The western diamondback rattlesnake is the most wide-ranging rattlesnake in the southwestern United States and one of the most consequential venomous snakes in North America, responsible for the greatest number of snakebites in the country and a substantial share of fatal envenomations [Greene et al. 2021]. Beyond its medical reputation, Crotalus atrox is an abundant, ecologically important rodent predator across deserts, grasslands, and rocky scrub from central Arkansas to southeastern California and deep into north-central Mexico [IUCN 2007]. This profile examines its biology, its standing as a species of Least Concern, and the harvest and persecution pressures — including the long-running practice of "rattlesnake roundups" — that complicate an otherwise secure conservation picture.
Biology and Identification
Adult western diamondbacks typically reach about 120 cm in total length; individuals exceeding 150 cm are uncommon, and the largest verified specimens approach 213 cm. Males grow larger than females after maturity, with medium-sized animals weighing roughly 1.2–2.7 kg [Beaupre 2005]. The species is the second-largest rattlesnake by body size, after the closely related eastern diamondback (Crotalus adamanteus).
The common name derives from a dorsal series of brown to umber blotches that grade into distinct hexagons and diamonds along the back, set against a ground color ranging from gray and khaki to pinkish or brick red. A pale-bordered, diagonal postocular stripe runs from the eye, and the tail bears alternating black and white-to-gray bands — the so-called "coon tail" — immediately above the rattle, a reliable field mark separating it from sympatric rattlesnakes.
The rattle is a sequence of loosely interlocking keratin segments at the tail tip; a new segment is added at each skin shed, and rapid muscular oscillation produces the characteristic buzzing warning. Like all pit vipers, the western diamondback possesses paired heat-sensing pit organs between the eye and nostril. These organs detect infrared radiation through temperature-sensitive nerve fibers, allowing the snake to locate and strike warm-bodied prey in darkness; the molecular basis of this infrared sense is the ion channel TRPA1, the most heat-sensitive vertebrate ion channel characterized to date [Gracheva et al. 2010; Geng & Gracheva 2010].
The venom is primarily hemotoxic, rich in zinc-dependent snake-venom metalloproteinases that damage blood vessels and tissue, alongside cytotoxic and myotoxic components [Bekešová et al. 2024]. Diet shifts with age: juveniles take lizards more often, while adults specialize heavily on small mammals. A classic dietary study in Texas found that small mammals — including woodrats, kangaroo rats, pocket gophers, ground squirrels, mice, and rabbits — made up the overwhelming majority of prey by mass [Beavers 1976]. In this role the western diamondback functions as a significant regulator of rodent populations across its range [Nowak et al. 2008].
Habitat and Range
The western diamondback occupies one of the broadest ranges of any North American rattlesnake, extending from central Arkansas and Oklahoma west through Texas, New Mexico, and Arizona to southeastern California, with records in extreme southern Kansas and southeastern Nevada. In Mexico it ranges through Coahuila, Chihuahua, Sonora, Nuevo León, Baja California, Sinaloa, Durango, Zacatecas, San Luis Potosí, and as far south as Hidalgo and Querétaro [IUCN 2007].
It is an ecological generalist, occurring across flat coastal plains, rocky canyons and hillsides, desert and creosote flats, mesquite grassland, desert scrub, and into pine-oak woodland. The species tolerates human-modified landscapes and persists in semi-urban settings around cities such as Phoenix and Tucson, which contributes to frequent human encounters. It is largely inactive during the coldest months, sheltering in dens, burrows, and rock crevices [IUCN 2007].
In accordance with NRWL sensitive-species policy, specific site locations, corridor routes, and seasonal movement details are not disclosed in this article.
Conservation Status
The western diamondback rattlesnake is listed as Least Concern on the IUCN Red List, assessed in 2007, on the basis of its very wide distribution, presumed large population, occurrence in numerous protected areas, and tolerance of habitat modification; the global population trend was reported as stable at assessment [IUCN 2007]. The species is not listed on any CITES appendix, so its international trade is not regulated under the Convention [CITES 2023].
This secure global status does not mean the species is free of pressure. Large numbers are removed from wild populations each year through commercial harvest, and localized declines have been documented in heavily collected areas [Fitzgerald & Painter 2000]. The Least Concern listing reflects range-wide abundance rather than the absence of regional impacts, and population data for many parts of the range remain limited.
Threats
Commercial harvest and roundups. The most distinctive conservation issue for Crotalus atrox is sustained commercial collection, much of it associated with annual "rattlesnake roundups" in Texas, Oklahoma, and neighboring states. These events gather, sell, and slaughter snakes by the thousand for meat, skins, and entertainment. Long-term analyses of the rattlesnake trade documented large and persistent harvest volumes and raised concerns about localized population effects and the lack of monitoring or harvest regulation across most of the range [Fitzgerald & Painter 2000]. A widely cited case study of the Sweetwater, Texas roundup examined the conservation and ethical dimensions of an event that kills large numbers of western diamondbacks each year [Weir 1992].
Gassing of dens. A common collection method involves pumping gasoline or its fumes into underground dens and burrows to drive snakes out. This practice degrades shared shelter sites and can harm the many non-target species — other reptiles, amphibians, invertebrates, and small mammals — that depend on the same refuges [Fitzgerald & Painter 2000].
Persecution and road mortality. As a venomous species often encountered near human settlement, the western diamondback is frequently killed on sight, and road traffic adds further mortality where roads bisect habitat [IUCN 2007].
Habitat conversion. Although the species tolerates disturbance better than many snakes, large-scale conversion of grassland and desert scrub to agriculture and development removes denning and foraging habitat at local scales [IUCN 2007].
