At MNA, our Mission is to protect special natural areas and the rare species that live there. The goals of our blog are to cover the latest environmental issues affecting these areas and provide information about the efforts of our volunteers. Our weekly “ENDANGERED!” column serves to inform you about the endangered and threatened plant and animal species found in and around these special natural areas, and how you can contribute to conservation efforts before it is too late.

Eastern Massasauaga Rattlesnake
By Yang Zhang

The Eastern Massasauga rattlesnake (Sistrurus catenatus catenatus), also known as the Massasauga Rattler, Black Massasauga Rattler, Michigan Rattler and Swamp Rattler, is Michigan’s only venomous snake.

A species of special concern in Michigan, the rattlesnake plays an important role in the ecosystem. They eat voles, mice and other rodents and help keep their populations in check. They are also part of a larger food web, serving as prey for eagles, herons and some mammals.

Photo credit: Nick Scobel

Physical Appearance:
Adult rattlesnakes are stout-bodied with broad, triangular heads and vertical pupils. Some measure 18-to-40 inches in length, with the average being 27.5 inches. The Eastern Massasauga’s back is marked with a row of large, black or dark brown hourglass-shaped blotches with three rows of smaller dark spots on its sides. A dark bar with a lighter border extends from its eyes to the rear of the jaw. Some adults, however, are all black.

Young rattlesnakes have small, yellow buttons, or rattles, at the tip of their tails. Adult rattles are grayish yellow, like pieces of corn kernels on top of dark rings. It is formed from loosely attached, hard, horny segments. A new segment is added each time the snake sheds.

Though its bite is not necessarily fatal to humans, the rattlesnake kills prey by releasing toxic venom. Rattlesnakes can even control how much venom is released when biting, and sometimes snake bites are dry bites, meaning that venom was not released.

Preferred Habitat:
Derived from the Chippewa language, “massasauga” (pronounced mass-a-saw’-ga) translates to “great river mouth” and refers to the snake’s preference for wet habitats.

In the cold wintertime, they hibernate in open shallow wetlands or shrub swamps. Massasauga rattlesnakes can be found in crayfish chimneys or small animal burrows, which are adjacent to drier upland shrub forests. In the late spring, massasaugas move upland to drier areas where they can find mice and voles, their favorite foods. You will most often find them “sunning” in open fields, grassy meadows or farmed sites.

In Michigan, the rattlesnakes only live in the Lower Peninsula. You may spot them at MNA’s Butternut Creek Nature Sanctuary, Big Valley Nature Sanctuary and Lambs Fairbanks Nature Haven.

Life Cycle:
An Eastern Massasauga rattlesnake can live 14 years, but nearly half of its life is spent in hibernation.

They hibernate during winter in burrows in moist lowland areas and emerge from winter dormancy in mid-April. In early October, they migrate back to hibernating areas, in some cases traveling more than 1.5 miles.

Female rattlers give birth to 8-to-20 live snakes in late summer instead of laying eggs. The breeding season usually occurs during May or June, but mating can occur almost any time from late April until September. It takes a young rattlesnake three-to-four years to become sexually mature.

List Status:
Historically, rattlesnakes were found in a variety of wetlands and nearby upland woods throughout the state’s Lower Peninsula. They are becoming rare due to loss of wetland habitat to development and agriculture and unregulated hunting and snake collection by humans. The massasauga is listed as a species of special concern by the Michigan Department of Natural Resources, and is protected by state law.

Protection Efforts:

The U.S. Fish and Wildlife Service is currently evaluating the snake’s population in the Great Lakes region to determine if it should be listed as a threatened species.

Current efforts to protect the species include working with land managers to practice techniques that avoid harming the rattlesnake and its habitat.

How You Can Help:
Massasaugas, like many snakes, are mistakenly perceived as a threat to humans, and the first human reaction may be to kill them. However, these snakes are shy and sluggish in nature. They avoid confrontation with humans and are not prone to strike. When rattlesnakes feel disturbed, they vibrate their tails, making a distinct buzzing sound. If you encounter a snake, leave it alone. If pets are in the area, it is important to confine them until the snake moves on.

MNA volunteers are currently working to protect this and other endangered and threatened species, and you can help too. Join our efforts as a volunteer removing invasive plants in the special natural areas where this species lives. Or, become a steward and take responsibility for planning efforts to maintain a specific MNA sanctuary. To find out how to get involved, visit our website.


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