Eastern Diamondback Rattlesnake

Crotalus adamanteus

Species Description

This rattlesnake is a well known species in the southeast, known for their impressive size, characteristic diamond pattern on their back, and prominent rattle on their tail. They are the largest of all rattlesnake species, with the largest recorded eastern diamondback reaching 99 inches (8.25 ft). However, on average, this species reaches 43-70 inches (~4-6 ft) in length.

Like all snakes, their scale coloration varies throughout the range. In some portions of their range, they have stark black and white coloration, with little brown or yellow in their pattern. In other areas, their scale coloration does not contrast as clearly, resulting in a more "messy" pattern. Although rare, wild specimens have been found with no diamond pattern, striped, and other variations.

Their camouflage is optimized to blend into grasses and vine cover, where they wait to ambush prey. This species is a rabbit-specialist, but will take squirrels, cotton rats, and other prey when the opportunity arises.

Range

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The historic range of the eastern diamondback rattlesnake spans the coastal plain of the southeastern United States from North Carolina to South Florida and west to Mississippi, reaching elevations up to approximately 500 meters. There are indications it may have once extended as far north as southwestern Tennessee and northeastern North Carolina, aligning closely with the historic distribution of the longleaf pine ecosystem.

Presently, the estimated range for eastern diamondbacks covers an area of 200,000-2,500,000 square kilometers, but their habitat and population are declining, leading to contractions in areas such as Louisiana, Mississippi, and both North and South Carolina. Habitat loss is attributed to agricultural expansion, roads, urbanization, human persecution, collection for the skin trade, silviculture, and changes in vegetation due to fire suppression.

Specifically, the species is considered functionally extinct in Louisiana and North Carolina, scarce in South Carolina, with strongholds noted in the northern Florida peninsula, eastern and southern Florida panhandle, and southwestern Georgia. In Louisiana, the last known sighting is from 2016.

In North Carolina, the species is confined to the Lower Coastal Plain south of the Neuse River, with very low population density. South Carolina hosts scattered populations in the lower and middle Coastal Plain and on certain barrier islands.

Georgia's coastal strand and barrier island region constitute significant habitat for eastern diamondbacks, although the species is becoming increasingly rare to find. A notable population center exists in southwestern Georgia, with barrier islands serving as important habitats.

Florida, encompassing approximately half of the species' current range, has seen significant habitat loss, particularly in the peninsula.

In Alabama, eastern diamondbacks are primarily found in the southwestern part of the state, particularly where gopher tortoises occur, and sporadically in other areas such as Dauphin Island and Conecuh National Forest.

In Mississippi, the species is mainly confined to the longleaf pine hills and pine flats regions in the southeastern portion of the state.

Species Status

The eastern diamondback rattlesnake faces numerous challenges across its range, leading to significant population declines. Habitat loss and fragmentation, driven by urbanization, road construction, agriculture, and development, have severely impacted its numbers. Additionally, indiscriminate killing, often driven by fear or misunderstanding, and illegal collection for the skin trade further exacerbate the species' decline.

Presently, the species is not protected by federal regulation or law. Only one state, North Carolina, has listed the species as endangered, despite the species being threatened or endangered in many other states. The U.S. Fish and Wildlife Service is currently conducting a Species Status Assessment to evaluate the species for listing under the Endangered Species Act due to a petition to list the species submitted in 2012.

The species relies on overwintering refugia, particularly above the frostline, to survive harsh weather conditions. In the southern parts of its range, various refugia serve as shelters from fire and extreme weather, including gopher tortoise burrows and other suitable habitats. The loss of gopher tortoise populations and monoculture silvicultural practices have reduced or extirpated populations in many parts of their range, including on conservation lands with poor habitat management. Protecting refugia is critical for the eastern diamondback's long-term survival, especially in areas above the frostline.

Despite changing attitudes towards rattlesnakes and a decrease in activities like "rattlesnake round-ups", collection for the skin trade, and habitat destruction persist as significant threats One rattlesnake roundup in the range of the species has converted to a conservation festival, Whigham Roundup, where only captive snakes are used for education purposes. Another historic rattlesnake roundup, Claxton Rattlesnake Festival, no longer kills snakes publicly; however, they are known to collect wild eastern diamondbacks for the festival, which exposes wild snakes to potentially dangerous pathogens from being in close proximity to captive animals and wild eastern diamondbacks from multiple populations. Eastern diamondbacks are still collected and killed for the Opp Rattlesnake Rodeo in Alabama. The species is also known to be collected, transported, and killed at roundups outside of the range of the species - namely in Texas.

Pathogens pose a risk to eastern diamondback populations, particularly as increasing fragmentation decreases gene flow and redundant populations. Our team has detected two new novel viruses in wild eastern diamondbacks and are currently researching how these viruses may impact populations. Additional pathogens include the fungus Ophidiomyces ophiodiicola, which causes Snake Fungal Disease, and an invasive pentastomid, Raillietiella orientalis, which is becoming more prevalent as intermediate hosts spread the lungworm throughout the range of the species.

Due to the elusive nature of the eastern diamondback and limited population surveys, accurately assessing its current status remains challenging. Nevertheless, continued research efforts using venom to delineate populations, habitat conservation initiatives, and public education campaigns are imperative for its conservation.