Corvallis’ Own Snake Scientist Talks Snake Sex, and More

  Integrative Biology Professor Bob Mason might just know everything about the intimate life of the garter snake. For over three decades, Mason led the way in unraveling some of the mysteries on snakes, pheromones, and what makes a snake sexy.  

The Mason Lab at Oregon State University is primarily focused on reproductive biology and a subspecialty of chemical ecology. Much of his research focuses on the red-sided garter snake, who he sees as a model species paving the way to research which is relevant to other species. 

Mason was the first scientist to identify, isolate, and synthesize a reptile pheromone. This pheromone is the one that the female red-sided garter snake releases while seeking a mate.  

“No one had ever found a pheromone in any kind of reptile before,” says Mason. This discovery involved “hard work and also some luck. It turned out we were the first to identify and isolate it chemically. Then we were able to make it in a lab. When we presented it to the snakes, they liked it.” 

In February, 2020, The American Association for the Advancement of Science honored Mason with the distinction of AAAS Fellow at their annual conference. He was one of 443 scientists selected in 2019 for their “extraordinary achievements across disciplines” in areas like teaching, publishing research, and advancing public understanding of science.  

Spring Snake Emergence and Mating

For over 30 years, Mason visited Narcisse in Manitoba, Canada every spring to conduct field research. Due to COVID-19, the Canadian-US border is closed. This is the first spring that he stayed home and missed the snake’s emergence.  

Garter snakes are common in many places including the Corvallis area. Mason says that locally, they are out for most of the year due to the milder climate. People sometimes ask Mason why he travels to Canada to study garter snakes when there are so many locally. 

“If you study snake reproduction,” explains Mason, “you have to go where a lot of snakes are reproducing.” 

Mason describes the emergence from the Narcisse dens as “the largest concentration of snakes in the world.” 

Because of the unique climate and geology of Manitoba, more than 70,000 garter snakes emerge from these 4 dens each spring to mate, feed, and disperse to their feeding grounds before they retreat back into their dens for the long winter. Mason explains that the winter in Manitoba can last eight months of the year. 

Canada’s garter snakes are the most northerly living reptiles, some even approach the arctic circle. Since snakes are cold blooded animals, they spend their winters clustered in underground caves and sinkholes below the frostline.  

They are not technically hibernating, explains Mason. Instead, reptiles brumate. During brumation, snakes move very slowly, if at all – but they only lose a small amount of body weight compared to mammals during hibernation. According to Mason, a snake den can fit close to 70,000 snakes in a space similar in size to the average living room.  

In late April, May, and June, the snakes emerge. First, the males all come out to the surface. Mason describes the sight of the males emerging like seeing “a sea of living spaghetti.”  

Although garter snakes are normally timid, the snakes that emerge in Narcisse are singularly focused on mating, so they pretty much ignore their human visitors and observers. Mason says a snake will easily slither over a person as if they were a log.  

Once the males are all out, the females start to emerge little by little. At any moment in time in the spring breeding season, there are at least 100 males to every female. Female garter snakes are larger than the males, and the males find them through their scent or pheromone. The female chooses who she mates with, but exactly how and why she chooses them is not yet known. 

That pheromone is the one that Mason identified, isolated, and synthesized. Mason says the scent cues are very important to snakes – even to the exclusion of other cues, like visuals. For example, Mason says, the male would try to mate with just about anything including a sheet of paper if it has the correct pheromones.  

It takes weeks for all the females to come out and mate. Each year people visit the Narcisse Snake Dens to witness nature in action. The remote town of Narcisse is normally small, but each spring, tourists, researchers, and snakes drastically increase the local population. 

Research Impacted by COVID-19 

Mason says that over the years, his network of former students and collaborators has grown. In a typical spring in Narcisse, a dozen people from six or seven universities may all be “working on different aspects of the snake story.”  

“The snakes are fine,” says Mason. “We’ve tried to look for the silver lining.” 

The silver lining for the moment is that Mason and his former student Deborah Lutterschmidt, now a professor at University of California, Irvine, are able to further their research. One of their research lines looks at how stress hormones may impact the snake’s reproduction. Normally, the snakes have a large human audience during their emergence and mating season. With the Narcisse observation dens closed to visitors, the snakes are alone for the first time in many years. Canadian collaborators have collected small blood samples so Lutterschmidt can measure the hormones.  

“Even though we’re not up there, we are still trying to do some science and make some lemonade out of these lemons we got served up,” says Mason. 

Implications of the Research 

Mason says he finds snakes fascinating on their own, but there are deeper reasons why biologists study snakes. When looking at something as complex as pheromones, it helps to study a simpler model species. Other scientists can build on that work by studying more evolved organisms. 

“They are a little bit simpler because they are more ancestral,” explains Mason. “So, the things that we can understand and learn in reptiles often lead to things that have implications down the line in other more derived animals like mammals and even humans.” 

For example, it is easier to observe the effects of pheromones on snakes because their sexual responses are simpler – the visual and social cues are not as important as scent. Visual, auditory, and social cues are more important to mammals like humans or even dogs or horses, making it more difficult to identify, isolate, and study pheromones.  

However, the importance of pheromones has been observed in mammals. Mason provided an example that may feel familiar to anyone with a dog. When a person walks a dog, they often notice that the dog prefers to pee a little in multiple locations – on a bush, a telephone poll, and perhaps a fire hydrant.  

According to Mason, the dog is leaving a trail of pheromones that provides information to other dogs. With just a sniff or two, other dogs may learn that the urine was left by a female called Fifi who is in heat and lives nearby. 

