||Name: Timber Rattler
|Scientific name: Crotalus horridus horridus
|Range: North Central to North Eastern U.S.
|Habitat: forested, rocky hills
|Status: Endangered, illegal to own or keep
| Diet in the wild:rodents, hares, and birds
|Diet in the zoo: mostly rodents diet
|Location in the zoo: Herpeterium
(Not currently on exhibit).
Heads are characteristically wide and spade-shaped, with rounded snouts
Body lengths have been recorded at over 1m (3ft 3in) long
Weight about 4.5 lbs
Ground color is gray or yellowish. 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.
timber rattlers are marked like the adults.
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.
A second lying out period takes place in the autumn before they go down
into the den, but this tends to be a shorter period. In the east,
timber rattlesnakes are the only species that form reasonably large dens,
with over 200 members having been recorded at several locations earlier
Timber rattlesnakes are not a major threat to humans and livestock.
Death due to a bite is unlikely. This snake has a secretive nature and
prefers areas that are unused by humans. They remain quiet, and are often
reluctant to rattle, preferring not to call attention to themselves.
However, timber rattlers will become defensive and bite if disturbed. They
are capable of controlling the injection of venom when biting; up to 80%
of all poisonous snake bites to humans contain no venom.
Special anatomical, physiological
or behavioral adaptations:
The feeding habits of rattlesnakes have been the driving force
behind the evolution of their venom apparatus, and ultimately, the rattle.
The rattle is the structure that sets rattlesnakes apart from all other
snakes. It consists of a series of horny segments, which fit loosely inside
one another. These segments are made of keratin, the same material that
forms fingernails. The rattle has a covering which prevents it from coming
away with the rest of the skin when the snake sheds.
Image courtesy of
Virginia Reptiles and Amphibians
Comments about the timber rattler of the Fort
Due to renovation, This animal is not currently on exhibit.
Due to the absence of the snake, it was not possible to make observations
at this time.
Reptiles and Amphibians
at the Fort Worth Zoo