Eastern Massasauga is a small rattlesnake species, less than 100 cm in total length with 9 enlarged scales (plates) on the head. Ground coloration of the dorsum ranges from a light tan to gray; the venter is black with white or cream-colored mottling. The dorsal surface of the body is covered by approximately 21–50 irregularly shaped brown or black saddles outlined by a blackish band.
Similar Species:
Eastern Massasaugas may be confused with Eastern Foxsnake (Pantherophis vulpinus) or Prairie Kingsnake (Lampropeltis calligaster), neither of which have a rattle on the tail. Eastern Massasauga and other rattlesnakes have vertical pupils. The Timber Rattlesnake (Crotalus horridus) head is covered in small scales compared to the 9 large plates Eastern Massasauga has.
Foxsnakes have narrow heads, round pupils, and no rattle on tail.
Eastern Massasaugas have vertical pupil, large plates on head, and rattles on tail.
Timber rattlesnakes have vertical pupils, small scales on head, and rattles on tail.
Distribution:
Eastern Massasaugas are broadly distributed over the Great Lakes region of North America, ranging north to south from Canada to south-central Illinois, Indiana, and Ohio.
Eastern Massasaugas primarily use open grassland habitats in the southern and western portions of their range. In the Midwest grasslands including wet prairies, old fields and shortgrass prairies.
Further north, Eastern Massasaugas occupy open forested habitats while in the central regions, fen, bog and river bottom habitats are used.
Natural History
Foraging and Diet
Eastern Massasaugas are ambush predators and will often remain stationary for days, presumably along rodent trails. They inject their hemotoxic venom to immobilize their prey, which include small mammals, birds, snakes, lizards, and amphibians.
Reproduction
Eastern Massasaugas may begin breeding as early as age 2-3. Females from some populations may reproduce every year but most are believed to reproduce every 2-3 years. Mating typically occurs mid-summer through fall, though mating has been observed in the spring on occasion.
Females birth a litter of live young the following fall. Litter size averages vary rangewide from 6.4 individuals in Missouri to 13.3 in Ontario. The largest observed litter was 20 individuals from a female in northern Illinois.
Hibernation
Eastern Massasaugas hibernate individually or communally, including with other species. Crayfish burrows, rocky crevices, rodent burrows, hummocks, old stumps, and rotten logs have all been reported as hibernacula. Most Eastern Massasaugas return to the same area each year.
Timing of ingress is weather dependent and has been observed as late as mid-November. Individuals may emerge from burrows during warm winter days.
Egress occurs March-April and during this time Eastern Massasauga remain near hibernacula, enabling them to retreat to burrows for thermoregulation.
Dangerous?
Eastern Massasaugas are venomous. Eastern Massasaugas are typically non threatening to humans, relying on being undetected to stay alive. They are cryptically colored and typically do not rattle, strike, or move, unless actually disturbed.
As with most wild animals, if threatened, they may bite, particularly if being handled. A study of 75 bites in Michigan* found that 80% of people bitten were males with an average age of 36, and 53% of the bites were on the hand. The last documented human fatality from an Eastern Massasauga bite was in 1935.
Topographic map showing the area near Carlyle, IL in 1948, prior to the damming of the Kaskaskia River.
Aerial imagery showing the area near Carlyle, IL in 2024. The Kaskaskia River floodplain is now covered by Carlyle Lake.
Photo of lesions caused by Ophidiomyces infection.
Threats:
The Eastern Massasauga was listed as “Threatened” under the U.S. Endangered Species Act in 2016, but has been protected at the state level beginning with WI (1975), NY (1983), IL (1994), OH and MI (1996). In Canada, the Massasauga was legally protected by the Ontario Game and Fish Act in 1990 and listed as ‘Threatened’ by the Committee on the Status of Endangered Wildlife in Canada in 1991.
Habitat loss is the primary threat across its range. Direct habitat destruction and conversion to agriculture or otherwise developed land, in addition to fragmentation of habitats pose major threats. Succession from old field to closed canopy woodland, changes in water level, and exotic invasive species also reduce available habitat.
Vegetative Succession:
While we often think of habitat loss as being directly human caused, the less obvious threat comes from succession. Without disruption, habitats naturally change over time from open canopy grasslands, to savannas, to closed canopy forest. Eastern Massasaugas require open areas to thermoregulate. Their prey also require these habitats to forage. Without natural processes such as fire, non native species and woody vegetation take root and close off the open habitat, eventually making it unsuitable for Eastern Massasauga and their prey.
Roads and Other Barriers:
Roads and other man made structures can fragment habitats, preventing movement and gene flow between populations. In addtion to blocking movement, roads can be a major source of mortality in some populations.
Killing and Over-collection:
Human perception of snakes as dangerous, vile creatures results in, at best, apathy towards their conservation. Human-snake interactions often end with the death of the snake. Eastern Massasauga are typically non threatening, relying on being undetected to stay alive. They are cryptically colored and do not rattle, strike, or move, unless actually disturbed.
On the other end of the spectrum, herpetological collectors desiring rare species have exploited known populations. Even some past academic research has negatively impacted populations.
Disease:
Infection by the fungus Ophidiomyces ophidiicola can cause Snake Fungal Disease which presents as lesions, crusty scabs, swollen face, ulcers, and ultimately leads to mortality.
Predators:
Common predators include raptors, coyotes, raccoons, fox, and skunks. Pigs, domestic dogs, and cats can also kill rattlesnakes.
What can you do:
The Eastern Massasauga was listed as “Threatened” under the U.S. Endangered Species Act in 2016, but has been protected at the state level beginning with WI (1975), NY (1983), IL (1994), OH and MI (1996). In Canada, the Massasauga was legally protected by the Ontario Game and Fish Act in 1990 and listed as ‘Threatened’ by the Committee on the Status of Endangered Wildlife in Canada in 1991.
Be an Advocate
Snakes are among the most feared and detested animals. Many people think “the only good snake is a dead snake.” Help combat that thought by educating others. Snakes are an important predator, helping to provide balance in the food web, control rodent populations and rodent-borne diseases. They are also important prey items for birds and mammals.
Snake venom also has potential medical benefits for humans. Venoms have already been used pharmaceutically for their antimicrobial, anti-inflamatory, anticoagulant, properties.*
Remind people to leave snakes alone. Most snakes are not likely to attack unless they feel threatened by you. If you handle a snake, it may feel the need to defend itself and it has limited options.
Habitat Protection
When visiting locations with Eastern Massasaugas, stick to trails to avoid trampling vegetation or accidentally stepping on snakes. Watch for wildlife basking on roads.
Habitat Creation
Planting native plant species in your yard can help a variety of wildlife.
Avoid Poisons
Poisons used to kill mice, rats, and other pests can harm their predators, including snakes, birds, and other mammals.
Can you Identify these look-a-likes?
Many people report seeing a Massasauga Rattlesnake but often it is another species. Many species of snake will even rattle their tail when threatened, and when it hits vegetation it can sound like a rattle. See if you can correctly identify the snakes pictured below.
Can you spot the hidden massasauga in each photo?
Massasaugas can be incredibly difficult to see in their natural habitat. With their cryptic coloring and ability to remain motionless, even experienced herpetologists can have difficulty spotting them.
