By Misi Stine, Environmental Educator and member of the MN Herpetological Society
I am surprised it took me this long to write about my favorite Minnesota snake, the Timber Rattlesnake (Crotalus horridus). It is the only venomous snake in Minnesota that was found in surveys in the last several decades, and has been confirmed to have a breeding population. Minnesota is at the northern most end of its range.
Technically, timber rattlesnakes are one of two venomous snakes that call Minnesota home. The eastern massasauga is the other, but there has only been one confirmed sighting, occurring in 1936 in Wabasha. There were surveys in 1993, 2002, and 2003 that did not provide evidence of additional massasaugas.
It is important to note that unless you are in prairie bluff habitat, forested bluffs, or south facing rock outcrops in the southeastern part of the state (see the range map), or in the driftless area, you won’t see a timber rattlesnake. Having gone out looking for them while herping (looking for reptiles and amphibians in the wild), I can tell you that they are not easy to find and the trek to the best locations to observe this species can be difficult. Here is a link to a recently posted video by a fellow herper, Dav Kaufman, of rattlesnake dens in southeastern Minnesota: https://www.youtube.com/watch?v=PQx18VjkOCE
When looking for a timber rattlesnake you will be looking for a large thick bodied snake with a triangular shaped head, with heat sensing pits on each side of its head between the eye (which has a vertical pupil), and the nostril, and narrow neck, averaging 31-48 inches long. They range in color from gray, to yellow, to dark brown with dark colored bars, keeled scales, and the tail is solid black with a rattle.
Timber rattlesnakes in Minnesota are often confused with non-venomous species that share their range including the milksnake (Lampropeltis Triangulum), western fox snake (Pantherophis vulpinus) and gopher snake (Pituophis catenifer) . Please note, none of these species have sensory pits on the face, elliptical pupils (for reference, pupils should not be considered a means to reliably identify if a snake is venomous or not) or a rattle. However, these species, like many will shake their tails in the leaf litter as a defense mechanism, effectively sounding like a rattlesnake. It is important to know how to use multiple features to identify any snake species. In addition, these other species have blotches on their bodies, they are not barred.
Historically, there were more timber rattlesnakes, and they had a larger range than the eight counties currently on the map, but primarily due to human activity the population has declined. There are conservation efforts on several fronts, from education on the importance of timber rattlesnakes in the ecosystem to teaching ways to coexist with venomous snakes, and enacting laws to protect them. While the Minnesota DNR and others are actively engaged in restoring bluff prairies to improve the habitat needed for basking and increase reproductive success and conducting research into the species.
Here are five fascinating facts about Timber rattlesnakes:
It is incorrect to say that you can age a snake by the number of rattles. Each time a rattlesnake sheds it creates a new button, and as the snake moves around its environment buttons may break off, so the only thing you can tell by the rattle is how many times the snake has shed since the last button broke off.
Not all snakes lay eggs, rattlesnakes (as well as seven other Minnesota species) give birth to live young in membranous sacks. Rattlesnakes are also known to stay with their young until their first shed at about 10 days of age.
There is new research to show that rattlesnakes are far more social that what has been thought to be true. Here is an article on the social lives of rattlesnakes: https://blogs.illinois.edu/view/7447/1886253864. This site also has cameras where you can watch rattlesnake dens live, all day every day during their active time of year. These cameras are part of research that is currently taking place through UC Davis at rattlecam.org. This is an opportunity for the general public to observe rattlesnake behavior in real-time.
It is believed that if you step on a snake, it will bite you, but what was learned in a research project using a prosthetic leg is that out of 175 times that a rattlesnake was “stepped on” only six times did it result in a bite. In fact most of the time the snake froze or tried to get away rather than respond defensively (click here to read the full article).
Not all bites from a venomous snake result in being envenomated, approximately 1/3 of all bites are dry bites. A dry bite is when no venom is injected. For a bite to be considered a dry bite there would be no symptoms only 1-2 holes in your leg where the fang(s) stuck you. A dry bite cannot be confirmed until at least 8 hours has passed because snake bites are dynamic and symptoms can evolve over a period of time. If you have been bitten by a venomous snake here is a link to the steps you should follow: https://files.dnr.state.mn.us/natural_resources/animals/reptiles_amphibians/snakebites.pdf
Please know that unprovoked bites from timber rattlesnakes are rare, there were 21 bites between 1982-2020, nine were the result of handling the snake bare handed, which would not be considered unprovoked. Fatalities are even more rare. In fact, the last time someone died from a timber rattlesnake bite in Minnesota was in 1868.
I have had the privilege to see timber rattlesnakes on multiple trips to southeastern Minnesota and northeastern Iowa. Every time it is seeing the best of what wild Minnesota has to offer. I sincerely hope you will have the privilege to witness this magnificent creature in its Minnesota home.
References
Avoiding and Treating Timber Rattlesnake Bites. (2020). Retrieved from Minnesota Department of Natural Resources: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://files.dnr.state.mn.us/natural_resources/animals/reptiles_amphibians/snakebites.pdf
Cal Poly, Central Coast Snake Services, Dickinson College. (n.d.). Project Rattle Cam. Retrieved from https://rattlecam.org/
Dav Kaufman. (2024). Dav Kaufman's Reptile Adventures. Retrieved from YouTube.com: https://www.youtube.com/watch?v=PQx18VjkOCE
Essig, R. (2023, October 3). New research shows rattlesnakes are social animals. Retrieved from Prairie Research Institute: https://blogs.illinois.edu/view/7447/1886253864
HARTOUNIAN, A. (2024, May 17). Lessons from rattlesnake class in the American Southwest. Retrieved from wpr.org: https://www.wpr.org/news/lessons-from-rattlesnake-class-in-the-american-southwest?fbclid=IwZXh0bgNhZW0CMTAAAR2pZEIge5cVdJr0GKvt_-cYaU83sYdK4S2V9DOGpGHQaf9nkB8-f-I-tgo_aem_AdPaNyfXhPrTu2W7qndAn5JrVdYG5Bt4zAfbsPPBHjLYWqgkTxnnVi8orpHI87Vo1zZAFFMji6QEcvx07bpf
(2018). Snakes and Lizards of Minnesota. St Paul Minnesota: MInnesota Department of Natural Resources. Retrieved from Minnesota Department of Natural Resources: chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://files.dnr.state.mn.us/natural_resources/animals/reptiles_amphibians/snake_lizard_mn.pdf
Timber Rattlesnake, Rare Species Guide. (n.d.). Retrieved from Minnesota Department of Natural Resources: https://www.dnr.state.mn.us/rsg/profile.html?action=elementDetail&selectedElement=ARADE02040