California red-sided garter snake facts (Are they poisonous?)

California red-sided garter snake

California red-sided garter snakes are more than just a pretty face. For many pet owners and herpetologists, they are great companions. With their distinctive coloration and lean, svelte shapes, California red-sided garter snakes deserve to sit well on anyone’s list of the bet pet snakes.

What is a California red-sided garter snake? – The California red-sided garter snake is a member of the family Colubridae. It is a subspecies of the common garter snake, a group of natricine snakes indigenous to North America. They are usually recognizable for their distinctive blue/yellow stripe pattern on a black and red background.

There’s a lot to discover when learning about the California red-sided garter snake. You might be wondering, because of its striking red pattern, if this snake is venomous.

You might also wonder where you are most likely to find one of these snakes in the wild. How should you set up an enclosure when caring for a California red-sided garter snake? Fortunately, you have all the information you need right here!

What do California red-sided garter snakes look like?

These mesmerizing snakes are known for their unusual and captivating scale patterns.

California red-sided garter snake close up

As fully-grown adult snakes, California red-sided garter snakes reach a maximum of about 3 ft. in length. But they are very slender, making them light-bodied and quick. These nimble snakes can dart with an agility and speed unknown to many other snakes.

The base color of a California red-sided garter snake is red, or a sort of red and black speckle. They have longitudinal blue or yellow stripes – depending on where you find them. This snake also often exhibits lines, spots and blotches of interlocking red and black. When it moves around, the colors writhe and wriggle. It can be quite spectacular!

People often mistake the California red-sided garter snake for a San Francisco garter snake. There is often some overlap between their two patterns. Also, patterns vary somewhat within a snake species. For example, sometimes the California red-sided garter snake is more prominently black than red. Sometimes, its blue stripe is hardly visible, and it is marked instead with a strong yellow stripe. These variations mean it can be easy to mistake this snake for one of its relations.

Are California red-sided garter snakes poisonous?

The California red-sided garter snake produces toxins that it releases into its prey when it bites. These substances may have a toxic effect on mice, shrews, frogs, voles and small fish (these form a part of this snake’s diet), but they are not strong enough to poison humans.

Because we are much larger, we are less susceptible to small amounts of weak poison. If a California red-sided garter snake bit you, you would certainly notice. Getting bitten by any sort of animal can be surprising. However, the shock itself would be the biggest indicator: the poison itself would only give you a mild itch.

After the shock wears off, simply clean the wound and bandage it up. California red-sided garter snake teeth are neither very long nor very strong. The puncture wounds are unlikely to be deep enough to require any acute medical attention. However, if you are concerned about the bite getting infected, visit your registered physician for an examination.

Are they dangerous?

California red-sided garter snakes are not particularly long, and are definitely not particularly wide of girth. As a result, they have a low body mass. Their petite appetites mean they mostly sustain themselves on small prey. Most California red-sided garter snakes eat a combination of insects, leeches, earthworms, eggs, and small mammals, reptiles and amphibians.

This gives an indication that the California red-sided garter snake is not a deadly snake. Also, as members of the Colubrid family, they are entirely non-venomous. Their humble dimensions and appetite, combined with their lack of any significant venom, makes them almost completely harmless.

If you step on a California red-sided garter snake by accident, there is a chance it will bite you in self-defense. However, if you show respect and caution to this snake, it will most likely pass you by.

The California red-sided garter snake is not considered a dangerous snake, to humans. It is mild-mannered and deferent. If threatened, it will almost certainly run away. Only if it feels cornered will it retaliate – this is a biological reaction, a product of evolution. And even if it does, you shouldn’t come to much harm!

Where are they usually found? 

California red-sided garter snakes are usually found on coastal dunes and marshes of… you guessed it – California! It may not be particularly well-traveled beyond the Californian border, but it is familiar with many of California’s counties.

Thamnophis sirtalis infernalis occurs throughout the state of California, in a distribution pattern known as ‘disjunct’. This basically means that there is a population in the north, in coastal Humboldt County, and a distinct population in the south, between Santa Barbara and San Diego County. The north population is also spread into Monterey County.

The reason for the ‘disjunction’, is because the California red-sided garter snake was mostly replaced by another subspecies of garter snake in southern Monterey. These two subspecies of garter snake live in conjunction, but they are genetically different snakes.


As it says above, the California red-sided garter snake is typically associated with permanent or near-permanent bodies of water. This means they occupy marshland, shallow water, and dunes, as well as lakes.

For example, the sag ponds in the San Andreas Fault rift zone and freshwater coastal marshes are their primary habitat. They like to escape into water to avoid attention, and to hide from possible dangers or predators.

You might find them further inland, in grassland and woodland areas.  

Are they good pets?

Yes! As snakes go, these are typically low-maintenance and mild-mannered. Not only this, but the California red-sided garter snake’s small size means it takes up less space, and a less expensive appetite to keep up with.

You can keep a California red-sided garter snake in a tank with a 20-gallon capacity. Of course, it is kinder to provide more space, if you can. Remember, in the wild, these snakes might travel over miles and miles during the course of a single year, let alone a lifetime.

What is the appropriate substrate?

