Dr. Khan's
Allergy and Immunology Information Site

Timber (Canebrake) Rattlesnake - Crotalus horridus

The Timber Rattlesnake is our second largest venomous snake here in the southeast.  This species occurs over most of the eastern half of the United States but its numbers are declining in many areas, especially in the northern parts of its range.  In Florida, it occurs only in the northern portions of the state, but it lives throughout Georgia and South Carolina.  Relatively recent taxonomic revisions based on genetic analysis have eliminated subspecies designations for all populations of Timber Rattlesnake, although some genetic difference does exist between northern, western and southern populations (see Clark, A.M., et al. 2003).  Previously, the southern / southeastern populations were classified as Crotalus horridus atricaudatus, the Canebrake Rattlesnake.

 

 

Southeastern populations, although now designated with other geographic populations as Crotalus horridus, do possess distinct characteristics when compared to their northern counterparts.  For example, northern Timbers congregate in dens during the winter to hibernate.  The same dens are used by successive rattlesnake generations so many of these hibernacula have been in use for hundreds and possibly thousands of years.  This behavior has probably contributed to the decline of northern populations because the snakes were easily located and killed / collected.  However, southeastern Timbers do not congregate in large groups to overwinter, and they are still common where suitable habitat exists.

 

 

The southeastern Timber Rattlesnake prefers wooded areas including pine and hardwood forests.  Low-lying forests that border water (like swamps) are favored.  Forested areas where switchcane (Arundinaria gigantean) grows are also preferred habitats, hence the name "Canebrake" rattlesnake.  In parts of their range, southeastern Timber Rattlesnakes live in the same habitats as their larger relative, the Eastern Diamondback Rattlesnake.  Like the Eastern Diamondback, Timbers prey mostly upon mammals and birds.  Small mammals like mice, rats, shrews and voles make up the bulk of their diet.  Larger adults will take bigger prey such as squirrels and rabbits (see Clark, R.W. 2002 for further information on diet).  The tendency of Timbers to prey on smaller mammals probably allows them to successfully coexist in habitats with Eastern Diamondbacks which more commonly take larger animals like rabbits (S.H. Bennett, personal communication).  This preference in prey size is reflected in the relative head sizes of Timber and Diamondback Rattlesnakes, with Timbers possessing smaller heads in proportion to their bodies as compared to Eastern Diamondbacks.


Southeastern examples of Crotalus horridus have a variable background coloration which can vary from brown, beige, grey, salmon, to pink (or any combination thereof).  The typical pattern consists of dark colored chevrons that begin at the neck and cover most of the body with the exception of the tail, which is usually solid black.  Like other rattlesnakes, the Timber possesses a rattle at the end of its tail which it vibrates to produce a buzzing sound as a warning when agitated.  A bite from this species is a medical emergency.  Several fatalities from its bite are on record.  A 1994 study examining venom characteristics of this species with respect to geographic location showed some populations in South Carolina and Georgia possess a particular toxin which gives these localities of Timber rattlesnakes especially potent venom (Glenn, J.L., et al. 1994).  This toxin, called "canebrake toxin", conveys neurotoxic properties to venom.  Timber populations frequently possess hemotoxic / tissue-destructive properties, and severe muscle damage is characteristic of envenomation by this species (Carroll, R.R, et al. 1997).  These snakes from our region (southeastern / coastal SC and GA) may possess venom with significant neurotoxic and hemotoxic / tissue-destructive abilities.

 

 

 

 

Clearly, a bite from a Timber Rattlesnake is an extremely unfortunate and potentially devastating event.  Those of us who live in this species’ range should take precautions to avoid encounters which may produce a bite.  For example, keep your property free of debris like leaves and limbs which can provide hiding places for snakes.  Their pattern and coloration make them hard to see when they are lying amongst vegetation.  Also, keep outdoor trash and pet food containers secured so that small animals are not attracted to your property.  Snakes are drawn to areas frequented by small prey animals like mice and rats.  Rattlesnakes are most active in the spring and fall seasons, so be especially observant when outdoors during these times of year.  Visiting a zoo or reptile exhibit / presentation is a good place to learn more about venomous snakes and become familiar with their appearance.  If you do see one of these snakes, it is best to leave it alone.  If the snake is in your yard and you want it removed, it is better to telephone animal control for advice than trying to manage the snake yourself.  A good many bites occur when people are trying to kill or capture the snakes.  My comments about first aid and treatment mentioned on the Eastern Diamondback page apply to Timber Rattlers as well.  You can read more about these here:  things you shouldn't do in the event of a venomous snake bite.

 

As always, I welcome questions about these snakes or any other subjects on this web site.  Please feel free to e-mail me with questions or comments.

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