Eastern Diamond-backed Rattlesnake Conservation

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An Eastern Diamond-backed Rattlesnake observed on a winter tortoise burrow survey in southeastern Georgia – Houston Chandler

I have worked with many fascinating reptile and amphibian species over the years, but few experiences compare to interacting with large rattlesnakes. They are impressive and charismatic animals that have a reputation not at all deserved. Often portrayed as vicious and aggressive, most rattlesnakes that I have observed in the southeast will flee at the first opportunity and some even decline to rattle, despite being disturbed by pesky researchers. Like Cottonmouths, their reputation is greatly exaggerated and is based on a poor understanding of animal behavior. On more than one occasion I have been startled by how close my feet have been to large rattlesnakes without the snake giving any indication of its presence. During one of my first indigo snake surveys, I nearly stepped on a large Eastern Diamond-backed Rattlesnake (Crotalus adamanteus; EDB for short) before I realized it was there. The snake ultimately retreated down a nearby tortoise burrow rather than be exposed to a potential predator (me).

Few animals in the southeast are as impressive as a full grown EDB. One of the largest, both in terms of weight and length, snakes native to the U.S., EDBs were historically found in portions of seven states (Florida, Georgia, South Carolina, North Carolina, Alabama, Mississippi, and Louisiana). Today, EDBs are thought to be extirpated from Louisiana and rare or extirpated in many parts of their former range in Mississippi and Alabama. Across this relatively broad range, EDBs can be found in a variety of habitats, including swamp forests, xeric hammocks, tropical hammocks, oak scrubs, temperate hardwood forests, salt marshes and coastal dunes. However, they are most often associated with open canopy pine savannas, particularly ones occupied by Gopher Tortoise populations. This highlights the importance of habitat features (e.g., tortoise burrows) that provide refugia from potentially lethal winter temperatures.

EDBs, like many species in the southeast, are generally thought to be declining across their range, in addition to the range contractions highlighted above. They face the myriad of threats that most species experience, including habitat loss and degradation, habitat fragmentation (roads are a particular problem), climate change, introduced species, and disease. However, rattlesnakes have also suffered extensively from direct and targeted human persecution, both in the form of indiscriminate killing and the collection of snakes for rattlesnake roundups that were historically widespread in the southeast. These issues are further exacerbated by the dubious legal status that the species receives in some parts of its range. For example, in Georgia, all venomous snakes receive no legal protection even when they occur on state-owned, protected properties. This means that some populations in otherwise well-managed and protected landscapes may still experience the negative effects of human persecution. EDBs are currently a candidate for federal listing under the U.S. Endangered Species Act. The U.S. Fish and Wildlife Service is currently working on gathering data from across the species’ range to inform a Species Status Assessment and ultimately a listing decision (which is sure to be contentious either way).

An adult EDB basking in the sun on a cool winter day – Houston Chandler

Over the years, we have completed several projects either focused on or incorporating EDBs. The longest has been an assessment of EDB site occupancy and detection probability using winter tortoise burrow surveys (Bauder et al. 2017). These data are collected as part of our annual indigo snake monitoring in southeastern Georgia and highlight how projects can be designed to collect data on multiple species with a single survey type. In addition to this long-term monitoring project, we also sampled several EDBs as part of our large-scale assessment of Snake Fungal Disease in Georgia (Haynes et al. 2020), and we have worked with state agencies to create state-specific models mapping suitable habitat. On the education side of things, we have participated in the Claxton Rattlesnake and Wildlife Festival for several years after it transitioned away from a roundup to a snake-friendly event. Suffice to say EDBs have long been one of our focal species.

Houston Chandler (left) and Ben Stegenga (right) swabbing an EDB for Snake Fungal Disease – David Hutto

To inform the upcoming Species Status Assessment and provide data that the Fish and Wildlife Service will use to inform the listing decision, The Orianne Society is currently working on a two-year EDB project. This project is aimed at filling some of the existing data gaps in southeastern Georgia using multiple techniques, including targeted survey efforts, additional mark-recapture surveys at The Orianne Society’s Longleaf Stewardship Center where EDBs have been marked for many years, and solicitation of records from the public (keep an eye out for information on how to submit records in the near future). In addition to these data gathering efforts, we will use the collected data as well as data from partners across the range to build a range-wide habitat suitability model, following the methodology we recently used for indigo snakes (Chandler et al. 2022). It is important to zoom out and take this range-wide approach when considering the status of a species overall.

This project is an exciting opportunity to work with one of the Southeast’s most charismatic species and directly contribute to ongoing conservation work. Stay tuned for additional updates and opportunities to contribute data to this project!

 

Literature Cited

Bauder, J. M., D. J. Stevenson, C. S. Sutherland, and C. L. Jenkins. 2017. Occupancy of potential overwintering habitat on protected lands by two imperiled snake species in the Coastal Plain of the southeastern United States. Journal of Herpetology 51:73–88.

Chandler, H. C., C. L. Jenkins, and J. M. Bauder. 2022. Accounting for geographic variation in species-habitat associations during habitat suitability modeling. Ecological Applications:e2504.

Haynes, E., H. C. Chandler, B. S. Stegenga, L. Adamovicz, E. Ospina, D. Zerpa‑catanho, D. J. Stevenson, and M. C. Allender. 2020. Ophidiomycosis surveillance of snakes in Georgia, USA reveals new host species and taxonomic associations with disease. Scientific Reports 10:10870.