The Garter Snakes of Oaks Bottom

There is a moment, when something long and quick moves through the grass beside your foot, when the body decides before the mind does. Everybody has it. I have it. Then the mind catches up, and if you are lucky enough to be in Oaks Bottom on a warm morning, what you are looking at is a garter snake — one of the most harmless, most useful, and, if you will give it thirty seconds of honest attention, most beautiful animals in the whole refuge.

Oaks Bottom is Portland’s first urban wildlife refuge, a floodplain of meadow and marsh and blackberry tangle sitting right up against the Willamette. It is full of garter snakes. Most people walk the loop and never see one, which is a shame, because these are the animals quietly running the place.

🐍 There’s a quiz at the end — eight questions on what’s below. Jump to the quiz →

The Young One

Start here, because this is where most of them start. This is a young garter snake, still small enough to coil in the palm of your hand, tucked into wet moss and fern with its head up and its eye on me. Look at the coloring: olive and cream checkerboard down the flanks, a warm orange stripe running the length of the back, and a flush of red across the head. In this corner of Oregon that combination usually means a common garter snake of the red-spotted sort — though garters are variable enough that I will happily leave the subspecies argument to people with the animal in hand.

Here is the part that surprises people: nobody laid an egg to make him. Garter snakes give live birth. A female carries her young internally and delivers a squirming brood — a dozen is ordinary, and large females can produce a great many more — each one fully formed, fully venom-free, and fully on its own from the first minute. There is no parental care whatsoever. A newborn garter snake slides off into the grass and begins hunting worms roughly the size of itself.

Most of them will not make it. A young garter is food for almost everything at Oaks Bottom — the great blue herons stalking the shallows, the red-tailed hawks over the meadow, raccoons, bullfrogs, and every free-roaming house cat in the neighborhood. That is not a tragedy; that is the job. Garter snakes sit in the exact middle of the food web, converting slugs and worms into heron. Which is a strange and lovely thing to think about the next time you watch a heron lift off over the refuge.

The One in the Sprinkler Box

This one is not from the refuge at all. I found him in my sprinkler valve enclosure, down in the box with the pipes, apparently stuck — easy to drop into, harder to climb out of. So I reached in and picked him up.

That is the whole demonstration, right there. I picked up a wild snake with my bare hands, carried him into the house, set him on the kitchen table, and photographed him. He did not bite me. He did not try. He coiled, periscoped his head straight up to get a better look at the enormous idiot with the camera, and waited for the situation to resolve. Then I carried him out to the garden and let him go under the hostas, where the slugs are.

And look what the white table does for him: dark chocolate scales, two clean gold stripes down the sides, a pale throat, that keeled texture catching the light like brushed metal. Out in the yard he is a shadow moving under a leaf. Under kitchen light he is gorgeous. The lack of red and the emphatic stripes make me think Northwestern garter, our small local specialist — which, if right, is a very good tenant to have, because that species eats slugs and earthworms almost exclusively.

Think about what that means in a Portland garden. Slugs are the great devourer of Northwest gardening — the reason people buy pellets, scatter salt, sink beer traps. And here is an animal that patrols your beds at no charge, in silence, killing slugs all season, asking only for a rock pile to warm up on and to be left alone. Every snake you evict is a slug contract you just canceled.

Smell, in Stereo

This is my favorite photograph of the set, and it is worth slowing down for, because that tongue is not doing what most people assume. It is not a threat, it is not a stinger, and it is not tasting the air in any casual sense. It is taking a directional scent reading, and the fork is the entire trick.

When the tongue flicks out, each tip collects molecules from a slightly different point in space. The tongue retracts and delivers that sample to the Jacobson’s organ — a pair of chemical-sensing pits in the roof of the mouth. Two tips, two pits, two readings. If the left tip comes back richer than the right, the trail lies to the left, and the snake turns toward it.

That is smell in stereo. It is precisely what your two ears do with sound, and what your two eyes do with depth, applied to odor — and it is how a snake with no ears, modest eyesight, and its chin in the dirt follows the slime trail of a slug through leaf litter, in the dark, to a specific hosta. Watch a garter snake work and you will notice the flick rate changes: lazy and occasional when it is just cruising, fast and urgent when it has crossed something interesting. You are watching an animal think.

He was, of course, reading me. That is the other thing this photo records: a snake decided the shape looming over him was worth a proper sample before he committed to leaving.

The Bluff

And here is the adult, and I think she is magnificent. Jet black, glossy as lacquer, with a single orange-red stripe running the entire length of her body, drawn out across a fallen oak leaf and wet gravel. If you saw this animal in a photograph with no caption you would assume somewhere tropical. She lives in Portland.

She is also, in this frame, in full defensive display: body pulled into an S, head cocked back, holding her ground. It looks serious. It is theater. A garter snake’s defense kit, in order of preference, runs: freeze and hope you don’t see me; pour away into the nearest cover; flatten the body to look wider and more alarming than I am; and finally, if a hand actually closes around me, void the bowels and release musk — a smell engineered specifically to make you put it down, and it works beautifully. Striking is far down the list, and the mouth on the end of that strike is built for worms.

Let me be precise about the venom question, since it comes up. Garter snakes were long filed as non-venomous. They are better described as harmless: they produce a mild toxin in the saliva that helps subdue an earthworm or an amphibian, and they have no fangs and no delivery system worth the name. A bite from one is a scratch. In fifty-odd years of picking these animals up I have been musked more times than I can count and never once had cause for concern.

Meanwhile the garter snake is at the center of one of the most celebrated evolutionary stories in North America, and it is happening right here in the Pacific Northwest. Our rough-skinned newts carry tetrodotoxin — the pufferfish poison, one of the deadliest natural compounds known. Common garter snakes evolved resistance to it, so the newts got more toxic, so the snakes got more resistant, back and forth for millions of years, an arms race written into the DNA of two animals you can find on a wet trail in Oregon. Some of these snakes eat the newts and hold the toxin in their own bodies for weeks afterward, borrowing the poison as a defense. The harmless little snake in your flowerbed comes from a lineage that solved one of nature’s hardest chemistry problems.

Good Neighbors

So: harmless to you, murder on slugs, food for herons, free of charge, and beautiful in a way that only rewards people who stop and look. If a garter snake takes up residence in your yard, you have been paid a compliment. Leave a sunny rock, a brush pile, a board at the edge of the beds where it can warm up in the morning, skip the slug pellets, and you have a working partnership.

They ask for so little. Ectotherms run on borrowed heat: a garter snake spends the cold months tucked underground below the frost and emerges in spring to lie in the first warm patch it can find, doing nothing at all, charging up. Half the snakes you see are not going anywhere. They are sunbathing.

Mostly what I want to talk people out of is the flinch — or at least the part that comes after it, the reaching for a shovel. That reflex is the single biggest threat these animals face in a city, and it is aimed at a creature that cannot hurt you and is actively doing you a favor. Give it a beat. Let the body’s alarm pass, and look at what is actually in front of you: gold stripes on chocolate, or black lacquer with an orange line, or one small head lifted out of the moss to see who has arrived.

Go slow around the edges of Oaks Bottom on the next warm morning, and watch the sunny spots along the path. They are there. They have always been there. 🐍

Quiz: Do You Know Your Garter Snakes?

Eight questions, and every answer is somewhere above. Nobody’s grading you but the snakes, and they’re not judging.