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Dusky Pigmy Rattlesnake

Dusky Pigmy Rattlesnake

Sistrurus miliarius                                               Photo Fiona Sunquist ©


Also known as ‘buzzworms’ and groundrattlers, pigmy rattlesnakes are short, stout-bodied snakes about 20-30 inches long.  They are pit-vipers, so called because of the facial pit located between each eye and nostril.  The pits are heat sensitive organs that can detect differences of less than 0.22 C (0.4 F) Because prey animals, especially warm-blooded prey have body temperatures different from the environment these organs allow pit-vipers to detect potential victims.  Rattlesnakes, cottonmouths and copperheads are all pit vipers.

Pigmy rattlesnakes are quick-to-strike, feisty little snakes, but their bite is rarely fatal.   Small fangs and small amounts of hemotoxic venom make this snake less dangerous than its larger relatives, though it can still pose a danger to children, dogs, and cats. Hemotoxic venom causes a breakdown of blood cells and leads to bruising and internal bleeding.

Unlike the smooth-skinned coral snake, the pigmy rattlesnake has rough (keeled) scales so its skin looks dull, not shiny. The head is broad and triangular The background color is grey, marked with a row of large, dark circular spots down the center of its back and a fainter row of similar looking spots down each side.  The tail ends in a small, delicate looking rattle, which produces a faint sound like a buzzing insect.  Unlike diamondback rattlesnakes, pigmy rattlers almost never warn approaching people by rattling – they are more likely to remain motionless or twitch their head from side to side. 

Dusky Pigmy Rattlesnake Head

                                                                            Photo Fiona Sunquist ©

One amazingly detailed study conducted on Hog Island in South Florida by students and faculty of Stetson University marked over 1,000 snakes in six years.

In the Hog Island study, individual snakes were marked with pit tags – small glass encapsulated microchips about the size of a grain of rice - implanted into the snake’s body cavity.  When a scanner is held near the pit tagged snake, the tag transmits a signal containing a unique number that is then displayed on the scanner. 

The snakes in the Hog Island study spent an incredible amount of time coiled, waiting for prey to come to them. Individual snakes were observed to remain coiled in the same place for as long as two or three weeks!  The Hog Island snakes fed primarily on anolis lizards and frogs, but in other places, pygmy rattlesnakes have also been found to feed on spiders, centipedes, frogs, lizards, snakes, nestling birds and mice.

On Hog Island most snakes hunted coiled on the ground, hidden in some kind of cover. But some foraged from arboreal positions, lying above the ground on branches, fallen logs or palm fronds.

Dusky pigmy rattlesnake baby pigmy coiled

                                                                           Photo Claire Sunquist ©

They sometimes moved 8-12 feet up into trees, especially during flood periods.  Individual snakes were found to have preferred hunting positions.  Researchers even coined the term “log pigs” for some individuals who were consistently found on logs in a hunting position or ‘foraging coil’.   Others lay with their bodies alongside the log, with head up, presumably waiting for an animal to use the log as a runway.  In open grassy areas, snakes hunted by backing themselves into a grass clump, head facing outwards into the opening.

Like any ambush predator, pigmy rattlesnakes must wait for suitable prey to come within striking distance.   To increase their chances, pigmys use their tail as a lure to encourage prey to approach them. Other sit-and-wait predators such as the alligator snapping turtle and juvenile cottonmouths use the same technique.

One of the interesting observations made by the researchers on the Hog Island study is the differences in the time it takes for prey to become immobilized, depending on whether it is warm blooded or cold blooded.  A mouse will become immobilized within 30-40 seconds, whereas lizards and frogs can be still moving 15-20 minutes after being struck.   Pigmy rattlesnakes release their prey after striking, then scent track it to the site where it was overcome by the effects of the venom.  The Hog Island researchers found a number of dead frogs and lizards that had obviously been struck by snakes but had moved beyond the range of the snake’s tracking ability.

Pigmy rattlesnakes bear their young alive. Only about half the females give birth in any single year.   In Florida, litter size ranges from 2-12 with an average of six. Newborn pigmy rattlesnakes are tiny; they weigh 4 to 5 grams and when coiled are not much larger than a quarter

The young remain clustered near their mother for several days after birth, until they have shed for the first time.  They quadruple their weight in the first year and reach adult size by the time they are two or three years old.

Point of Information

While pigmy rattlesnakes are fairly common in a variety of Florida habitats, they are also quite abundant in the garden section of large stores. Look for them coiled in the larger black pots.


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Wildlife of Florida 2011
Wildlife of Florida 2011
Fiona Sunquist
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Wildlife of Florida: Lizards
Fiona Sunquist
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