF observation records of Western Rattlesnake in the US by month (chart on this page). GBIF
  18. NPSpecies park lists recording Western Rattlesnake as present (list on this page). NPS NPSpecies
  19. Safety guidance from CDC / NIOSH. CDC

Status, range and habitat come from NatureServe Explorer (CC BY 4.0) and USFWS ECOS at the snapshot date. Listings change by federal rule. State lists are where NatureServe records the species, not a promise that you will see it there. Never name a place smaller than a state. GBIF and park records count observations and checklists. They show where and when people report the species, not how many animals live there.

NatureServe. 2026. NatureServe Explorer [web application]. NatureServe, Arlington, Virginia. Available https://explorer.natureserve.org. (Accessed: October 30, 2026). Licensed under CC BY 4.0; SpeciesFacts selected and summarized it.