Air Date: Week of July 13, 2001

For eight months of the year, garter snakes in Manitoba, Cananda, hibernate underground, stacking themselves one on top of the other, like cordwood. Only for a few weeks each year do they come out of hiding to answer the call of the wild. It doesn't take very much for these snakes to whip themselves into frenzied mating balls. One man has made the study of these slippery mating rites his life's work. Reporter Sy Montgomery trails along with the Snake Scientist.

Transcript

CURWOOD: Lions, elephants, crocodiles. These are the craters that make for gripping nature documentaries. But don't forget about the lowly garter snake. Garter snakes? Drama? Don't laugh. Just listen to this report from Sy Montgomery, about the garter snakes of Manitoba, Canada, and the researcher who studies them.

MONTGOMERY: For six weeks each spring, on a windswept prairie in Southern Manitoba, one of the most astonishing spectacles in the natural world unfolds.

MASON: If you look over here, you basically see a huge knot. I'd say that's probably the size of maybe a person's living room couch, so I don't know, there's probably, there might be 2,000 snakes in that mass of snakes moving up there.

MONTGOMERY: That's zoologist Bob Mason. I'm standing with him at the edge of a limestone pit filled with, perhaps, 20,000 slithering snakes.

MASON: It could be some more large aggregations of them here.

MONTGOMERY: Wow.

MASON: Here's a big hole that I saw some of them here.

MONTGOMERY: Huge, oh my God! They're coming out of it like a volcano. They're just erupting out of this hole.

MASON: They're erupting out of this hole, yep. There you go.

MONTGOMERY: How many animals do you think are here?

MASON: Probably several hundred in just this one little hole.

MONTGOMERY: Everywhere we look, harmless black and yellow stripe red sided garter snakes are awakening from an eight month sleep. They've spent the winter stacked like cordwood in underground caverns beneath the frozen earth. Now the foot-long snakes slither upward through tiny cracks and holes in the limestone. They find themselves at last on the floor of these rocky pits, depressions ranging in size from large manmade quarries, to something your lawn mower could fall into.

The males wake first. And when the females emerge, the snakes perform one of the strangest courtship rituals in the animal kingdom, one that Bob Mason has been documenting for 19 years.

MASON: So the mating ball, like that one over there, occurs where this female has emerged from the den here, and there's so many males on top of that female, and she's writhing around that it ends up taking on a ball like appearance with that writhing of snakes. And so we call that a mating ball. And so, when you're on a slope like we are right now, that mating ball can get so frenetic that the snakes will actually tumble down the slope just like a ball.

MONTGOMERY: And balls of mating snakes do roll down the sides of the pit. A river of reptiles writhes like living spaghetti on the pit's floor. But the scene grows stranger yet. Half a dozen people are picking up snakes by the handful.

MASON: If we all swoop in on them we can get them.

VOICES OF BOB AND COLLEAGUES COLLECTING THE SNAKES: "If we swoop in on them we can get 'em. Who is this big girl? Come here, my dear?"

MONTGOMERY: Volunteers and fellow scientists come from around the world to work with Mason, often putting in 16-hour days during these precious frantic weeks. At the moment, they're stuffing their snakes into pillowcases, a convenient method to transport them to a makeshift field laboratory.

MASON: We go to the Salvation Army and we go in and buy out all their pillowcases. And when we go up to the cash register, the person at the cash register would say, "um, that's an awful lot of pillowcases." And I just say, "boy, you never can have enough pillowcases." And they say, "okay."

I stopped telling people what I really did with these things a long time ago. They were just appalled. So it's better that they think you're some weirdo with a pillowcase fetish than even a bigger weirdo that actually watches snakes have sex for a living.

MONTGOMERY: Mason's research has yielded some extraordinary discoveries and earned him the title of "The Snake Scientist." Back at Oregon State University, his office door is papered with snake cartoons. His computer sports a garter snake screensaver. And the walls and shelves are littered with snake posters, figurines, stuffed toys.

MASON: Most of my life is made up of teaching and doing laboratory research. I just live for those times when I can get out and do our field work here and get away and just get completely immersed in this kind of science.

MONTGOMERY: Mason's fieldwork with the snakes has revolutionized our understanding of these common, but little understood, animals. For the 41-year old scientist, it all began when he was a kid exploring the fields and swamps of Connecticut, and often bringing a few specimens home.

MASON: So I'd have to admit, when you bring the snakes home in your pockets and then they get out. Or you take your dungarees off and you leave them in the laundry pile, then mom grabs the laundry and out pops a snake; or a snake runs out of the washing machine, that can be exciting for family life, but not the best for family harmony, let's just say.

MONTGOMREY: Years later Mason's Ph.D. thesis took him to the snake dens for the first time. The long cold winters forced the cold-blooded snakes to congregate in these limestone caverns. The situation makes for an unparalleled natural laboratory.

MASON: In fact, you can pick up a courting pair and they'll mate right in your hands.

MONTGOMERY: But how do the snakes in the mating ball figure out which one in a hundred animals is the female? The answers to questions like these have come from collecting thousands of pieces of data about these snakes. Bob and his team measure everything from their size, weight and temperature, to the chemistry of their skin secretions and blood.

Back at the field lab, Mason hunches over and deftly grabs a snake with one hand, holding a syringe in the other.

MASON: They have a vein just like a person would get a blood test out of your arm. They have a nice vein right in the middle of their tail that we can put this very thin little needle in.

MONTGOMERY: Once it's drawn, the snake's blood is spun in a centrifuge that runs off the cigarette lighter in the team's truck.

