Friday, April 24, 2009

Senioritis

During the final semester of their undergraduate career, students are often afflicted with what is known as senioritis. Symptoms include a general apathy towards their classes, perhaps they are distracted by how their life will soon change or wonder if studying for an exam will do much other than reduce the amount of time available for more pleasant pastimes. I recently realized that the end of my 20th grade of schooling is approaching, and it could be my last before relocating to Florida and dedicating my life full-time to my research.

Soon after this realization, I began to finally experience the onset of my own case of senioritis. The warm weather has only reinforced my longing to cast away the burden of my classes and spend the daylight hours outside, rolling logs to look for salamanders and peering into swamps in the hopes of seeing a serpentine shape parting the water.

I was staring blankly at my computer screen today, trying to muster the willpower to address a class project I’ve been laboring over for the last two months, when I found an excuse to give Sean Graham a call. I knew Sean had recently begun this year’s field season, i.e. collecting cottonmouths in local swamps, and I was hoping I could escape from the office and tag along under the pretense of helping him.

About 30 minutes later we were bumping along the dirt roads of Tuskegee National Forest, headed towards the beaver pond that represent his primary study site. I was last here in the fall for a successful cottonmouth collecting trip at night. Our job today would be somewhat easier, as our plan was to find snakes while there was still daylight.

Snake tongs in hand, I began wading through the marsh, paying particularly close attention to bushes and branches emerging from the water and offering a sheltered spot that still allowed in the sun’s rays. It has only recently become reliably warm, and for many snakes that recently emerged from winter refuges, their priority is to bask in the sunlight and absorb the new warmth. Soon, when the central Alabama heat becomes more consistent and omnipresent, taking advantage of the sun won’t be as important. The snakes will disperse through the swamp, making targeted searches during the day more difficult.

After about an hour, I had yet to see a snake and began to get discouraged that I would find one at all. I consoled myself by listening to some of the frogs calling to attract mates. There weren’t many singing, just a couple of each species really. Perhaps they were just clearing their throats for the oncoming darkness, when most of their breeding would take place. I heard cricket frogs, and gray, bird-voiced, and green tree frogs singing from hidden perches and hiding spots. The one or two solitary calls of the green tree frog were the first I had heard from this species this year, a sign that the time for winter breeding amphibians was coming to a close. In turn, species that sing later in the year, like the green treefrogs, take their place. I heard a great-horned owl hooting in the surrounding woods, also waiting for the cloak of darkness but to begin hunting for unsuspecting prey rather than a mate.

As I explored the depths of a particularly thick and dense patch of bushes, I spotted a small snake loosely coiled around a low-hanging branch. I barely had a chance to peer at the animal for more than a few seconds before it dropped into the water with a faint plunking noise and disappeared from view. I caught only a brief glimpse of its tail as the brown water completely enveloped it. The lack of patterning on the snake and its escape behavior was typical of a plain-bellied water snake, one of the more common water snakes in this habitat.

Disappointed at the escape of this snake before I could even raise my hands, let alone reach it with my tongs, I hoped to have another chance. The dappled light filtered through the trees above, casting shadows around me. As the sun set and the light diminished, each of my steps became more purposeful and deliberate, for fear of stepping on a venomous snake.

As I plodded through the wetland, I investigated any potential hiding spot. I thought the snakes might be looking for areas that were sheltered enough to discourage predation from larger animals but still sufficiently exposed to enjoy the sunlight. Within the swamp, many of the trees sprouted multiple trunks, creating small crooks only about a foot above the water line. It was within one of these crooks that I once again recognized the dark brown shape of a snake. The pale underbelly interspersed with darker bands, along with the dark line running down the side of its broad head, identified the animal as our target species, a cottonmouth. I yelled to Sean, who I hadn’t seen since we had arrived, and he soon appeared out of the swamp to process the snake and take the necessary measurements.

Sean revealed that he had already found a cottonmouth himself. When snakes have recently eaten a meal, they will occasionally regurgitate their prey so that they are better able to escape quickly. He related that the snake he captured had attempted this strategy, revealing a recently ingested amphiuma. Amphiumas, closely related to sirens, are a large, completely aquatic salamander. This one was almost the size of the snake itself.

I soon saw this behavior firsthand. As we emerged from the swamp at the end of our survey, Sean spotted a grotesquely obese ribbon snake slowly slithering along the bank. Although we handled him lightly, the snake began to contort its body and ejected what we immediately identified as a marbled salamander. The salamander looked just as one you might find hiding under a log; it must have been eaten very recently, perhaps within the hour. So that we didn’t cheat the snake out of a meal, Sean gently persuaded it to swallow the salamander again, and placed it in a secluded spot where it could digest in peace. This was a particularly interesting observation, as ribbon snakes are not known to eat that species of salamander.

As we drove out of the forest, we reflected on our good luck (or skill?) on finding three different snake species. On cue, a fourth emerged from the grass alongside the road, a big, beautiful timber rattlesnake. After taking some quick measurements and a blood sample, we admired the strikingly patterned animal as it slithered into the woods. Its camouflage blended perfectly with the leaves that covered the forest floor. True to form, we found this snake in the hardwood forest not far from water. It is within this habitat that the timber rattlesnakes may find some of their favored prey, particularly grey squirrels.

It was great to get away for a few hours this afternoon, but knowing everything that can be found just a short drive away from my office will do little to keep me there tomorrow morning as I catch up on my work.

2 comments:

lisa said...

Hi! Just found your blog through Karen at Rurality, you do some really interesting stuff! I've always enjoyed snakes (Herps in general), and I want to wish you a happy Save the Frogs Day!! :)

David Steen said...

Thanks Lisa.