Red-Sided Garter Snakes and the Narcisse Snake Dens of Manitoba
Red-Sided Garter Snakes in Canada
The garter snake is an interesting and often attractive reptile that is sometimes kept as a pet. The animal is non-venomous and is considered to be harmless. In winter, it hibernates in an underground den with other snakes. From early fall to spring, the area around the Narcisse Snake Dens in Manitoba contains the largest concentration of red-sided garter snakes in the world. Tens of thousands of animals spend their winter hibernating in the dens of the area. When the reptiles awaken in the spring, they form dense mating balls in which up to a hundred males are twined around a single female.
The range of the red-sided garter snake extends from eastern British Columbia all the way across Canada to the Maritime provinces, although the reptile is absent from Newfoundland. The animal is also found in the Northwest Territories as well as in the United States. It's the most abundant and widespread snake in Canada. In western British Columbia the reptile is replaced by other garter snakes, including close relatives of the often beautiful red-sided garter snake.
Narcisse Snake Dens in the Mating Season
Garter snakes often have a variable appearance. For example, the red-sided garter snake doesn't always have red sides while garter snakes without "red-sided" in their name sometimes do.
Physical Features and Habitat
The scientific name of the red-sided garter snake is Thamnophis sirtalis parietalis. It's a subspecies of the common garter snake, or Thamnophis sirtalis. Although the appearance of the animal varies, it's often dark green or black in colour with a yellow stripe along the top and sides of its body. On the side of its body between the stripes, there may be a row made of orange or red bars alternating with dark-coloured bars. This row gives the snake its name but is sometimes absent. It's missing in many animals near Narcisse, as the video above shows.
The snake is said to be a habitat generalist. It's found in a variety of apparently dissimilar areas, including forests, fields, scrubland, rocky areas, and wetlands. It sometimes ventures into gardens. Each habitat has at least one thing in common. It contains places where a snake can hibernate safely without being harmed by snow, frost, low temperatures, and predators. These places are generally uncommon, which is one reason why garter snakes usually hibernate in groups. The area around the town of Narcisse contains some great hibernation sites for the snake.
The common garter snake exists as different subspecies. Information that refers to the "common garter snake" is often—but not always—true for all of the subspecies. The different subspecies of a species have relatively minor genetic differences from one another. They can interbreed and produce fertile offspring.
Senses, Diet, and Predation
The garter snake has a forked tongue that is generally red or orange in colour with a black tip. The animal frequently flicks its tongue out of its mouth in order to sense the environment. The tongue picks up molecules in the air and inserts them into the Jacobson's organ in the roof of the mouth, enabling the reptile to respond appropriately to the stimulus. Snakes have internal ears for hearing and are sensitive to touch and vibrations. Garter snakes have quite good vision.
Diet and Predation
Red-sided garter snakes are carnivores and hunt for frogs, toads, salamanders, earthworms, and leeches. They also eat bird eggs, baby birds, small mammals such as rodents, and sometimes fish.
The snake has many predators. These include foxes, raccoons, hawks, crows, larger snakes, turtles, bullfrogs, and even large fish.
Hibernation or Brumation
The bedrock around the Narcisse area is located near the surface of the Earth and consists of limestone. Water percolating into the limestone has created sinkholes and underground caverns that are a haven for snakes in winter. The reptiles are found in caverns beyond the Narcisse dens. In some cases they hibernate near or in human communities, which has led to conflict.
Some specialists prefer to use the term brumation instead of hibernation for the winter dormancy in reptiles, since there are metabolic differences in the body of a hibernating mammal and a brumating reptile. The word "hibernation" is still widely used by the general public in reference to snakes, however. Their winter den is known as a hibernaculum.
Exploring the Narcisse Snake Dens
People shouldn't pick up snakes except in very special circumstances and when guided by an expert. A mistake in identification could be deadly.
The red-sided garter snake quickly moves out of the way when it encounters humans, except under special circumstances such as those found at the Narcisse snake dens. It's best to admire the reptile from a distance instead of touching it. If a garter snake is picked up, it may release a mixture of feces and musk from an opening near the end of its body called the vent. The musk in this unpleasant mixture has a repellent smell, which lingers on human skin.
If an attacker persists in its attempts to trap the snake, the reptile may bite. A garter snake has small teeth that either don't penetrate human skin or penetrate just the outermost layer. I've never been bitten by a garter snake so I can't describe the experience personally, but people report that the bite is "a surprise rather than painful" or even "pitiful". A seven-year-old boy shows his reaction to a red-sided garter snake bite in the video below.
