Massasauga (Sistrurus catenatus)

Massasauga showing rattle
IUCN Red List species status – Least Concern LEAST

Top facts

  • The reptiles is the smallest rattlesnake in the United States and has the least toxic venom.
  • Unlike other rattlesnakes, the massasauga hibernates alone or in small groups.
  • Occasionally, the massasauga can be melanistic and may not possess the standard pattern seen in other individuals, and is almost entirely black.
  • The massasauga is considered threatened to some degree in all areas within its range.
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Massasauga fact file

Massasauga description

GenusSistrurus (1)

The reptiles (Sistrurus catenatus) gains its common name from the Chippewa word for ‘great river-mouth’, referring to this snake’s preference for wet habitats (2).

A medium-sized, stout-bodied snake (3), the massasauga is distinctively patterned with dark brown, light-edged, saddle-shaped markings on the upperside, the ground colour of which is usually grey, brown-grey or light brown (3). There are two or three rows of dark brown spots along each side of the body and both dark and light bands across the tail (2) (3). The underside of this species is dark grey or black (3) (4) and may be slightly marbled (5). Occasionally, this species is entirely black and does not possess the characteristic markings seen in most individuals (2) (3).

The head of the massasauga is broad (2) and heart-shaped (5) and there are black stripes extending from each eye along the sides of the head (3). The pupils of this species are vertically slit (3) (5), similarly to those of a cat (4). The tail of the massasauga has a grey-yellow rattle on the tip (5), which is composed of hard segments that make a distinctive buzzing sound when they are vibrated, indicating that the individual has been disturbed (2).

The juvenile massasauga is similar in appearance to the adult, but has a lighter colouration (3). At birth, the rattle on the tail of this species is made up of a single segment. Each time the individual moults, which usually occurs several times a year, a new segment is added to the tail and over time a functional rattle is formed (4).

The massasauga has three subspecies: Sistrurus catenatus catenatus, Sistrurus catenatus tergeminus and Sistrurus catenatus edwardsii (3).

Also known as
eastern massasauga rattlesnake.
Adult length: 45 - 100 cm (2)
Average adult length: 70 cm (2)
Newborn length: 16.5 - 24 cm (2)

Massasauga biology

The reptiles is usually active between mid-March or April and late October or early November (3), and throughout this period it is usually seen during the day, although in extremely hot temperatures it may also be active at night time (2). In late August or September, this species moves to its hibernation sites (3) which are usually located in low, wet areas (2). Unlike other rattlesnake species, the massasauga usually hibernates alone (3) (5) or in small groups of up to seven individuals (3), rather than in communal burrows (2). This species does not create its own burrows, instead hibernating in those made by crayfish and small mammals (4). Some individuals have been known to return to the same burrow to hibernate for consecutive years. Interestingly, this species is partially covered in water during hibernation which is thought to prevent individuals from drying out or freezing and may also help respiration through the skin (3).

The massasauga can mate in spring, summer or autumn (2) (4), although most reproductive activity generally occurs between May and June (2). After a gestation period of around 100 days (3), the ovoviviparous female (3) (5) gives birth to between 3 and 19 live snakes, although litters of 7 to 10 young are most common (2). The female massasauga is known to reproduce every two or three years (2) after reaching sexual maturity at three to four years old (3). The massasauga can live for up to 14 years (2).

The massasauga mainly feeds on small rodents (2) (3) (5), such as voles, shrews and mice (3), although it is known to take a variety of other prey items including snakes, frogs, birds and lizards. This species possesses heat-sensitive pits below its eyes which alert the individual to the location of its prey. A sit-and-wait predator, the massasauga is also known to locate its prey through sensing vibrations in the ground or detecting chemicals that are given off by the animal (5).


Massasauga range

The discontinuous range of the massasauga extends throughout the United States from the Great Lakes and the Great Plains in the north to southeast Arizona, Texas and northeast Mexico in the south (1).


Massasauga habitat

The reptiles has a strong association with wetlands (2), including bogs, fens, peatlands, meadows, marshes and swamps (1) (3). This species is occasionally found in dry, upland areas, such as savannahs and fields, which it uses for basking, foraging and giving birth, and it may also travel across these habitats to disperse into other areas (3). The massasauga is usually found at elevations below 2,100 metres (1).


Massasauga status

The massasauga is classified as Least Concern (LC) on the IUCN Red List (1).

IUCN Red List species status – Least Concern


Massasauga threats

The reptiles is threatened by habitat loss due to urbanisation, expansion of agricultural land (1) (2) (3) (5), damming (1) and wetland drainage (1) (3) (5). The extensive conversion of land within the habitat of this species has resulted in the fragmentation of populations, creating small, isolated populations that have no method of dispersal (3). The disjunct populations of this species often continue to decline due to various ecological problems until they become locally extinct (5). The change in land use practices has also disrupted the natural successional processes, reducing the suitability of many areas that were previously inhabited by this species (3).

As many of the wetland habitats occupied by this species are unprotected, the massasauga is at risk of becoming eradicated from even more areas (1). This species is regularly persecuted by humans in the belief that it is dangerous (1) (2) (3) (4) (5) and it is frequently killed in collisions with vehicles, as well as by destructive agricultural practices (1).The overcollection of the massasauga for commercial and recreational purposes is also known to have reduced the size of many populations (3).



Massasauga conservation

The reptiles is listed as endangered, threatened or a species of concern in every state within its range, offering this reptile a certain level of legal protection (3) (5).

The reptiles is thought to occur in some protected areas, although protecting more of its habitat would prevent future local extinctions from land conversion and wetland drainage (1). The restoration of areas previously inhabited by the massasauga may also help to boost population numbers, as could maintaining areas where this species is currently known to occur (3). Collaboration between conservationists and the owners of land inhabited by this species will help to ensure that land use practices do not harm the massasaugas in the area and will subsequently reduce the amount of mortalities caused by destructive agricultural methods (5).

To reduce the number of massasaugas that are harmed by humans, it has been recommended that an education and outreach programme be established to raise public awareness about the species and teach people how to live alongside this snake without conflict (3) (5). Furthermore, research into the life history of the massasauga and the ecological interactions that occur within its habitat could help to create appropriate conservation measures and ensure the survival of this unique reptile (3) (5).


Find out more

Find out more about the massasauga:

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Wetland with alkaline, neutral or only slightly acidic peaty soil. The alkalinity arises due to ground water seeping through calcareous rocks (rocks containing calcium carbonate).
The state of being pregnant; the period from conception to birth.
A winter survival strategy in which the animal passes the winter in a resting state. This period of inactivity is characterised by specific biological and biochemical changes including lowered blood pressure and respiration rate. In reptiles, this is also known as brumation.
Periodic shedding of (usually) the outermost body covering (such as feathers, fur or skin) during growth and development, or at specific times of the year.
Producing young that develop inside eggs, but the eggs hatch inside the female’s body and the young are born live.
A population usually restricted to a geographical area that differs from other populations of the same species, but not to the extent of being classified as a separate species.


  1. IUCN Red List (April, 2014)
  2. New York State Department of Environmental Conservation - Eastern massasauga Fact Sheet (April, 2014)
  3. Michigan Natural Features Inventory - Sistrurus catenatus catenatus (April, 2014)
  4. Michigan Department of Natural Resources - Eastern massasauga rattlesnake (April, 2014),1607,7-153-10370_12145_12201-32995--,00.html
  5. U.S. Fish & Wildlife Service - Eastern massasauga (April, 2014)

Image credit

Massasauga showing rattle  
Massasauga showing rattle

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