Painted Turtle Studies at the Larsen Sanctuary

by Dr. Tony Pappantoniou
Associate Professor of Biology
Housatonic Community College

Brittany Boroski, Diana Quiroga and Professor Anthony Pappantoniou, from left, examining turtle traps in Farm Pond.

Starting with summer 2010, Housatonic Community College students have engaged in a variety of field studies at Connecticut Audubon Society’s Roy and Margot Larsen Wildlife Sanctuary in Fairfield. The students are volunteers chosen from my general biology class. I generally have four to six volunteers every summer and our field season starts in June and goes through August.

Initial studies centered on a survey of the fish found in the sanctuary streams. After two summers, I decided to refocus the study on the turtles of the Farm Pond, with a goal of eventually charting growth rates and estimating population size.

There are two main species of turtles in the pond, the painted turtle, Chrysemys picta, and the common snapping turtle, Chelydra serpentina. We have also collected a few red-eared sliders, Trachemys scripta elegans. The sliders are not native to the area and were most likely pets released into the pond. I decided on the painted turtle population, as the snapping turtles were too dangerous to handle on a regular basis.

What We Do: We set live traps for the turtles each Thursday of the study period. We come back Friday morning and check the traps. Any painted turtles that are collected are treated humanely, data is collected quickly and the individuals are released back into the Farm Pond.

Professor Pappantoniou examines a painted turtle with two students, Suji Im and Justin Tracey.

The Data We Collect: Each turtle is weighed, the length of upper shell (carapace) is measured, and its gender determined as is the age of the turtle. Age is determined by counting the rings on the scales of the plastron (lower shell). Determining the sex of the painted turtles is not difficult. We look at the tails and claws of the turtles. The males have much longer claws and a longer tail. After comparing a few individual turtles, students rapidly learn how to sex the turtles.

We use a dietary scale to weigh the turtles and calipers to measure the length of the carapace. Students divide the tasks among themselves, with one student recording the data. When all the data is collected, each turtle is marked by filing notches into the marginal scutes (scales). We use a system of marking the scutes so that individuals can be recognized if they are re-caught. Notching the scutes does not cause the turtles any discomfort. The scutes do not have nerve endings that could lead to pain sensations.

What We Found: We have collected and marked 67 individuals, some of which have been collected several times over during the two years of the study. To date, our youngest individual was a one-year-old. This turtle was 40 millimeters and weighed 53 grams (about 1.6 inches and a little under 2 ounces). The oldest female was eight years old and the oldest male was 10 years old. Our largest male weighed in at 598 grams and our largest female weighed 478 grams (both in excess of one pound).

Measuring the length of the carapace.

In terms of length, our largest specimen was a 156 millimeter male (over six inches long). As we catch the same individuals over again from one year to another, we will be able to chart growth and ultimately estimate the size of the Painted Turtle population.

Studies such as these are long-term studies, sometimes lasting several years or even decades. We hope to be able to continue our studies over the next several summers. Students find these hands-on experiences very interesting. They give students a sense of the type of real life data that biologists collect and how they develop a picture of an animal population.

I would like to thank the staff and administration of Connecticut Audubon Society for welcoming us back to the Larsen Sanctuary and allowing us to use this valuable natural resource as a learning environment.

Dr. Tony Pappantoniou
Associate Professor of Biology
Housatonic Community College
Bridgeport, CT 06604
apappantoniou@hcc.commnet.edu