This undergraduate guest blog post has been dispatched by Mark Herr, a junior from Los Angeles who is majoring in Wildlife and Fisheries Science at Penn State. Mark is a member of the Penn State Presidential Leadership Academy, and is interested in continuing on to graduate school to study behavior, ecology, and, of course, reptiles & amphibians:
This past spring I applied for, and with the help of Dr. Langkilde received, a Penn State Discovery Summer Grant to conduct independent research. Initially, I planned to conduct two projects on similar systems. Unfortunately, only the second project (hence the title of this post) resulted in a successful field season. Which isn’t to say that the first project wasn’t valuable – it was perhaps the most valuable research experience I’ve had yet – but its value really lay in lessons learned rather than any publishable results!
Before I explain the project, I want to first give a shout-out to Drs. Langkilde and Sean Graham. Dr. Langkilde managed to let me know that my initially proposed projects were all rather grandiose and unfeasible, while convincing me to keep on firing away with ideas. Eventually, I sent her an idea that we both agreed was novel, and more importantly, possible. Sean went out in the field with me during every day of sampling and made the project possible. This is all the more impressive because he is a post-doc researcher and I am just an undergraduate – which says much both about him and the atmosphere that Dr. Langkilde fosters in her lab.
I don’t want to delve into the specifics of my project idea in California, both because it will bring back the stinging memory of defeat (just joking!) and poison oak rashes so bad that they probably warranted hospital visits – both for Sean and I! Luckily, Sean and Dr. Langkilde had foreseen the fact that all might not go as planned with one of the projects – and so they had suggested that we conduct a second project as insurance. And so it was this “insurance policy” that became my last true hope for some publishable research during the summer break.
My project ran side by side with other work being conducted in Alabama by the Langkilde Lab, which allowed me to help out with other projects when I wasn’t out in the field with Sean collecting snake blood. Yes. Snake blood, and no, this didn’t involve door-to-door salesmen selling cure-alls or primitive rituals by witch doctors.
Sean and I investigated how the stress hormone (corticosterone) concentrations in Cottonmouths (Agkistrodon piscivorus) were related to their anti-predator behavior. Cottonmouths are large bodied, aquatic pit vipers native to the southeastern US. Most importantly, they are abundant. The snakes were honestly even more abundant than I had expected – even though we did have a period where we had trouble finding any, but more on that later.
They are also famous for being aggressive, or, at least that is what the man on the street will say – the consensus among scientists and in peer-reviewed research is that they aren’t anything close to the bloodthirsty mankillers they are made out to be. Cottonmouths do, however, have an extensive suite of anti-predator behaviors. They vibrate their tails (even though they have no rattle), they hiss, they can strike, and they can open their mouth wide in what is called a ‘gape’ in order to convince a possible predator that they aren’t worth the trouble. Actually, this gaping behavior is what gives them their common name – the inside of their mouths has a white lining that is highly visible (especially in their often dark habitats).
The fact that this species has so many different anti-predator behaviors means that I was able to formulate a point system that would rank each individual snake based on how “defensive” it was acting. The procedure was to approach the snake and stand in close (but safe) proximity to it for 15 seconds and then grasp it mid-body with a set of snake tongs for another 15 seconds – all the while taking note of every behavior that the snake exhibited. We would then use a snake tube to restrain the animal and take a blood sample.
As I write this I am laughing out loud at how simple that last sentence makes the blood drawing seem.
The problem, as you might imagine, is that often times (read: every time) the already defensive snake wants nothing more than to avoid slithering up a tight clear plastic tube so that we might get our blood sample safely. For obvious safety reasons, the entire tubing maneuver has to be completed using nothing but a set of snake tongs and a tremendous amount of patience – tubing is the safest way to handle venomous snakes – by far (both for the snakes and the researcher). It’s the industry standard technique.
The process goes something like this:
- Using a pair of snake tongs, the snake is grasped firmly enough at the midbody to prevent the snake from escaping but not so tightly as to injure the animal.
- The tube is maneuvered such that it fits over the snake’s head, and ideally the snake will crawl up the tube such that its body is half inside and half outside the tube, with the snake’s posterior body portion and tail hanging out of the end.
- Swiftly and steadily, the snake is grasped at midbody at the exact point where it hangs out of the tube – with the hand holding the snake firmly grasping both the animal itself and the tube to prevent the snake from either moving further forward or backing out.
Step #2 is sometimes easy, as the snake will cooperate and crawl up the tube as soon as it is able. Usually, though, it is not so easy. More often it would rather keep dodging and moving its head away. Even more often it would rather just strike the tube repeatedly. This process was further complicated by the fact that we were on a tight time schedule –we needed to obtain blood from the snake before its hormone levels had risen significantly (which takes only a few minutes). Did I mention the fact that we were unable to physically touch the snakes until they were in the tube?
We went out during the day and at night searching for snakes, usually spending at least 4-5 hours at a stretch slogging through swamps in waist deep swamp water, and we managed to get to within about 5 snakes of our sample size when we hit a wall. No. More. Snakes. I can’t even remember how many times Sean and I ventured forth without finding even a single snake. It was as though cottonmouths had gone from being the most common snake in the Conecuh National Forest to almost nonexistent. A change in the weather may have been the culprit, but I wasn’t nearly as concerned with the source of the problem as with the prospect that I might not find enough snakes to complete the research.
Luckily, we had a solution. Sean had a location that he knew would guarantee snakes en masse – unfortunately, it was too far away for just a day trip. Our solution was to hit this magical spot on the way back to Pennsylvania on our very last day.
I can’t tell you how nervous I was when we went out that final night.
To set the stage:
- We didn’t have enough snakes. More importantly, we really needed to find a specific subset of snakes, adult males, which are significantly more difficult to locate than adult females or juveniles.
- We absolutely had to leave for Penn State the next morning, making this the absolute last possible time to get enough snakes to complete the project.
- The previous four days hadn’t yielded even a single snake.
- Just for dramatic effect, there was an absolutely MASSIVE electrical storm just prior to our sojourn, shaking the ground and lighting up the sky like a child repeatedly turning the lights on and off inside an otherwise pitch black room.
Well, that night could have shared a title with this post: Redemption in the Deep South. After working from 8:00 pm to 2:00 am, slogging through waist deep (read: sometimes neck deep) blackwater while exhausting our drinkable water, getting lost, and receiving (conservatively, of course) 1,000,000 mosquito bites, we found our 5 snakes. Three of the five were adult males. Our goals were complete. Victory.
I am still in the process of inputting data and running samples, so I can’t yet tell you how stress hormone levels in cottonmouths relate to their behavior. What I can tell you is that working through the trials and tribulations of this summer’s research has made me a better scientist by far. I have many to thank for making this experience possible, but my highest gratitude extends to Tracy Langkilde, Sean Graham, and the cottonmouths of south Alabama. Thanks guys.
Adapted from Mark Herr’s Presidential Leadership Academy Blog