Garter snakes have a Duvernoy's gland instead of a venom gland. The gland's secretion and its effects are still somewhat puzzling for researchers. The secretion from the glands may be toxic. Some people experience skin irritation from contact with the snake's saliva. This doesn't seem to be a common occurrence, however.
A Boy Gets Bitten by a Garter Snake
Although the snakes at the Narcisse Snake Dens may bite, this appears to be a very rare event. The Snake Dens representative in the video below says that the snakes don't bite and that even if they do they can't pierce the skin. The bite shown above was Nathan's first, even though he had visited the dens and handled the snakes several times before.
The Narcisse Snake Dens
Narcisse is a small town in the province of Manitoba. It's located next to Highway 17 about 103 km north of Winnipeg, the capital of Manitoba. The snake dens are in turn located about 6 kilometres north of Narcisse. Signposts guide visitors to the dens, which are a major tourist attraction.
A 3 km walking trail enables visitors to view four dens as well as the surrounding landscape. The gravel trail is made of crushed and packed limestone. It's flat and is suitable for strollers and wheelchairs as well as pedestrians. Benches along the trail allow people to rest.
The route may look like a normal nature trail at first. At certain times of the year, however, visitors will notice snakes beside the trail and often on the trail as well. The walking path travels by each of the four dens but not right up to them so that the snakes aren't disturbed during a critical moment in their lives. There is an observation area beside each den to enable people to watch the reptiles and to take photos. The dens are below the level of the observation platform and are sometimes referred to as snake pits.
Reproduction at the Dens
At the end of hibernation, the males emerge from the dens first and wait for the females. As soon as a female appears, males surround and cover her in an attempt to mate. The female releases a chemical known as a pheromone that attracts the males. The writhing collection of snakes that results is known as a mating ball.
The mating ball moves along the ground and even rolls down inclines as the female struggles to move and the males struggle to mate with her. In a large mating ball, a rustling of scales can be heard as the snakes's bodies move over each other. The female is usually bigger than the males, but she's often hidden by her companions.
After mating has finished, the female leaves the area to feed. She may give birth within two to three months, but sometimes the sperm is stored for longer before being used. Garter snakes are ovoviviparous. The eggs hatch within the female's body and the young are born live. The number of youngsters ranges from only a few to as many as eighty, The female leaves them to fend for themselves soon after they're born. Like the females, the males disperse after mating has finished. Both genders lead a solitary life until it's time to hibernate again.
The young snakes are reproductively mature at between two and three years of age, if they live that long. In the wild, garter snakes often have a short lifespan. The average lifespan in the wild seems to be around two years while in captivity it's generally between six and ten years.
Handling a Garter Snake Without Hurting it
Never try to pick up a snake unless you are absolutely positive that it's harmless! It's also important to think about the animal's welfare before you pick it up and while you handle it.
Visiting the Snake Dens or Pits
The snakes at the Narcisse Snake Dens can be seen in September before they begin hibernation. The best time to see them is on a sunny day in late April and early May when they emerge from their dens and mate, however. Not only are they most numerous and active at this time of year, but in addition they are generally preoccupied with reproduction and aren't bothered by the presence of humans. A warmer day means the snakes will be more active. Unlike humans, the reptiles can't regulate their body temperature by internal processes.
I find the idea strange for a wildlife management area, but visitors are allowed to pick up snakes that they discover along the trail near the dens (although not in the buffer area immediately beside the dens, where people are prohibited). Picking the animals up would certainly add interest to the visit, especially for children. I hope the snakes are treated well by visitors, though. Interpreters are on the trails when the snakes are active in the spring and visitors are encouraged to treat the animals gently, as shown in the video above.
Visitors should be aware that the area around the snake dens has limited facilities for humans. There are primitive washrooms on the site and a water pump at the start, but no food is available. Visitors should bring their own snacks and beverages. A pair of binoculars and a camera would also be useful during the walk. The snakes at the dens can be seen with the unaided eye, but binoculars would give a better view of the action.
Red-Sided Garter Snakes as Pets
Red-sided garter snakes have a reputation as a harmless animal, which is mostly deserved. They are also active and frequently inquisitive reptiles that are interesting to watch. For this reason they are sometimes kept as pets.
