Slithering Through the North: A Guide to Venomous Snakes in Canada

Canada is home to 26 different species of snake. This is a relatively low number compared to many other countries. Most snakes live in Southern Canada because the rest of the country is too cold for them to survive.

Only four of the 26 snake species in Canada have venom, including the Eastern Massasauga rattlesnake, the prairie rattlesnake, the Northern Pacific rattlesnake, and the desert nightsnake. Half of these snakes live in British Columbia. Alberta and Ontario each have one venomous snake species. 

This article lists Canada’s four venomous snakes. I will discuss their biology, habitat, how you can identify them, and what you should do if you encounter one. Many non-venomous snakes in Canada mimic venomous ones for defense, so it’s important to recognize the difference.

1. Eastern Massasauga Rattlesnake

The Eastern Massasauga rattlesnake’s (Sistrurus catenatus) venom is cytotoxic. Cytotoxins are substances that damage living cells. Your white blood cells are considered highly cytotoxic because they destroy foreign or infected cells in your body. An Eastern Massasauga rattlesnake’s venom can do something similar to your healthy cells.


The Eastern Massasauga is smaller than the average rattlesnake. It has a thick, muscular body and grows to about 19-25 inches (48.3-63.5 cm) in adulthood. 

Its coloration is usually grey, yellowish tan, or dark brown. However, some individuals have melanism, which gives them a pitch-black color. The pattern on an Eastern Massasauga’s back includes butterfly or heart-shaped spots, which are one or two shades darker than their primary color. 

Like any rattlesnake, the Eastern Massasauga’s tail end has a distinct rattle that will shake when it feels threatened.

Southern Ontario is also home to the Eastern Foxsnake, which has a similar appearance. However, Eastern Foxsnakes are harmless, so be careful identifying them in the wild. An Eastern Foxsnake has triangular or rectangular spots instead of butterfly-shaped ones. It also doesn’t have the segmented rattle at the end of its tail.


Eastern Massasauga rattlesnakes live in Southwestern Ontario. They’re attracted to grasslands with long natural grass and marshes. Pregnant females typically lay in the sun on the grasslands, while males and non-pregnant females stick to the marshes. 

Most Eastern Massasauga encounters occur around the Great Lakes. They are most common near Ontario’s Georgian Bay and Lake Eerie.


Eastern Massasauga rattlesnakes are quite fearful of people. For this reason, the chances of one biting a human are low. They typically opt for the “flight” response before they try to “fight.” When a bite does occur, it’s usually because the person attempted to pick up the snake or accidentally stepped on one.

To avoid bites, give the snake lots of space. Never chase, harass, or touch the snake. Simply walk the other way or give it a wide berth, so it doesn’t feel threatened.

Accidents can happen, especially when the snake hides in tall grass. Fortunately, the snake will give you plenty of warning with its rattle before it decides to strike.

Always wear high-top, closed-toe shoes while hiking in Eastern Massasauga country. This way, if you accidentally step on one, its fangs are less likely to pierce your skin. Keep your eyes on pets and children to ensure they don’t irritate any snakes. 

You can also gently brush tall grass with a stick to help you see any snakes without aggravating them. This may also encourage any hiding snakes to move away before you put your feet there. 

Bite Symptoms

Eastern Massasauga bites are potent and can be fatal if left untreated. Luckily, their bites are treatable if you seek medical attention as soon as possible. Their cytotoxic venom will attack cells once it enters a body. This leads to severe pain, swelling in the bite area, and hematomas.

While you’re waiting for help, restrict movement to prevent the venom from spreading. Remove any tight clothing or jewelry from the bite area to let it swell as it needs to. Swelling is a natural immune response, and you should not try to restrict it without professional advice.

You may have heard of people sucking the venom out of a snake bite, don’t try to do this. Sucking venom won’t work and puts another person at risk of envenomation. 

Like bee stings, snake bites can cause anaphylaxis if the person is allergic. So, medical professionals will monitor for these symptoms while they administer antivenom treatments. 

2. Prairie Rattlesnake

Like the Eastern Massasauga, prairie rattlesnakes (Crotalus viridis) also have cytotoxic venom. However, prairie rattlesnake venom has the additional danger of also being hemotoxic. Hemotoxins specifically target red blood cells and can stop your blood from clotting or make it clot more than it should. 


Prairie rattlesnakes have some similar physical characteristics to the Eastern Massasauga. However, they are typically lighter in color, ranging from light tan, yellowish olive green, sand-colored, and medium brown. They are also larger than Eastern Massasaugas, with an average length of 39-59 inches (99-150 cm).

The patches on their backs are more rectangular and have a darker shade of brown. Prairie rattlesnakes may also have a darker-colored band behind their eyes. Similarly, these snakes will have a hard, segmented rattle at the ends of their tails.

Bullsnakes are harmless snakes that live in Alberta and mimic prairie rattlesnakes. However, the color difference between a bullsnake’s body and its patches is more distinct than that of a Prairie Rattlesnake. Moreover, bullsnakes are also larger. 


Prairie rattlesnakes live in Southern Alberta and some parts of Southwestern Saskatchewan. You can find them on plains, grasslands, and rocky areas. They hide in abandoned animal burrows and rocks. So, you should never stick your hand into a hole in the ground in prairie rattlesnake territory.


Prairie rattlesnakes are nocturnal during the hot summer months but come out during the day when the weather cools down. If you go for a nighttime hike during a Southern Alberta summer, take a flashlight, so you don’t miss any snakes. However, don’t take it for granted that there will be no rattlesnakes out on a summer day.

Prairie rattlesnakes can climb. That means that you might see them basking on rocky ledges. Keep your eyes up as well as down. Never reach for a rock ledge if you can’t see what’s on it. 

