Michigan Snake Identification - Venomous or Not?

I am contacted by many people each year asking for help to identify snakes they find in their yard.  Many are just curious as to what animals call their yard home, or what they saw while camping.  I would be lying if I didn't mention that most just really want to know if they are in danger and often adopt the approach of "shovel first, questions later".  Is it "poisonous" or venomous is more often than not top of the list of questions they ask.  My hope is that this will address some of those questions and help provide a place for others to ask their questions and contact me more easily if needed.

If you don't care if it is venomous, still feel free to leave comments or contact me as directed below.  You may look at the pictures under the Reptiles tab to try and figure out what snake you have seen.

Michigan Venomous Snakes

Michigan only has one species of venomous snake.  That is one species out of the eighteen snake species that call Michigan home.  It is the eastern massasauga rattlesnake (Sistrurus catenatus).  Unfortunately, due to habitat loss, road mortality and persecution, the massasauaga rattlesnake is listed as a species of special concern and can only be found in very specific locations in the state.  These snakes are small, and very secretive.  It is highly unlikely that most Michiganders will ever encounter these animals.  They are also not present at all in the Upper Peninsula. 

Here are some general rules for identification when you are looking at a snake in front of you.  These rules only apply to Michigan and snakes that can be found in the wild.

1. Vertical pupil vs round pupil - Massasauga Rattlesnakes have vertical, cat-like, pupils.  Michigan's nonvenomous snakes do not.  Again, outside of Michigan, there are snakes that do not follow these rules.

Massasauga Rattlesnake

And a nonvenomous snake, the eastern milksnake.  This snake is commonly confused for a massasauga rattlesnake.

2.  Presence of a facial pit - The Massasauga Rattlesnake is a pitviper.  They have a heat-seeking pit that helps them localize their prey.  The are ambush predators, and will sit and wait for a small rodent to run by, sometimes at night, and their pits help them hunt.  Michigan's nonvenomous snakes do not have these heat-seeking pits.

Massasauga Rattlesnake

Northern Watersnake, nonvenomous - note the lack of a vertical pupil or pit

3. Divided anal plate and double tail ventral scales after the cloaca vs single anal plate and tail ventral scales after the cloaca. In normal terms, the nonvenomous snakes have a split or divided scale that covers their cloaca.  The cloaca is the opening (butt) of the snake where feces (poop) is excreted.  The scales after the anal scale will also be divided or doubled. Venomous snakes of Michigan have a single anal scale and single scales after.  I will obtain pictures of anal scales soon, but please refer to the above figure.

4. Presence of rattle - The Massasauga Rattlesnake has a rattle that produces a loud noise.  I will be sure to record one soon as well for you to listen to.  This trait is not as easy as it seems, as most other nonvenomous snakes will rattle their tails in leaves to mimic the rattling sound.  Also, young rattlesnakes just have one segment of rattle, or a button, and their tails will not make noise.  If you see a rattle, or hear a rattle, it is best to just walk away.

Massasauga Rattlesnake, with large rattle, saying "Stay Away"

Massasauga Rattlesnake, neonate or baby, with single button

 5.  Triangular head vs Rounded head - It is true venomous snakes often will have a triangular head.  Many nonvenomous snakes will flatten their neck and change their shape slightly to look more triangular.

Northern Watersnake with a fairly triangular head

Eastern Hognose Snake showing a triangular head

Remember, massasauga rattlesnakes have specific habitat preferences and needs.  They are not found all over the state.  They are small, secretive snakes, typically associated with wetland areas, swamps, bogs and fens.

Now, you are probably reading this and saying "BuckeyeHerper, you are crazy if I am ever going to be close enough to a snake to look it in the eye, or lift it's tail to check the butt."  I agree completely, but I do not feel this is a reason to kill the snake. If you aren't sure, just keep a safe distance and leave the snake alone.  Luckily snakes are not as aggressive as people typically think they are.  They will run more often than not.  If they do happen to stand their ground, you can very easily walk away or around them without any worry.  If you are comfortable, everyone has a digital camera or cell phone these days, and it is easy to take a quick picture from a safe distance.  You can then compare your picture with pictures on this and other websites, or email it to me or others for assistance.

Again, if you aren't sure, just keep your distance.  These snakes are very rarely encountered, and chances are you have just found one of the more common nonvenomous snakes.  Despite what you might have heard,Michigan also does not have any cottonmouth, water moccasins or copperheads.

If you have any further questions, or want to share pictures or stories, please feel free to leave a comment below or email me at foltjr AT gmail.com .