Crotalus atrox
Western Diamond-backed Rattlesnake

Venomous. Mottled brown, tan, and black with large, roughly diamond-shaped middorsal blotches. Blotches thinly etched with white except toward tail. Heat-sensing pits. Eyes elliptical and between light, diagonal stripes. Coon tail with rattle. Species account on iNaturalist
Arkansas Game & Fish Commission
Species of Greatest Conservation Need

Arkansas Herpetological Atlas 2019

This species is represented by 58 records from 11 sources: 25 museum (), 9 literature (), 0 research (), and 18 observation (), with 6 additional Trauth et al. (2004) locality points remaining unsourced (). It has been museum vouchered for 9 of 75 counties (), with 8 additional counties having other forms of reported occurrence (). Years of collection range from 1927 to present.

This species has a spotty distribution in the Ouachita Mountains, mountainous portions of the Arkansas Valley, and southern Boston Mountains. It likely has a much wider distribution through the central Ouachita Mountains, but records are lacking. No museum vouchers exist north of the Arkansas River, though historical literature and contemporary observation reports clearly establish its presence in the southern Boston Mountains. Notably, a large female specimen from the vicinity of Mountainburg, Crawford/Franklin County, was radio-tracked by researchers from 2003-2005 (B. Birchfield, S. J. Beaupre, and K. G. Roberts, unpublished data), yet extensive surveys failed to locate additional individuals. A highly questionable record from White County (SDNHM 6550 from 1931) almost assuredly belongs to a set of 10 specimens collected in northern Saline County (Perkins, 1934). A Trauth et al. (2004) record from Miller County is based on a known transplanted specimen (K. J. Irwin, pers. comm.). From the historical literature, there are purportedly firsthand accounts of occurrences from northeast Arkansas, stretching even into Butler County, Missouri (Perkins, 1934), but the degree of reliability for such extraordinary claims is difficult to gauge.