Week 2 began bright and early. By 8am on Monday I was on my way to Queens Creek, where Professor Chambers and I would place the ten modified crab traps. These traps were almost identical to the crab pots we saw sitting on the residential docks along the creek. Ours, however, had tall mesh chimneys protruding from the top. When the terrapins swim in the openings in the sides of the trap, they are unable to find their way back out. Our chimneys allow them to come to the surface for air until we record their presence and release them. We placed the ten traps toward the edge of the creek, attaching them to pieces of wood hammered into the mud so they wouldn’t drift away.
We returned the following morning to check the traps. We weren’t sure if we would find any terrapins in them, since it was only the first day. Much to our surprise, there were seven of them! The first three traps had nothing in them, but trap number four had five terrapins and two other traps each had one. I measured the length, width, and height of each one, then determined the age. I did this by counting the growth rings that are present on every section (scute) of the shell. The terrapins grow faster in the summer than the winter, creating a pattern of alternating sections of lighter and darker shell (similar to the growth rings on trees).
I also recorded the sex of the terrapins. The easiest way to tell the difference between males and females is by looking at their tails. The males have long, wide tails and the females have short, skinny ones. However, sometimes the terrapins have their tails tucked up into their shells, making it difficult to distinguish between the two sexes.
Before releasing the terrapins back into the creek, I marked their shells using a triangular file (don’t worry, it doesn’t hurt them). We assign each individual a number (beginning with one) and use a binary system. The farthest back right scute is assigned a value of 1, the next scute, is 2, then 4, then 8, etc. So, terrapin number 1 has a notch on the first scute, terrapin number 2 has a notch on the second scute, terrapin number three has a notch on both the first and the second scute (because 1+2=3), and so forth.
Many of the terrapins were quiet, retreating into their shells when I picked them up. Others seemed more angry than scared, and tried to scratch their way out of my hands. One bit my hand and held on until I set him on the ground. Luckily their teeth aren’t very sharp; he didn’t even draw any blood.
Occasionally we would come across crabs or fish that had also gotten caught in the traps. I quickly discovered that the best way to get these out was by turning the traps upside-down and letting them fall out, rather than trying to reach in with my hand.
All in all the week went smoothly. We had some beautiful weather and great tides, and found a total of 24 terrapins. Looking forward to continuing with this field work next week!
- Sarah Gilliand