Western diamondback rattlesnake (Crotalus atrox)
The western diamondback rattlesnake is a venomous pit viper in the family Viperidae. GBIF holds 5,763 licensed U.S. records of it; it reaches our listing threshold in 7 states, most of all Texas (2,667), Arizona (1,790) and New Mexico (684). Its observation records peak in August.
The western diamondback rattlesnake (Crotalus atrox) or western diamond-backed rattlesnake, is a rattlesnake species and member of the viper family, found in the southwestern United States and Mexico. Like all other rattlesnakes and all other vipers, it is venomous. It is likely responsible for the majority of snakebite fatalities in northern Mexico and the greatest number of snakebites in the U.S. No subspecies are currently recognized.
From Wikipedia: Western diamondback rattlesnake, text under CC BY-SA 4.0.
Is the western diamondback rattlesnake poisonous or venomous?
Yes. The western diamondback rattlesnake is a pit viper (family Viperidae), like every rattlesnake, copperhead and cottonmouth in the U.S. Its bite needs emergency care: call 911 and keep the bitten limb still. Antivenom is given in hospital.
Snakes often mistaken for it
Species commonly confused with rattlesnakes and recorded in the same states: gopher snake (recorded in 6 of its 7 states), Great Plains rat snake (recorded in 4 of its 7 states), plains hog-nosed snake (recorded in 4 of its 7 states) and eastern hog-nosed snake (recorded in 3 of its 7 states).
Which states have the western diamondback rattlesnake?
Records are spread over 7 states; the top three, Texas, Arizona and New Mexico, hold 89% of them. It is the most recorded snake of all in Texas and Arizona.
Records filed under this name in Kansas are not counted: there the name stands for another species, or the record lies outside this species’ range.
| # | State | Records | Share of state snakes | Rank in state |
|---|---|---|---|---|
| 1 | Texas | 2,667 | 6.5% | 1st of 86 |
| 2 | Arizona | 1,790 | 8.7% | 1st of 60 |
| 3 | New Mexico | 684 | 10.6% | 2nd of 56 |
| 4 | Oklahoma | 417 | 3.1% | 12th of 50 |
| 5 | California | 169 | 0.2% | 34th of 46 |
| 6 | Nevada | 17 | 0.4% | 23rd of 27 |
| 7 | Arkansas | 8 | 0.2% | 30th of 36 |
When is the western diamondback rattlesnake seen?
Across the U.S., observation records of the western diamondback rattlesnake run mostly March through September, peaking in August with 25% 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 (Arizona and Texas) and latest in May (New Mexico). The most common peak month is August, shared by Arizona and New Mexico.
| State | Main season | Peak month | Observation records |
|---|---|---|---|
| Arizona | March through September | August | 852 |
| Texas | March through October | April | 730 |
| New Mexico | May through October | August | 349 |
Where the western diamondback rattlesnake is recorded in each state
Texas
Texas holds 2,667 licensed records, the most recorded of 86 snakes listed there. Its observation records in Texas run mostly March through October, peaking in April; most licensed records come from Brewster County, El Paso County and Kent County. Next come Jeff Davis County (76) and Travis County (74).
Arizona
Arizona holds 1,790 licensed records, the most recorded of 60 snakes listed there. Its observation records in Arizona run mostly March through September, peaking in August; most licensed records come from Pima County, Cochise County and Maricopa County. Next come Pinal County (146) and Yavapai County (130).
New Mexico
New Mexico holds 684 licensed records, the 2nd most recorded of 56 snakes listed there. Its observation records in New Mexico run mostly May through October, peaking in August; most licensed records come from Hidalgo County, Doña Ana County and Eddy County. Next come Luna County (37) and Otero County (34).
Oklahoma
Oklahoma holds 417 licensed records, the 12th most recorded of 50 snakes listed there. Most of its licensed records in Oklahoma come from Comanche County, Blaine County and Atoka County. Next come Murray County (10) and Greer County (8).
California
California holds 169 licensed records, the 34th most recorded of 46 snakes listed there. Most of its licensed records in California come from Riverside County, Imperial County and San Bernardino County. Next come Fresno County (1).
Top counties in the U.S.
| # | County | State | Records | Share of U.S. |
|---|---|---|---|---|
| 1 | Pima County | Arizona | 592 | 10.3% |
| 2 | Cochise County | Arizona | 430 | 7.5% |
| 3 | Comanche County | Oklahoma | 294 | 5.1% |
| 4 | Maricopa County | Arizona | 286 | 5.0% |
| 5 | Hidalgo County | New Mexico | 260 | 4.5% |
| 6 | Brewster County | Texas | 200 | 3.5% |
| 7 | Pinal County | Arizona | 146 | 2.5% |
| 8 | Yavapai County | Arizona | 130 | 2.3% |
| 9 | Doña Ana County | New Mexico | 120 | 2.1% |
| 10 | El Paso County | Texas | 114 | 2.0% |
| 11 | Riverside County | California | 95 | 1.6% |
| 12 | Kent County | Texas | 83 | 1.4% |
| 13 | Jeff Davis County | Texas | 76 | 1.3% |
| 14 | Travis County | Texas | 74 | 1.3% |
| 15 | Santa Cruz County | Arizona | 69 | 1.2% |
How recent are the western diamondback rattlesnake records?
The western diamondback rattlesnake record leans on older material: only 31% of dated U.S. records come from 2017–2026, and the median record is from 1995. The oldest dated record is from 1855; the busiest year was 2024, with 278 records.
| Decade | Records | Share |
|---|---|---|
| 1850s | 3 | 0.1% |
| 1860s | 1 | 0.0% |
| 1890s | 11 | 0.2% |
| 1900s | 17 | 0.3% |
| 1910s | 34 | 0.6% |
| 1920s | 101 | 1.8% |
| 1930s | 320 | 5.8% |
| 1940s | 407 | 7.4% |
| 1950s | 348 | 6.3% |
| 1960s | 648 | 11.8% |
| 1970s | 477 | 8.7% |
| 1980s | 270 | 4.9% |
| 1990s | 229 | 4.2% |
| 2000s | 394 | 7.2% |
| 2010s | 953 | 17.3% |
| 2020s | 1,288 | 23.4% |
Species recorded in the same counties
Of the 54 counties where the western diamondback rattlesnake is most recorded, 43 are also top counties for the gopher snake, more than for any other snake. None of its closest neighbors is venomous.
| Species | Shared counties |
|---|---|
| Gopher snake | 43 |
| Glossy snake | 37 |
| Long-nosed snake | 37 |
| Coachwhip | 36 |
| Ring-necked snake | 31 |
| Western ground snake | 31 |
| Striped whipsnake | 29 |
| Blackneck garter snake | 27 |
Related species in the U.S.
Other species of the genus Crotalus with profiles here: Western rattlesnake, Prairie rattlesnake, Sidewinder, Timber rattlesnake, Mohave rattlesnake, Red diamond rattlesnake, Black-tailed rattlesnake and Eastern diamondback rattlesnake.
GBIF records read 2026-09-29. Listed: any license. Counted: CC0/CC BY only. How we count.