Like Eastern Massasaugas, prairie rattlesnakes would rather flee than fight. Although they are a little bit braver than their cousins in Ontario.

Similarly, wear high-top, closed-toe shoes and give the snakes lots of space if you see them. Aging Prairie Rattlesnakes may lose their rattle sound as they get older. Therefore, avoid Alberta’s wild snakes altogether. Mistaking an older prairie rattlesnake for a harmless bullsnake can have dire consequences. 

Bite Symptoms

A Prairie rattlesnake’s cytotoxic and hemotoxic bite can cause several alarming symptoms, including the following:

  • intense burning pain and swelling
  • difficulty breathing
  • irregular heartbeat
  • numbness 
  • a metallic taste in the mouth

It’s important to call emergency services immediately if you suspect a bite.

A prairie rattlesnake venom’s hemotoxicity can cause blood clots, red blood cell destruction, tissue necrosis, and organ damage. This is why it’s extremely important not to delay medical intervention. Some people may have an anaphylactic reaction in rare cases. 

As frightening as a bite can be, try to stay as calm as possible if you’ve been bitten. Increasing your heart rate may increase the venom’s potency, so do what you can to keep that under control. 

Prairie rattlesnake bites are completely treatable when medical professionals arrive within 30 minutes to an hour. The fatality rate for these bites is only about 1 in 100.

3. Northern Pacific Rattlesnake

The Northern Pacific rattlesnake (Crotalus oreganus) is also known as the Western rattlesnake. Northern Pacific rattlesnake bites pack a punch that includes hemotoxins, neurotoxins, and myotoxins

Neurotoxins attack the nervous system, which can lead to paralysis, slurred speech, and potentially irreversible brain damage. On the other hand, myotoxins target muscle cells and can break down muscle fibers.


Northern Pacific rattlesnakes are one of the largest subspecies of rattlesnakes. Their size can range anywhere from 23 to 65 inches (58-165 cm). Young snakes have distinct oval-shaped patches along their backs but these fade as they age. The patches are still visible in adults but are not as distinct as they were when they were younger.

Their color tends to run more greenish and ranges from greenish brown to green-grey and reddish brown. The oval-shaped patches on their backs gradually become bands as the pattern gets closer to their tail. Like any rattlesnake, their tails end in a rattle that shakes when they feel threatened.


Northern Pacific rattlesnakes live in Southern British Columbia, mainly in the Okanagan and Similkameen regions. This species roams in a few different biospheres. Typically, you can see them in forest and field areas. On hot days, they will go to shorelines to cool off. 

Sightings of these snakes are rare in British Columbia. Habitat loss and the destruction of their dens from human activity have caused a significant population decline in the area. 


Despite their powerful bites, Northern Pacific rattlesnakes are pretty passive creatures. They won’t bite a human unless they’re provoked. Typically, these snakes come out during the dawn and dusk hours, but they spend most of their time hidden in dens.

The Northern Pacific rattlesnake only bites about 5 people per year in the Province of British Columbia. So, the chance of you getting bitten while on a hike is low. That being said, don’t underestimate the incredible power of their venom. Please respect their space and take the proper precautions while in their habitat.

Bite Symptoms

Northern Pacific rattlesnake bites are rare, but if one occurs, immediate emergency treatment is crucial. Untreated bites can lead to organ damage, brain damage, paralysis, and death. So, please seek emergency services if you suspect a bite. However, with treatment, your chances of recovering from a bite are good.

Symptoms of a Northern Pacific bite may include:

  • intense pain
  • local swelling
  • blistering 
  • slurred speech
  • nausea
  • vomiting 
  • fainting

Because their bites can induce loss of consciousness, always hike with a buddy while treading in their territory. 

The earlier a bite victim gets antivenom, the better their chances. So, I would advise preparing an emergency plan before hiking in this snake’s region. You are unlikely to encounter this snake, but it’s better to have a plan and not need it than to be left without an emergency plan if needed.

4. Desert Nightsnake

The desert nightsnake (Hypsiglena torquata) is technically not venomous. It doesn’t inject venom through its fangs like most venomous snakes. Instead, it has poisonous saliva that can be dangerous to humans in high doses. A desert nightsnake’s poisonous spit is mild and will rarely cause harm to a human. 


Their appearance is similar to a rattlesnake, but they’re significantly less dangerous and smaller. They also don’t have the distinctive tail-end rattle. Their size range is about 11-25 inches (28-63.5 cm) in adulthood.

They can be light brown, grey, beige, and yellowish tan. They have dark brown bow-shaped patches along their back and round spots along their sides. Desert nightsnakes also have large dark patches at the backs of their heads and a stripe across each eye.


Desert nightsnakes are only in a small part of South-Central British Columbia. Their population is low, and they’re currently at high risk of extirpation. They generally stick to arid rocky and sandy areas, hence the “desert” in their name. 


These snakes are nocturnal and rarely interact with humans. This behavior makes it difficult for researchers to estimate how many wild individuals remain in Canada. 

They’re extremely docile and are unlikely to bite even if handled. However, this doesn’t mean that you can pick them up without care. Never touch or pick up any wild snake unless you’re a wildlife expert. 

Remember, Canadian desert nightsnakes face extirpation. The snake may not be much of a threat to you, but you could be a threat to the snake. Improper handling and “kidnapping” from the wild will only contribute to their decline. 

Bite Symptoms

Although a desert nightsnake won’t inject venom, there is a risk of getting its toxic saliva into an open wound, so clean the skin near the bite. Be careful not to accidentally scrub its toxins into the wound.

Desert nightsnake venom is not particularly toxic to humans. Nevertheless, it’s still a poison that you should avoid. Like any poison, it will cause harm if a large amount of it enters the body. 


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