“There’s really exquisite communication going on there,” says Mason. 

There is still much to learn about the power of pheromones – in snakes, plants, mammals, and humans. Mason says that other scientists’ research with infants and their mothers makes a strong case for the existence of human pheromones. For example, a researcher at University of Wolverhampton published research about how newborn infants and their mothers recognize each other by scent or chemical communication. 

Mason noted one practical application of using snake pheromones. In Manitoba, snakes will cross the road and many will get run over. The Narcisse Snake Mortality Advisory Group forged a partnership with businesses, organizations, and volunteers installing a series of small tunnels under the highway for the migrating snakes. Mason and his students experimented with using pheromones as a chemical trail to encourage snakes to use the tunnels. 

The tunnels were a success, drastically reducing the number of snakes killed each year. 

How Snakes Benefit Humans 

“You know you are in a healthy place if you see snakes,” says Mason. Not only does the presence of snakes indicate a healthy ecosystem, but garter snakes are gentle and harmless to humans.  

Garter snakes are also timid around humans. The worst they are likely to do is “schweeze” an unpleasantly scented excretion from their backside if picked up. Mason explains that this isn’t feces, but a defensive mechanism snakes use to get predators to spit them out so they can escape.  

Garter snakes also provide natural, safe pest control benefits to local gardeners.  

“Lots of Oregonians are gardeners,” says Mason. “Most love to hate slugs. Slugs are like chocolate candy to a garter snake!” 

Mason likes to describe the garter snake as an “ambassador to the reptile world.” He believes fear of snakes is a learned behavior. He has observed children who first encounter a garter snake reaching out to touch it and pick it up – until their parents warn them about the dangers of potentially venomous snakes.  

“It’s not instinctive that we have a fear of snakes,” says Mason. “If that were true, we would all be that way. A lot of kids love to play with snakes.” 

He wishes that more people who dislike snakes would learn to leave them alone and regard them with a healthy respect. It makes him sad to see people who hurt or kill harmless snakes like a garter snake rather than simply leave them be. 

As research subjects, snakes offer biologists and other scientists a model species for research which could serve as a foundation to other research that could benefit humans in the future. As vertebrates, snakes are more like us than they are different biologically. Like us, they share many similar organs, blood, and hormones.  

Beyond 15 Minutes: Mason’s Brush with Pop Culture 

Not every scientist has the opportunity to inspire both a B-grade film and a meme. Mason recalled a conversation with a German reporter in the mid-2000s. She asked him how he felt about being the inspiration behind the 2006 film “Snakes on a Plane,” then informed him that the plot’s concept was inspired by his research into snake pheromones.  

For those unfamiliar with the film, the plot of “Snakes on a Plane” involved an organized crime boss using a cargo-load full of venomous snakes on a commercial airplane as an assassination weapon. At a specified time, a pheromone would be released that compelled the snakes to attack the passengers.  

Mason says the screenwriters got one thing right – snakes are motivated by pheromones in surprising ways. However, these pheromones are very specific, so there isn’t just one that could be used to control multiple species or that would cause such behavior.  

Mason says that as far as his students are concerned, “There’s nothing I could ever do scientifically that could match being on The Sopranos.”  

Over the years, Mason has appeared as a guest on multiple nature documentary shows. The Sopranos season 3, episode 9 (originally released in 2001) featured a clip of one of those documentaries while two main characters – Tony and Pauly – discussed their opinions on the mating habits of snakes.  

B-grade films and mobster dramas aside, Mason is most proud of a children’s book covering his field research in Manitoba, Canada. Thanks to this book, Mason is known to children all over the nation as “The Snake Scientist.”  

Snake Scientist Inspires Interest in STEM 

Nature writer Sy Montgomery and photographer Nic Bishop spent a season in the field with Mason researching their book and taking photographs. Mason admitted he was a little unsure when Montgomery first reached out to him.  

“It isn’t like we are going to downtown Toronto. As I always said, it’s not the last truck stop on earth, but it is the second to the last.” 

The area is somewhat remote, with limited conveniences such as easy internet access and indoor flush plumbing.  

“My students are pretty appalled, because they find out there are places on earth where there is no cell coverage,” jokes Mason. “Which I love, because it’s great to get away from things.” 

According to Mason, Montgomery and Bishop were great additions to the research team that season. “The Snake Scientist” tells the story of the red-sided garter snake and Mason’s research. 

“Between Sy’s writing and Nic’s pictures, it was a real success!” Mason exclaimed. 

The book won several awards, including Booklist Editor’s Choice, Booklist Top Ten Youth Sciences Books, and an International Reading Association Award. So far, Montgomery published over 28 books for children and adults, as well as a National Geographic screenplay.  

Mason said he still receives letters and email messages from children, parents, and teachers about “The Snake Scientist.” 

“I love to brag about that book,” says Mason. “It helps get kids excited about science, so that is really nice.” 

Mason says his own parents, particularly his mother, encouraged his interest in science and nature when he was a child. He would bring home snakes and critters he caught. Instead of saying, “get that snake out of my washing machine,” Mason’s mother allowed him to keep the animal in an aquarium for a little while, then instructed him to return it to the location where he captured it.  

He wasn’t sure to what extent that parental encouragement led him to his research, since he didn’t set out to study snakes. As a graduate student at the University of Texas, he joined the research lab of a scientists who studied reptile reproduction. One of his advisor’s projects involved garter snakes, and that solidified his path.  

The book “The Snake Scientist” by Sy Montgomery is available to borrow from the Corvallis-Benton County Library.  

By Samantha Sied