Habitat and Geography

Crotalus horridus can be found in almost every state across the eastern half of the United States.  From eastern Texas all the way north to southern New Hampshire, this creature has a tremendous range.  However, populations within this vast range are scant and are continuing to diminish at rapid rates due to habitat encroachment. Though the majority of the C. horridus species is located in the southeastern regions of the U.S., this rattlesnake hits close to home for those individuals living in Minnesota, Iowa, and Wisconsin, especially along the Mississippi River.  Another common rattlesnake found in this particular area is the Eastern Massasauga Rattlesnake. The timber rattlesnake is also present in many northeastern states, including Ohio and Pennsylvania and all the way north into New Hampshire and parts of New Jersey.  Below is a map of the US displaying the numerous areas where you can find C. horridus :

                 Many environmental and developmental factors influence the types of habitats that C. horridus resides in.  Some of these factors include gravidity (pregnancy)  of the females, the time or season of the year, and the presence of other organisms within the area that aid in their survival, whether it be prey items or trees that provide shade and shelter.  The main determinant in finding a suitable habitat is one that can support ectothermic populations of terrestrial animals, like C. horridus.  Since C. horridus is "cold-blooded" or ectothermic, it does not have the ability to regulate its own body temperature.  Therefore, it must find a home that provides the appropriate temperatures necessary to survive.  For the most part, timber rattlesnakes choose their home based on the time of year and the current weather. 
                 During the summer, when the weather is obviously much warmer, timber rattlesnakes prefer to find homes in moist, lowland forests and hilly woodlands or thickets, typically near accessible water sources, such as rivers, lakes, ponds, streams and swamps.  These forested habitats are usually more than 50% canopy and over 75% vegetative ground cover.  This vegetative ground cover is important in keeping the rattlesnakes cool by providing shelter and refuge from the sun on hot summer days and includes eroding root systems, shrubs, grasses, decaying logs, tree stumps, branches, and leaf litter that has fallen from the deciduous trees surrounding them.  The trees themselves provide a large percentage of the shade needed to keep their body temperatures at a low level in the hot heat.  Though these barriers from the sun are necessary when the weather is too warm, many of the snakes actually take advantage of the nice weather and spend a lot of time basking in sunny open areas surrounded by their typical forested habitat.  This combination of forest and open field lands ensures the fact that they can stay warm in the sun while still being able to keep cool under the shade of a tree.  In fact, during the summer, gravid females prefer to remain in open canopy bluff-prairies in order to keep their body temperatures high, but if they become too overheated, they do have the option to resort back to the various structures that provide shade, such as brush, trees and rock shelves.  Generally, gravid females prefer 25% canopy cover and equal amounts of vegetation. Adult males and non-gravid females, however, prefer to be cooler most of the time, hence they stay in areas closer to forest and woodland edges.
Though the majority of timber rattlesnakes reside in regions of lower altitude, several populations have been found living along rocky ridges and upland woods in mountainous areas. In fact, they have been known to occupy elevations of up to 6000 feet in upland hardwood, mixed pine-hardwood, and hemlock forests.  These hardwood forests consist of trees such as the Sugar (Hard) Maple, Eastern Cottonwood, and the Silver (Soft) Maple.  All are important to the timber rattlesnake's habit because they provide enough foliage for proper shading.   Like that on ground level, the forest and open area buffer system still proves to be beneficial for these organisms even in these higher altitude habitats.  Instead of open sunny fields, however, timber rattlers are found along sunny, rocky outcroppings, slopes, ledges, and road cuts, as well as steep bluffs.  As long as they still have access to both sun and shade in order to moderate their body temperature, altitude isn't a large factor in determining habitat.
                 When winter begins to set in and temperatures start to decrease, timber rattlesnakes will  return to their same hibernation den, year after year, much like how bears do to keep warm during the cold winter months.  Typically, timber rattlesnakes choose to hibernate in dens that run along mountainous terrain, but many will settle in dens located in pineland habitats near cedar swamps and stream banks.  Along these rocky ridges, timber rattlesnakes will seek refuge below the frost line, such as large cracks in rock outcroppings, fissures in a ledge, fallen rock partially covered by soil, underground cavities, and crevices of dark caves.  Some will even travel far into the sides of steep bluffs or settle comfortably in the burrows of other animals.  Either way, these well sheltered areas are necessary for the rattlesnake to stay sufficiently warm and protected from the snow and bitter cold temperatures of winter.  On warm days during hibernation, timber rattlesnakes may emerge temporarily to bask in the sun, but will then quickly return as temperatures begin to drop and nighttime sets in. Lastly, timber rattlesnakes tend to hibernate in communal dens that provide a home for dozens of other related individuals, as well as many other species of snakes in general.  As spring nears, and temperatures begin to rise once more, snakes of all kinds will start to emerge from their dens and travel to their usual summer habitats.  Generally, timber rattlesnakes are the last to emerge from their dens in the spring and the first to retreat to them in the fall.





Back to Home Page
To learn more about the Adaptations of this organism, click here