I urge people who want to keep a red-sided garter snake as a pet to find a breeder and buy a captive-bred animal. Collecting wild snakes is illegal in some places or is illegal without a permit. In addition, I think it's unfair to bring a wild animal into captivity, even when that animal is a snake.
People who keep red-sided garter snakes as pets report that many of them don't release musk or bite when they become used to being gently handled by people. This isn't always true, however. Some snakes never like to be handled.
Some Points to Consider: A Checklist
A prospective garter snake owner needs to do a lot of research. Buying a reptile as a pet should never be an impulsive decision. Some important points to consider before bringing a snake home include the following:
- size of the terrarium
- temperature in the habitat
- food sources, size, and safety
- feeding frequency
- bedding type
- other necessary items for the terrarium (such as a water bowl and places for the snake to hide and climb)
- a cleaning routine for the habitat
- special care during skin shedding
- recognizing upcoming brumation
- special care around brumation time (if brumation takes place)
- why, when, and how to encourage brumation if it doesn't occur naturally
- diseases to watch for and steps to take if they appear
- dealing with bites (Since a snake's teeth point backwards, the head of an attached snake should be gently moved forwards to remove the teeth from the skin.)
A prospective snake owner should also investigate the reputation of a breeder and the location of the nearest vet who has experience in treating reptiles. It's good to get recommendations for both these people if possible. It's also a good idea to check the accuracy and relevancy of any information that's discovered. When I did an online search for reptile veterinarians in my area, the address and phone number of my previous vet was listed. Unfortunately, the vet has retired and the building that he used is no longer a veterinary clinic.
Food for Pet Red-Sided Garter Snakes
Finding suitable food for garter snakes is a special consideration. It's important that all food given to a captive snake is safe and that there is a reliable source of the food. The food must be both nutritious and free of dangerous toxins or parasites.
Pet owners say that their red-sided garter snakes stay healthy on a diet consisting mainly of small frozen and thawed mice, which many pet stores sell. This means that people who have a garter snake in their home don't have to watch mice bring killed by the animal. Although snakes can swallow quite large items, pinkies (very young mice that have not yet grown hair) may be needed for some garter snakes. Very small snakes will likely need pieces of pinkies.
Of course, feeding a snake frozen mice still means that the mice have been killed, although this was probably done humanely. Another advantage of feeding snakes dead prey is that it prevents them from being injured by an animal that is trying to escape. There's no way around the necessity of feeding animals to snakes. Since snakes are carnivores and hunters, they have to be fed other animals if they're kept as pets.
Earthworms or Night Crawlers
People also feed their garter snakes earthworms or night crawlers (Lumbricus terrestris). Many sources state that red wigglers are toxic to garter snakes. Red wigglers (Eisenia fetida) are worms that are often used in vermiculture.
Fresh or frozen and defrosted fish may be given to garter snakes, although it's best if these are used as a treat. Unlike mice, fish aren't nutritionally complete for garter snakes. They can also make the animal's feces very smelly. Pet owners must check that their fish of choice doesn't contain an enzyme called thiaminase. Thiaminase breaks down thiamine, or vitamin B1. A vitamin B1 deficiency in a garter snake can be deadly.
While the subspecies of a species have minor differences from each other, these differences may be interesting. The extinction of a subspecies and the loss of its unique genes is a sad event.
Status of the Wild Garter Snake Population
The International Union for Conservation of Nature (IUCN) classifies animals according to their nearness to extinction. Thamnophis sirtalis is classified in their "least concern" category. Although the red-sided garter snake has many predators, it's also capable of producing many offspring, which keeps its population size fairly constant. Unfortunately, another subspecies of the common garter snake—the San Francisco garter snake, or Thamnophis sirtalis tetrataenia—is considered to be endangered.
The presence of garter snakes in human communities may create problems. A crowd of snakes arriving for hibernation and their antics in the spring are sometimes unwelcome, especially when the animals enter buildings. In this situation they may be treated as a pest.
Sometimes snakes and humans can coexist peacefully. In 2015, a hibernaculum containing over 400 garter snakes was discovered by workers on a dyke near my home. As is often true for hibernacula, the snakes belonged to different species and subspecies. The mixture included the common garter snake. The reptiles were collected by a wildlife organization and kept safe. They were released in the same location where they were found once the weather was warmer and construction had finished. It would be nice if conflicts between humans and garter snakes could always be resolved so equitably. The reptiles are interesting animals to observe and study.
Questions & Answers
© 2016 Linda Crampton