What Is Being Done
Research and monitoring. Peer-reviewed work on the rattlesnake trade has provided the data foundation for evaluating harvest pressure and for advocating monitoring of commercial collection [Fitzgerald & Painter 2000]. Long-term ecological studies of growth, energetics, and foraging continue to refine understanding of how Crotalus atrox populations respond to environmental variation and resource availability [Beaupre 2005].
Reform of roundup practices. Several traditional roundups have transitioned toward "no-kill" or educational formats that emphasize live exhibition, public outreach, and conservation messaging rather than slaughter, and regulatory attention has focused on restricting the gassing of dens because of its broad impacts on non-target wildlife [Fitzgerald & Painter 2000].
Protected areas. The species occurs within numerous national parks, wildlife refuges, and other protected lands across its range, where collection is prohibited and habitat is conserved [IUCN 2007].
Public-health and coexistence efforts. State wildlife and public-health agencies, including the U.S. Fish & Wildlife Service, provide species information and guidance on safe coexistence and snakebite prevention, helping to reduce both human risk and unnecessary killing of snakes [USFWS 2023].
How Readers Can Help
Practice safe coexistence. Most bites occur when snakes are handled or harassed. Give rattlesnakes space, wear appropriate footwear in snake habitat, and allow snakes to move away rather than attempting to kill or capture them [USFWS 2023].
Support no-kill events and oppose gassing. Where roundups occur, support organizers and policies that adopt no-kill, educational formats and that prohibit the gassing of dens, which harms a wide range of native wildlife [Fitzgerald & Painter 2000].
Contribute to citizen science. Photograph and log rattlesnake observations through platforms such as iNaturalist. Verified occurrence records improve range maps and inform future assessments.
Share accurate information. Counter fear-driven misperceptions with science-based information about the ecological value of rattlesnakes as rodent predators, and about the small absolute number of snakebite fatalities relative to the volume of human–snake encounters [Greene et al. 2021].
References
[Beaupre 2005] Beaupre, S.J. (2005). Ecological modeling of female western diamondback rattlesnakes: effects of food supplementation on the physiological ecology of Crotalus atrox. Oecologia, 145(1), 109–119. https://doi.org/10.1007/s00442-005-0056-x
[Beavers 1976] Beavers, R.A. (1976). Food habits of the western diamondback rattlesnake, Crotalus atrox, in Texas (Viperidae). The Southwestern Naturalist, 20(4), 503–515. https://doi.org/10.2307/3669868
[Bekešová et al. 2024] Bekešová, B., Petrilla, V., Polláková, M., Andrejčáková, Z., Vlčková, R., Dyba, B., Sopková, D., Petrillová, M., Petrovová, E. & Legáth, J. (2024). A comparative analysis of the cytotoxic and vascular activity effects of western diamondback rattlesnake (Crotalus atrox) and eastern diamondback rattlesnake (Crotalus adamanteus) venoms using a chick embryo model. Animals, 14(11), 1634. https://doi.org/10.3390/ani14111634
[CITES 2023] CITES. (2023). Appendices I, II and III. Convention on International Trade in Endangered Species of Wild Fauna and Flora. Crotalus atrox is not listed on any CITES appendix. https://cites.org/eng/app/appendices.php
[Fitzgerald & Painter 2000] Fitzgerald, L.A. & Painter, C.W. (2000). Rattlesnake commercialization: long-term trends, issues, and implications for conservation. Wildlife Society Bulletin, 28(1), 235–253. https://agrilife.org/fitzgerald/rattlesnake-commercialization/
[Geng & Gracheva 2010] Geng, J. & Gracheva, E.O. (2010). Infrared snake eyes: TRPA1 and the thermal sensitivity of the snake pit organ. Science Signaling, 3(127), pe22. https://doi.org/10.1126/scisignal.3127pe22
[Gracheva et al. 2010] Gracheva, E.O., Ingolia, N.T., Kelly, Y.M., Cordero-Morales, J.F., Hollopeter, G., Chesler, A.T., Sánchez, E.E., Pérez, J.C., Weissman, J.S. & Julius, D. (2010). Molecular basis of infrared detection by snakes. Nature, 464(7291), 1006–1011. https://doi.org/10.1038/nature08943
[Greene et al. 2021] Greene, S.C., Folt, J., Wyatt, K. & Brandehoff, N.P. (2021). Epidemiology of fatal snakebites in the United States 1989–2018. American Journal of Emergency Medicine, 45, 309–316. https://doi.org/10.1016/j.ajem.2020.08.083
[IUCN 2007] Frost, D.R., Hammerson, G.A. & Santos-Barrera, G. (2007). Crotalus atrox. The IUCN Red List of Threatened Species 2007: e.T64311A12763519. https://dx.doi.org/10.2305/IUCN.UK.2007.RLTS.T64311A12763519.en
[Nowak et al. 2008] Nowak, E.M., Theimer, T.C. & Schuett, G.W. (2008). Functional and numerical responses of predators: where do vipers fit in the traditional paradigms? Biological Reviews, 83(4), 601–620. https://doi.org/10.1111/j.1469-185X.2008.00056.x
[USFWS 2023] U.S. Fish & Wildlife Service. (2023). Western diamondback rattlesnake (Crotalus atrox) — species profile. https://www.fws.gov/species/western-diamondback-rattlesnake-crotalus-atrox
[Weir 1992] Weir, J. (1992). The Sweetwater rattlesnake round-up: a case study in environmental ethics. Conservation Biology, 6(1), 116–127. https://doi.org/10.1046/j.1523-1739.1992.610116.x