Sistrurus catenatusMassasauga

Geographic Range

Eastern Massasauga rattlesnakes are native to the Nearctic region. They are found throughout the central United States, from southern Canada to western Arizona, south to the Gulf Coast of Texas, and east to Pennsylvania. (Harding, 1997)


Eastern Massasauga rattlesnakes are usually found in damp lowland habitats, including bottomland forests, swamps, bogs, fens, marshes, sedge meadows, and wet prairies. The name 'massasauga' means 'great river mouth' in the Chippewa language. These habitats are used by massasaugas from early fall to late spring. During the spring and summer months these snakes often move into drier, more upland habitats, such as grasslands and farm fields. (Harding, 1997)

Physical Description

Eastern Massasauga rattlesnakes are members of the pitviper group. This large group of species are members of a larger group, the vipers. Vipers all have enlarged, hollow fangs at the front of their mouth which are used to inject a modified saliva into their prey. This saliva is venomous and causes their prey to die. The gaping of the mouth as they bite causes the fangs to swing forward, jabbing the prey, then muscles in their head inject the venom. Most vipers wait until their prey are dead before eating them. Pitvipers also have sense organs on either side of their head, the 'pits', that detect heat. This is important because pitvipers tend to eat warm-blooded prey and they use their pits to locate them. Some pitvipers are known as 'rattlesnakes' because they have a series of segments at the end of their tail that are loosely connected and make a hissing rattle sound when vibrated by the snake. New rattle segments are added each time the snake sheds its skin, so by counting the rattles one can estimate how old the snake is. Rattle segments can be lost, though, so if a snake has 8 rattle segments it may well be more than 8 years old. All rattlesnakes also have cat-like pupils which are elliptical and oriented vertically in the eye. (Harding, 1997)

Eastern Massasauga rattlesnakes are thick-bodied, medium-sized snakes, ranging in length from 47 to 100 cm as adults. This snake is marked with rows of dark, irregular blotches running the length of their back on a background color of gray, gray-brown, or brown. These dark blotches, and dark stripes on the tail, are often outlined in a lighter scale color, making them stand out against the background color. Many are strikingly beautiful. Their coloration makes them very difficult to see in the places where they bask or hide. Belly color is usually black with light mottling and their heads are triangular in shape. Some individuals are almost completely black. The scales are keeled (with a raised ridge down their center) and males are slightly longer than females. Newborn eastern massasauga rattlesnakes are born at 18 to 25.6 cm in length. They are similar to the adults but overall lighter in color and have only a single 'button' of a rattle. At birth young Eastern Massasauga rattlesnakes are capable of using their fangs and venom. (Harding, 1997)

These snakes are sometimes confused with eastern timber rattlesnakes, which have tails that are almost completely black. Eastern Massasauga rattlesnakes have striped tails. (Harding, 1997)

  • Sexual Dimorphism
  • sexes shaped differently
  • Range length
    47 to 100 cm
    18.50 to 39.37 in


Eastern Massasauga rattlesnakes mate in the spring and fall. The females hold the babies inside their bodies for about 3.5 months then, rather than laying eggs as some snakes do, they give birth to live young. Females give birth to their 5 to 20 young in abandoned mammal burrows or fallen logs while living in their drier, summer habitats. Young snakes become sexually mature (able to have babies) in their third or fourth year. (Harding, 1997)

  • Breeding interval
    Females reproduce only every other year.
  • Breeding season
    Eastern Massasauga rattlesnakes breed in the spring and fall, they give birth in August and early September.
  • Range number of offspring
    5 to 20
  • Average gestation period
    3.5 months
  • Range age at sexual or reproductive maturity (female)
    3 to 4 years
  • Range age at sexual or reproductive maturity (male)
    3 to 4 years

Female Eastern Massasauga rattlesnakes nurture and protect their young inside of their bodies while they're developing. The young remain near their mother for a few days after birth and then move away (disperse).

  • Parental Investment
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female


Eastern Massasauga rattlesnakes have been known to live in captivity for 20 years, but lifespan in the wild is unknown. (Harding, 1997)

  • Range lifespan
    Status: captivity
    20 (high) years


Eastern Massasauga rattlesnakes are active from April through late fall. They hibernate through the cold months alone or in small groups, often in crayfish or mammal burrows in lowland habitats. Hibernation sites are often close to water level and below the frost line. They return to the same hibernation site year after year. They can swim well, but spend most of their time basking on high ground, such as on muskrat lodges, grass clumps, or rocks. They are most active during the day but may become more active in the morning and evening during the hot months of summer. Eastern Massasauga rattlesnakes tend to stay in relatively small home ranges.

