Over this are a number of velvety black chevrons or crossbars. The background color becomes darker towards the tail and some forms of the timber rattlesnake are heavily suffused with black, making the markings difficult to see. Rattle is a series of horny shells fitted loosely inside one another and are made of keratin. Tails of rattlesnakes are relatively short, perhaps to make it easier to vibrate its rattle.
Males are heavier bodied than females.
Juvenile timber rattlers are marked like the adults. Image courtesy of West Virginia Reptiles and Amphibians Timber rattlesnakes hibernate in den sites, and often spend several days in the spring basking near the entrance before they disperse. This is known as lying out . They will stay close to the den site until temperatures become warm. Pregnant females will usually remain around denning sites.