Timber Rattlesnakes (Crotalus horridus) are a large, heavy-bodied pit viper. They range throughout much of the eastern half of the United States, but due to human persecution and habitat loss are declining in many regions, including the southern portion of the Blue Ridge Mountains of Northeastern Georgia and Western North Carolina.
Timber Rattlesnakes, like all snakes, are ectotherms (a.k.a. cold blooded). This means they don’t produce their own body heat, but acquire heat through the environment. Gravid females need to keep their body temperature up in order for their young to develop properly during the gestation period. In the southern portion of the Blue Ridge Mountains, Timber Rattlesnakes will seek out rocky outcrops with a south or southwest exposure and little tree cover. These areas get the most sun exposure, allowing the females maximum basking opportunities to help them maintain a high body temperature. Boulders and rock crevices provide refuge from predators or inclement weather. We refer to these sites as gestation sites. Female Timber Rattlesnakes will typically arrive at a gestation site around May or June, and remain there until their young are born around August or September. During the gestation period, they do not attempt to forage but must rely on fat storage from previous years for all of their energy needs. Because of the high energy demands of developing young, Timber Rattlesnakes in the Blue Ridge are only able to give birth every 3 years or more.
Timber Rattlesnakes share these rocky outcrops with a number of other species. Gestating Copperheads (Agkistrodon contortrix) can be found basking right next to Timber Rattlesnakes all summer long and will share the same rocks or crevices. Other species commonly encountered are Garter Snakes (Thamnophis sirtalis), Ringneck Snakes (Diadophis punctatus), Smooth Earth Snakes (Virginia valeriae), and Eastern Milk Snakes (Lampropeltis triangulum triangulum). Most of these other species utilize the outcrops during the spring but move into other habitats during the heat of the summer. Due to the importance of these sites to Timber Rattlesnakes and other species, it is essential to be able to identify and protect them.
Last year at The Orianne Society we began surveying for these gestation sites throughout the Blue Ridge region of northeastern Georgia and we were able to identify a large number of locations that had gravid females. This summer we are going to continue these surveys as well as extend them into western North Carolina. We are going to use the data collected from these surveys to develop computer models that allow us to identify suitable gestation habitat that we may have missed during our on-the-ground surveys. These models will be essential in helping to protect gestation sites from development as well as helping us set up future monitoring efforts to determine if there may be population declines.