Communication and Perception

Eastern Massasauga rattlesnakes may communicate among themselves with chemical and physical cues, especially during breeding. These snakes detect prey with their sense of smell and with the heat-sensitive pits found on their faces. They are also sensitive to vibrations and have relatively good eyesight. Rattlesnakes also communicate warning signals and aggression to attackers with their rattling tail and by coiling up and striking. (Harding, 1997)

Food Habits

Eastern massasauga rattlesnakes eat mainly small mammals such as voles, white-footed mice, jumping mice, and shrews. They sometimes also take other snakes, frogs, birds, bird eggs, and insects, especially when they are younger and smaller. Young eastern massasauga rattlesnakes entice frogs and toads to come closer by twitching their tail tips. These snakes usually strike their prey, then wait for them to die before eating them, but prey that aren't likely to fight back, such as baby mice or frogs, may be eaten without using venom. (Harding, 1997)

  • Primary Diet
  • carnivore
    • eats terrestrial vertebrates
  • Animal Foods
  • mammals
  • amphibians


Some large snakes, such as racers and milk snakes, may eat rattlesnakes. Hawks, herons, raccoons, and foxes may be able to kill them as well, and deer and pigs will trample rattlesnakes when they see them. However, by far the biggest threat to eastern massasauga rattlesnakes is humans, who have relentlessly pursued and killed these snakes throughout their range. Eastern massasauga rattlesnakes mainly avoid confrontation, they are usually not aggressive. They rely on their camouflage coloration to avoid being seen and will most likely freeze when approached. If an enemy comes too close these snakes will attempt to escape or will vibrate their tail as a warning. Most eastern massasauga rattlesnakes are hesitant to strike unless seriously harassed. (Harding, 1997)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

These rattlesnakes are very important in controlling populations of rodents and other small mammals in their natural habitats. (Harding, 1997)

Economic Importance for Humans: Positive

Eastern Massasauga rattlesnakes are very important in controlling rodent populations throughout their range. Research on rattlesnake venom helps develop new medical technologies to treat heart conditions and other diseases. (Harding, 1997)

Economic Importance for Humans: Negative

Rattlesnake bites to humans are rare, but are potentially dangerous. Most people who are bitten by rattlesnakes have been attempting to hurt or handle them. Eastern Massasauga rattlesnakes have a potent venom but have relatively short fangs that often fail to penetrate clothing and can deliver only small amounts of venom with each bite. Rattlesnake bites are painful, with swelling and tissue damage near the bite site. Anyone who has been bitten by a rattlesnake should stay calm and seek immediate medical attention (NOT try to cut open the wound and suck it out, a popular folklore). Most people recover completely from rattlesnake bites.

Most rattlesnakes are shy and retiring and killing rattlesnakes is entirely unnecessary. Rattlesnakes found near homes may be removed to other areas, though it is likely that it is the humans who have intruded on a snake's traditional habitat. (Harding, 1997)

  • Negative Impacts
  • injures humans

Conservation Status

Eastern Massasauga rattlesnakes are threatened or endangered throughout their range, as a result of human persecution and habitat loss. Their wetland habitats are often lost to draining projects and their upland habitats to agriculture and suburban development. Michigan is one of the few places where Eastern Massasauga rattlesnakes seem to be doing reasonably well, though populations are declining here as well. The status in Michigan is 'special concern'. In the USA, this rattlesnake is a candidate species being considered for federal protected status.


Tanya Dewey (author), Animal Diversity Web.



living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map


a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.


an animal that mainly eats meat


uses smells or other chemicals to communicate


having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

  1. active during the day, 2. lasting for one day.

a substance used for the diagnosis, cure, mitigation, treatment, or prevention of disease


forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.


having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.


the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.


(as keyword in perception channel section) This animal has a special ability to detect heat from other organisms in its environment.


offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).


marshes are wetland areas often dominated by grasses and reeds.

native range

the area in which the animal is naturally found, the region in which it is endemic.

seasonal breeding

breeding is confined to a particular season


remains in the same area


reproduction that includes combining the genetic contribution of two individuals, a male and a female


lives alone


a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.


uses touch to communicate


that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).


Living on the ground.


an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).


movements of a hard surface that are produced by animals as signals to others


uses sight to communicate


reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.


Harding, J. 1997. Amphibians and Reptiles of the Great Lakes Region. Ann Arbor, Michigan: The University of Michigan Press.