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(Above) Eastern Diamondback Rattlesnake (Crotalus
adamanteus).
Liberty Co., FL
The information below is taken from the brochure written
for the Gopher Tortoise Council, about the Eastern Diamondback Rattlesnake, by Karl Studenroth.
Eastern Diamondback Rattlesnake
A Species In Decline
Gopher tortoise burrows are used by many forms of wildlife.
Each year critical tortoise habitat is lost as more and more upland areas are developed. As tortoise habitat disappears so
do many tortoise "burrow commensals" (other animals that depend on tortoise burrows for shelter and survival). One of these
species is a large, handsome snake known in story and legend throughout the Southeast -- the eastern diamondback rattlesnake
(Crotalus adamanteus).
The diamondback, along with many other upland snake species,
is declining over most of its range. This page was developed to provide information about the decline of this magnificent
creature and what can be done to help conserve the diamondback, the gopher tortoise and other upland species.
Ancient History
The ancestors of the eastern diamondback rattlesnake were
part of an ancient dry-habitat fauna that stretched from Florida to the southwestern United States. This fauna included such
forms as the scrub jay, gopher tortoise and burrowing owl - species familiar to modern Floridians. Rattlesnakes, which are
in the Viper family of snakes (Viperidae), probably originated in Mexico and the Southwest about 8 million years ago. They
have since spread throughout most of the continental U.S., parts of Canada, and Central and South America. In Florida, fossil
remains indicate that the diamondback has existed in the area for at least 2 million years.
Size
The eastern diamondback is the largest rattlesnake in
the world. Although outlandish stories exaggerating the size of this snake are often told, here are the facts: adults are
4-5 feet in length. Large snakes are 6 feet long with a maximum length probably under 8 feet. Newborn snakes are 12-15 inches
long. An average adult diamondback weighs 4-5 pounds. A real giant may tip the scales at 10 pounds or more.
Distribution & Habitat
The eastern diamondback ranges along the coastal lowlands
from southeastern North Carolina to eastern Louisiana, including all of Florida and the Keys. Until the 1970s, the diamondback
was common throughout much of its range; today it is only occasionally encountered. In some parts of its range it may be endangered
or even extirpated. Although the diamondback is found in most natural communities of the southeastern Coastal Plain, it is
most often thought of as an inhabitant of xeric (dry) uplands such as sandhills, clayhills and scrub. However, it will also
make occasional forays into swamps and marshes, especially when water levels are low. Diamondbacks have been seen miles out
at sea, apparently attempting to swim between islands. During the winter, diamondbacks take refuge in gopher tortoise and
armadillo burrows, stump holes, root channels, under palmetto thickets and other underground cavities.
(Below) Present range map of the E. Diamondback Rattlesnake.
Life History
Eastern diamondbacks give live birth to about 14 young between July
and October. Females may not breed every year. A rattlesnake, if unmolested, may live to the ripe old age of 20 years. The
eastern diamondback feeds on a variety of small mammals and some birds. The bulk of its prey consists of rabbits and cotton
rats. Diamondbacks hunt from a tight coil, remaining motionless, waiting to ambush prey that come within striking distance.
They may spend from one day, to as much as a week coiled in the same position.
Eastern diamondbacks have large home ranges that may encompass as much
as 500 acres. The home range of females is usually smaller than that of males. Males may move long distances during the late
summer, presumably in search of females.
Eastern diamondbacks are primarily terrestrial (living on the surface
of the ground), rarely climbing into trees and infrequently going underground during the summer. During winter, movements
decrease; rattlesnakes in the northern part of the range often stay below ground, but those further south still remain on
the surface much of the time.
The Rattle
Rattles probably evolved as a warning device to protect the snake from
being accidentally crushed by large, hoofed mammals. The rattle is composed of hollow, interlocking segments that click against
each other when the tail is vibrated. Rattlesnakes gain a new segment to the rattle every time they shed their skin. Since
they may shed from one to three times per year, one cannot accurately estimate the age of the snake simply by counting segments.
Segments also break off as the snake grows older.
Fangs and Venom
Like all vipers, rattlesnakes have a pair of long, movable hypodermic,
needle-like fangs that fold against the roof of the mouth when not in use. These fangs are connected to venom glands on each
side of the rattlesnake's head. Rattlesnake heads are large to accommodate these venom glands. During a strike, venom is pumped
by muscles surrounding the venom glands, through the fangs into prey. Rattlesnakes are also known as pit-vipers and possess
two heat-sensitive pits on either side of their face. These pits are sense organs and detect radiant heat, and aid rattlesnakes
in locating prey and increase striking accuracy. These pits are extremely sensitive and can distinguish differences in temperature
of less than 0.2 C. These advanced systems evolved in pit-vipers as a means of obtaining food. It is the most advanced system
that snakes have for capturing prey, and reduces the chances of injury to the snake.
The venom of rattlesnakes is actually a digestive enzyme and is a complex
mixture of proteins. The primary purpose of venom is to kill and digest prey. Venom is used in defense only as a last resort.
Some venoms attack the nervous system (neurotoxic) while others attack the blood and tissue (hemotoxic). The eastern diamondback,
like most rattlesnakes, has a combination of both types, but unlike most vipers, it has more neurotoxic properties.
Although the diamondback's real threat to public safety is very low
(many more people are killed every year by lightning strikes, bee stings and domestic dogs), the perceived threat by the public
is still quite high. Many biologists who have studied this species have found themselves in a position in which a rattlesnake
had ample opportunity to strike in self-defense. Those few who have been bitten were usually handling the snake when the bite
occurred.
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