Endangered Species
Midwest Region



Map of Region 3 Minnesota Wisconsin Michigan

Connect With Us

Facebook icon


Flickr icon




Twitter icon


YouTube icon



Buy Duck Stamps icon Endangered Species Day icon

Great Lake Restoration Initiative logo

Eastern Massasauga (Sistrurus catenatus)

Status: Candidate Species


eastern massasauga

Photo by Dick Dickinson

The eastern massasauga is a small, thick-bodied rattlesnake that lives in shallow wetlands and adjacent uplands in portions of Illinois, Indiana, Iowa, Michigan, Minnesota, New York, Ohio, Pennsylvania, Wisconsin, and Ontario.


Description of eastern massasauga status from 2011 Candidate Notice of Review

Federal Register 76:207 October 26, 2011: Review of Native Species That Are Candidates for Listing as Endangered or Threatened


Until 2011, the eastern massasauga was considered one of three recognized subspecies of massasauga. Recent information indicates that the eastern massasauga represents a distinct species, and we recognize it as such beginning in 2011. It is a small, thick-bodied rattlesnake that occupies shallow wetlands and adjacent upland habitat in portions of Illinois, Indiana, Iowa, Michigan, Minnesota, New York, Ohio, Pennsylvania, Wisconsin, and Ontario. Populations in Missouri, formerly included within the previously recognized subspecies of eastern massasauga, are now considered to be the western massasauga, Sistrurus tergeminus tergeminus.


Although the current range of S. catenatus resembles the species’ historical range, the geographic distribution has been restricted by the loss of the species from much of the area within the boundaries of that range. Approximately 40 percent of the counties that were historically occupied by S. catenatus no longer support the species. Sistrurus catenatus is currently listed as endangered in every State and province in which it occurs, except for Michigan where it is designated as a species of special concern. Each State and Canadian province across the range of S. catenatus has lost more than 30 percent, and for the majority more than 50 percent, of their historical populations. Furthermore, less than 35 percent of the remaining populations are considered secure. Approximately 59 percent of the remaining S. catenatus populations occur wholly or in part on public land, and Statewide and sitespecific Candidate Conservation Agreements with Assurances (CCAAs) are currently being developed for many of these areas in Iowa, Illinois, Michigan, and Wisconsin. In 2004, a Candidate Conservation Agreement (CCA) with the Lake County Forest Preserve District in Illinois was completed. In 2005, a CCA with the Forest Preserve District of Cook County in Illinois was completed. In 2006, a CCAA with the Ohio Department of Natural Resources Division of Natural Areas and Preserves was completed for Rome State Nature Preserve in Ashtabula County.


The magnitude of threats is moderate at this time. However, a recently completed extinction risk model, and information provided by species experts, indicates that other populations are likely to suffer additional losses in abundance and genetic diversity and some will likely be extirpated unless threats are removed in the near future. Declines have continued or may be accelerating in several States. Thus, we are monitoring the status of this species to determine if a change in listing priority is warranted. Threats of habitat modification, habitat succession, incompatible land management practices, illegal collection for the pet trade, and human persecution are ongoing and imminent threats to many remaining populations, particularly those inhabiting private lands. We do not believe emergency listing is warranted. We are changing the LPN from a 9 to an 8, reflecting the recent information indicating that this snake should be recognized as a species rather than a subspecies.


Life history, Ecology and Regulatory Information

Eastern Massasauga Candidate Form


Eastern Massasauga Fact Sheet


USFWS Chicago Field Office's Species Spotlight: Eastern Massasauga


Eastern Massasauga: Why Conserve  a Venomous Snake?


Eastern Massasauga Status Assessment (.pdf file 1.5 MB)


Questions and Answers About Conservation of the Eastern Massasauga


Eastern Massasauga Conservation Actions and Information

August 7, 2012: Long-term Research on Rattlesnake Life History Will Help Managers Plan Habitat Restoration


Eastern Massasauga - Spotlight Species Action Plan (October 2009) (9-Page PDF)


Private Stewardship Grant (May 2007): Restoring Southeast Michigan’s High Diversity Landscapes Through Collaborative Stewardship – Hillsdale, Jackson, Lenawee, Oakland, and Washtenaw Counties, Michigan


Private Stewardship Grant (May 2007): Reforestation and Wetland Restoration for Permanent Native Habitat in the St. Joseph River Watershed – Hillsdale County, Michigan; Defiance and Williams Counties, Ohio; Allen, Dekalb, and Noble Counties, Indiana


S6 Grant Project (2006): Response to Habitat Management by the Eastern Massasauga (Sistrurus catenatus) at Carlyle Lake, lllinois


S6 Grant Project (2006): Molecular Diversity among Massasauga Rattlesnakes: Nuclear Intron Analyses


Candidate Conservation Agreement with Assurances (CCAA) for Rome State Nature Preserve, Ashtabula County - Ohio (August 2006)


Final Environmental Assessment Approved for Implementing Candidate Conservation Agreements for Eastern Massasauga in Mid-Western States (July 26, 2005)


Eastern Massasauga Survey and Management Guidances

The Eastern Massasauga Rattlesnake: A Handbook for Land Managers (PDF 1.2 MB)


Recommended Standard Survey Protocol for the Eastern Massasauga, Sistrurus catenatus catenatus




Midwest Endangered Species Home


Last updated: May 26, 2015