The recommended substrate (bedding) for these snakes is cypress mulch. While this is a little more expensive, there are reasons that make it worth it:

  • Cypress mulch won’t dry out your snake’s enclosure in the same way as other substrates do.
  • It looks much cleaner and aesthetically pleasing than, for example, paper towels or newspaper.
  • It is also good for your snake’s epidermal (skin) health – it assists the snake in shedding.

What sort of water dish should you put in the enclosure?

Not only do they need to drink, but snakes require a very particular level of moisture in their skin. This varies from one species to the next. As California red-sided garter snakes are accustomed to living in, or close to, fresh water bodies, this must be emulated inside your snake’s enclosure.

Provide a water dish that is large enough for your snake to bathe in. This will assist your pet snake in maintaining a healthy, well-nourished epidermis!

Even if the humidity level is sufficiently high, your pet snake may occasionally want to fully submerge itself in water. A large water dish can make sure it has the opportunity.

What is the life expectancy of a California red-sided garter snake in captivity?

California red-sided garter snakes usually live somewhere in the region of 10 years – fairly close to the life expectancy of a dog or a cat. However, the longest-lived garter snakes have reached way past that, for as long as 17 years!

Do California red-sided garter snakes need a heat lamp in their enclosure?

Reptiles are cold-blooded. Many people expect ‘cold-blooded’ to indicate cold blood, but this is not strictly true.

Cold-blooded animals have a differently functioning homeostatic system to warm-blooded animals. A result is that they require external heat sources. Mammals, on the other hand, produce heat themselves.

A strange anomaly to the expectation is presented by those animals which bask in very hot sun – their blood temperature increases according to the temperature in which they bask. Imagine a lizard sitting under a 120°F sun. Its blood would actually be significantly warmer than that of a warm-blooded animal!

The upshot of all this is: yes, California red-sided garter snakes do require an external heat source. Even if the room which houses your snake is sufficiently warm, it is a courtesy to provide an extra direct heat source. This way, your pet snake can regulate its own temperature, by moving closer to, or further way from, the lamp.

What do California red-sided garter snakes eat?

As you learned earlier in this guide, California red-sided garter snakes have a variable diet. In the wild, what a snake eats depends largely on what it can find, and what it can overpower. They are not known to be fussy eaters. These snakes eat slugs, earthworms, leeches, minnows and rodents. They also happily eat various species of lizard and amphibian – including frogs’ eggs.

In captivity, it is unlikely that you will find a supplier who can imitate a wild California red-sided garter snake’s diet accurately. But the good thing is – you don’t need to!

California red-sided garter snakes can easily survive, and thrive, on a diet consisting primarily of frozen thawed rodents. These are available in a variety of sizes, and can easily be thawed shortly before feeding. However, it is a good idea to provide some variety, so your snake doesn’t get bored. Variety also ensures a broader nutritional profile.

Add in some night crawlers and feeder fish (these contain a handy enzyme called thiaminase, which breaks down vitamin B1). Note: do not feed your snake solely on feeder fish – this can be very unhealthy and ultimately deadly.

Garter snakes do NOT eat crickets, mealworms or insects.

Last but not least: garter snakes have cool scales

Well, all snakes do. But California red-sided garter snakes are unique in their scale structure and type. Their scales are keeled all the way down the length of the snake. ‘Keeled’ scales have a ridge running lengthways down the center.

What’s the point of keeled scales? That’s a good question. Unfortunately, there aren’t any good answers out there to match it. Some people have suggested that keeled scales play a role, however indirect, in snake survival.

The ridge effect reduces the sheen of the scales. This makes them duller in appearance that, in turn, makes these snakes harder to spot from afar. Being seen advantages some snakes; others bask in their camouflage. They are harder to see in the wild that, for these small and mostly defenseless snakes, has got to be an advantage.


That’s about all there is to know about the California red-sided garter snake. Or is it? If you have any more facts you’d like to share with us, feel free to write them in the comments below. Add your voice to the mix – join the conversation!

Do California red-sided garter snakes make good pets? Our verdict is: Yes! They make great pets. They are relatively small and mild-mannered, low-maintenance and cheap to feed – compared with some other snakes. If you want to hop onto the snake-keeper bandwagon, this may be a good place to start.

If there’s anyone out there – a friend, a family member – who is keen on snakes, be sure to send this guide their way. Or, if you’re more interested in keeping other types of snakes, there are plenty of available guides on our website. You can read all about how to keep rosy boas, ball pythons, or a different subspecies of kingsnake.

Either way, your feedback is appreciated. Happy snake-keeping!


Apparel & Accessories

Beds & Furniture

Cameras & Monitors




Health Supplies

Aquarium Pumps

Aquarium Filters

Aquarium Lights

Aquarium Heaters

Why Do Dogs Like Tug of War? Vet-Approved Benefits, Tips & Considerations
Odie Pet Insurance Review 2024: An Expert’s Breakdown
Ned, Fred, and Bed: An Unconventional Approach to Toilet Training
Why Does My Dog Rub His Face on Me? 5 Possible Reasons Explained
Funny Cats | Funny Ski Fails
Cake Decorating 101 with Funny Dog Maymo: Yummy Cake Recipe by Dog Chef
Adorable Pets You’ll Just Fall In Love With! Funny Pet Videos 2019
Cat Fails – Funny Cat Videos – Funny Animal Videos 2020