Western Pygmy Rattlesnake

Image of a western pygmy rattlesnake
Safety Concerns
Scientific Name
Sistrurus miliarius streckeri
Viperidae (vipers and pit vipers) in the order Squamata (lizards and snakes)

The western pygmy rattlesnake is a small, colorful rattlesnake with a slender tail and tiny rattle. General color is light brownish gray, with a row of small, dark brown spots on the back and similar spots on each side. Most specimens also have a rust-colored stripe down the back. The belly is usually gray or dusky cream-colored, with numerous irregularly spaced bars. The head has a distinct black stripe that angles from the eye to the corner of the mouth, and a sensory pit located between each nostril and eye. The tail is thin and has a tiny rattle. Like other venomous snakes, they have “pits” on the sides of their heads, and the pupils are diamond-shaped in daylight (not round).

The disposition of this rattlesnake varies from individual to individual. Some will try to defend themselves vigorously by coiling, sounding their rattles, jerking their head, and striking at any movement. Others remain motionless and try to escape only when touched by a stick or snake hook. The sound of the vibrating rattle is a faint buzz, like the sound of a grasshopper, and can be heard for only about a yard away.

Similar species: Three other rattlesnakes are known from Missouri. The timber rattlesnake (Crotalus horridus) occurs statewide; adults are 3 to 5 feet long and have large rattles. Our other two rattlesnakes are massasaugas; they are rare and only found in northern Missouri.

Common Name Synonyms
Ground Rattler

Length: 15 to 20 inches. This is one of the smallest species of rattlesnakes in North America.

Where To Find
Western Pygmy Rattlesnake Distribution Map

Extreme southern Missouri along the border with Arkansas, and in the eastern Missouri Ozarks and St. Francois Mountains.

Prefers south-facing, rocky, partially wooded hillsides, near glades, in woods near rock ledges, and along the margins of forests and meadows. In late spring and early summer, it basks in rocky open areas, near brushpiles, or along roadsides near woodlands and glades. In July and August it tends to be nocturnal and can be seen crossing roads at night. It takes shelter under rocks in spring, early summer, and autumn. It also retreats into abandoned small mammal burrows, logs, and brushpiles.

Food includes a variety of small lizards, small snakes, mice, and occasionally small frogs and insects. Like other rattlesnakes, western pygmy rattlesnakes have hollow fangs to inject venom into their prey, and heat-sensitive pits between the eyes and nostrils that allow them to detect and accurately strike warm-blooded prey (such as rodents) even in total darkness.

Life Cycle

This species is normally active from mid-April to mid-October. Courtship and breeding apparently occur in the spring, and young are born from late August through September, with 3–7 young per litter. Newborns are paler than the adults, have a yellow tail tip, and are about 4–7½ inches long. In our state, it appears that females typically only breed every other year.

This small species is so secretive that few people encounter it. Although its bite is not fatal, a bite victim should seek immediate medical attention. The western pygmy rattlesnake should be respected and left alone. In extreme southern Missouri, this snake is called the “ground rattler.”

Rattlesnakes are considered the most evolutionarily advanced group of snakes. In addition to hollow fangs and heat-detecting facial pits, their tail rattles warn would-be predators not to attack them, saving the snake from having to bite and the enemy from being bitten. But rattlesnakes are often preyed upon by hawks, kingsnakes, and other predators.

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Similar Species
About Reptiles and Amphibians in Missouri
Missouri’s herptiles comprise 43 amphibians and 75 reptiles. Amphibians, including salamanders, toads, and frogs, are vertebrate animals that spend at least part of their life cycle in water. They usually have moist skin, lack scales or claws, and are ectothermal (cold-blooded), so they do not produce their own body heat the way birds and mammals do. Reptiles, including turtles, lizards, and snakes, are also vertebrates, and most are ectothermal, but unlike amphibians, reptiles have dry skin with scales, the ones with legs have claws, and they do not have to live part of their lives in water.