Target Species: Alligator Snapping Turtle (Macrochelys temminckii)
I’m a little embarrassed that it has taken me all the way into May to check off the first species of 2020 from my list of biodiversity goals, but it was a good one – an ancient leviathan dwelling in the depths of a murky stream meandering through a mature hardwood forest – the old loggerhead – the alligator snapping Turtle (Macrochelys temminckii)
This story begins in January, with a meeting at my Alma Mater – Stephen F. Austin State University (SFA) in Nacogdoches, Texas. I met with Dr. Chris Schalk, a herpetologist and ecologist with the Arthur Temple School of Forestry, the department where I obtained my undergrad. We discussed ways that we may collaborate on topics like road ecology and reducing impacts to wildlife from transportation projects. I immediately liked Chris, and found him a like-minded individual in many respects.
In the following months we touched base from time to time, and in one of our conversations he mentioned the research being carried out by one of his graduate students, David Rosenbaum. Chris recounted the start of their field season, during which they captured numerous large alligator snapping turtles. And much to my delight, he invited me to join them on a future outing.
It may not be surprising to the followers of my blog, but this sort of thing is right up my alley. One of my most memorable jobs was when I worked a summer as a field tech on an American alligator research project. Capturing these ancient reptiles was equal parts thrilling, interesting, and rewarding. The idea to relive that in some small part was an opportunity too good to pass up.
So in late May I met up with David, and field techs Laura and John Michael. Also along for the day was my good friend and frequent adventure companion, James Childress. After some brief (socially distant) introductions, we were on our way to the first study site, a tributary to the Angelina River deep in a remote hardwood bottom.
Blooming American elderberry lined the banks here, and the boughs of ancient River Birches and American elms reached out over the water. From high in the canopy the buzzy trill of a Northern Parula rang out. A suite of other songbirds also made their presence known, including a Prothonotary Warbler, Hooded Warbler, Swainson’s Warbler, Yellow-throated Warbler, Red-eyed Vireo, Summer Tanager, and Acadian Flycatcher. In the distance we could hear the cackle of a Pileated Woodpecker and the croak of a Yellow-billed Cuckoo. It was immediately clear that this site was rich in biodiversity on land and air. We would soon realized it was equally diverse beneath the water’s surface.
For the first year of their study, David and Chris are replicating a survey performed twenty years ago. When I added the alligator snapping turtle to my list of biodiversity targets, I knew that I would have to think outside the box if I had any hope of photographing one. This is not a species that one can expect to find by conventional means. They spend virtually their entire lives at the bottom of streams, rivers, lakes, and deep swamps. They can stay submerged for nearly an hour, and the only time they can be expected to seen on land are when the females leave the water to lay their eggs, and the rare occasion when an individual disperses to a new water body. In short, I knew if I wanted to see one, it would have to be trapped.
Fortunately, that was exactly what David, Laura, and John Michael were doing. They use special partially submerged traps that allow for the turtles to be captured alive and unharmed, and check the traps daily once they’ve been deployed. I was joining them for the third day of trapping effort at this particular site, which had several traps spaced out along this meandering forest stream. The first day trapping here they caught six individuals, however the previous day they had caught none, so no one really knew what to expect.
The first trap we checked was empty, save a decent diversity of riverine fishes. The second did have a turtle. It was an interesting species, but not the one we were looking for. Razorback musk turtles occupy similar habitats to alligator snapping turtles, and have been the subject of previous studies by SFA. I didn’t photograph our first turtle of the day, but was certainly happy to see it.
Soon after the three researchers sank into the chest deep water at the third site, I heard David call out, “We’ve got something big in this one!” It was a special thing, seeing him reach into the depths and pull out this massive, prehistoric-looking beast. In that moment I thought of the fascinating ecology of these streams. Beneath the water exists a diverse world that is unknown and unseen by most.
They pulled the massive turtle to the shore so that they may collect a variety of data, including morphological measurements, images, and blood and tissue samples. It was determined to be an old female weighing in at nearly forty pounds. We knew she was old, based on her smooth carapace. When young, they have three raised ridges with scutes that form triangular peaks. After years and years of wandering under woody debris lodged in the stream bottom, the shell gradually wears down until, in very old individuals it becomes essentially smooth.
We knew she was old, but we had no idea how old. Large turtles can live a very long time. When collecting those previously mentioned data, David and his team noted that the turtle had a distinctive notch in her shell. It turned out that she had been captured during the original survey, 20 years ago. We aren’t sure how large she was at that time, but that information should be available, and I’m very interested to find out!
David’s study will be looking at a variety of aspects related to the ecology of alligator snapping turtles in eastern Texas. One aspect of his research is very similar to my own master’s thesis – using presence/absence data to determine important variables that can predict for the species’ occurrence. I really enjoyed chatting with David about his project, and it brought me back to a time when this sort of thing played a much larger role in my life.
The research being carried out by David and Chris is important. Alligator snapping turtles populations have declined dramatically, and they are now uncommon or rare throughout much of their range. Factors influencing this decline include a loss of high quality habitat and over-harvest for its meat, which has long been considered a delicacy. As a result, they are now protected in many states where they occur, including Texas. This protected status has not stopped illegal poaching, however, and many animals are still taken this way, or caught on trotlines set callously in their habitat. Once hooked on these lines, the turtles suffer a slow, agonizing death.
When initially captured or threatened, the loggerhead generally opens its mouth wide, and will snap at anything that approaches too close to its head. Believe me when I say, this is a very effective intimidation tactic. Those jaws slammed shut with bone-crushing force. Those powerful jaws play a very important role in capturing prey in their murky aquatic habitats. Alligator snapping turtles have lingual lures – specially adapted tongues shaped like worms that the turtles wriggle about while waiting motionless with their jaws wide open. When some unsuspecting fish moves into to capture this false worm, the snapper’s mouth slams shut with blinding speed and crushing force.
As impressive as this gaping threat display was, I was really happy to capture images of the gator turtle with her mouth closed, in a more natural looking pose. We spent a few minutes photographing and admiring this incredible animal. We then set her near the stream’s edge, and walked as she slowly made her way back into the water and disappeared into the deep.
Spending time with this modern-day dinosaur was an incredible experience, and I was very grateful for the opportunity to get to know David, Laura, and John Michael and learn more about the important work they’re doing. It made me nostalgic for my days as a field biologist, but fortunately my current position does provide opportunities to be involved in research, specifically aimed at conservation of wildlife and plant communities related to transportation activities. I hope to join David and crew again in the field at some point, and very much look forward to what they learn about the ecology and natural history of this keystone species.