[SOUND CENTRIFUGE RUNNING]

As for that question of how the males find the females, 12 years ago, Mason discovered that these snakes, and possibly many other species of reptiles, are using natural chemicals called pheromones to communicate with one another. That's why they flick their tongues.

MASON: That picks up chemical cues, in this case the pheromone from female's back, and then they draw the tongue back into their mouth. And on the roof of the mouth there's two little holes that are the entrance to what's called the vomeronasal organ. So things like the skin lipids that don't have any smell to our nostrils will have a chemical smell to the vomeronasal organ. So it's very-- it's adapted to sensing and detecting these non-volatile chemical cues.

MONTGOMERY: Mason's discovery of the first pheromone ever isolated from a reptile also showed that the snakes lay down scent trails that other snakes follow. Year after year they use these trails to find the same exact den where they over-wintered the year before.

But there are many more garter snake mysteries yet to solve.

MASON: Here's one that's probably a she-male.

MONTGOMERY: Yes, that's what he said, "she-male." There's strange stuff going on in this mating ball.

MASON: Well, a she-male is something that-- a phenomenon that we discovered-- yep, this is one-- is a phenomenon we discovered, oh, several years ago. So what they do though is they attract the courtship of the other males. They actually smell like they're females.

MONTGOMERY: But why would a male produce a female hormone? The males who do so, Mason discovered, are all newly emerged from the earth, and they're cold. Mason thinks they're tricking the other warmer males into forming a living blanket to heat them up. But watching all this courtship can be lonely for a snake scientist.

MASON: I have to admit, for a snake scientist it can be somewhat difficult to find a partner that is as enthusiastic or at least even mildly enthusiastic about your work as you might be, especially when you're beginning a date and somebody says, "well, I know you're a biologist. What exactly-- what kind of animals do you work with?" And then you say, snakes. And they, "well, maybe this is not going to go as far as we might like to think it is.

MONTGOMERY: Happily though, the chance to help Mason study these snakes attracts a number of volunteers each year. One of them is now Mason's fiancZ.

MASON: I don't think there's too many people that can say they met their future wife in a sea of swarming snakes that are all intent on reproducing. So I think that-- I would like to think that's kind of a romantic site I think.

MONTGOMERY: For bringing him both his science and his sweetheart, Mason is the first to acknowledge that he owes these snakes big time. So when the snakes needed help, he jumped into the fray.

[SOUND OF CARS PASSING UNDERNEATH]

MASON: Well, right now we're directly across from the main den sites here at the Narcisse Wildlife Management area, and we're directly in the ditch, basically, of Provincial Highway Number 17, which is a main artery that heads north out of the city. And the reason we're here is because the snakes in the spring and the fall leave the den sites and then migrate in all directions away from the den, and have to get across this busy highway, which you can hear the cars rushing by now.

MONTGOMERY: So many snakes were killed each spring and fall crossing Highway 17 that in some years road graters had to clear their corpses away so that cars wouldn't skid on the bodies.

MASON: This is of course a huge problem that's a manmade problem. And what happened was the local folks here-- I remember the quote was just that they said it just-- it wasn't right. It just wasn't right to have these snakes being killed on the road.

MONTGOMERY: So the local people and government agencies got together with Mason to try to solve the problem. The solution: drill tunnels under the roadbed so the snakes could cross beneath the road. At first the snakes were reluctant to forsake the nice warm asphalt and enter the cold, dark tunnels. But Mason's science came to the rescue. By laying down a trail of snake pheromone, the reptiles couldn't resist the new route.

[SOUNDS OF CARS PASSING UNDERNEATH]

MASON: It was just a super story of all the people pulling together for these little garter snakes, of all things. And who would have thought that would happen.

[SOUNDS OF CARS PASSING UNDERNEATH]

MONTGOMERY: There was a time when the snakes here were considered vermin. Not that long ago, folks would pour gasoline down the snake dens to try to get rid of them. Then the pet trade emerged as a new threat. Local people collected so many of them to sell that some dens were nearly picked clean. Mason's data showed snake numbers were crashing, and so the pet trade was outlawed.

CHILD: I see a snake coming up.

MONTGOMERY: Today, the snake population is healthy, and Manitoba celebrates its snakes.

[SOUND OF CHILDREN TALKING UNDERNEATH]

The snakes have even become a tourist attraction. In the spring, school buses unload some 400 kids a day as teachers bring their classes to see them.

CHILD: Ooh, he feels scaley.

[SOUND OF CHILDREN TALKING]

MONTGOMERY: Mason says he's proud that his work has not only further scientific research, but also helped change some people's feelings about these common, harmless and fascinating little animals.

MASON: These garter snakes up in Manitoba are really the ambassadors of the reptile world. They're a wild species that's very approachable, and they can teach these kids a lot of lessons about wildlife and how we need to be vigilant about wildlife and about environmental issues. They're the nicest animals you could ever want to meet.

[SOUND OF CHILDREN TALKING]

MONTGOMERY: And he'll be back next year and the year after that as he continues to explore scientific mysteries here, as numerous as the snakes themselves.

[SOUND OF CHILDREN TALKING UNDERNEATH]

In Manitoba, Canada, I'm Sy Montgomery for Living on Earth.

[SOUND OF CHILDREN TALKING]

CURWOOD: Sy Montgomery is author of a children's book about Bob Mason and his snake work. It's called, appropriately enough, "The Snake Scientist."

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Links

The Snake Scientist by Sy Montgomery
Robert Mason's webpage">