Sampling for Wood Turtles


Wood Turtles' shells come in a variety of colors and patterns. - Houston Chandler

The Orianne Society spends a significant amount of time working on Wood Turtles in Vermont as part of the Great Northern Forest initiative. But did you know that Wood Turtles can be found in approximately 15 other states and in some parts of southeastern Canada? Despite this relatively large range, Wood Turtles are listed as Endangered by the IUCN and have already experienced population declines throughout most of their range, making them one of the rarest freshwater turtles in North America. Many threats still remain for extant populations, leading to large scale research and monitoring efforts spear headed by the Northeast Wood Turtle Working Group ( I recently assisted Jordan Gray with a Wood Turtle survey that is part of this larger effort to conserve this species.

Despite being relatively large turtles, Wood Turtles do a remarkable job blending into the rocks on the bottom of a stream – Houston Chandler

During winter and spring, Wood Turtles are tied to various water bodies that serve as refugia from lethal winter temperatures. Surveying in and around these water bodies is often the most effective way to monitor the status of Wood Turtle populations. In this case, we were conducting the 2nd spring survey of an approximately 1.5 km stream reach. The goal of our survey was to catch as many turtles as possible, marking all individuals and collecting morphometric data. These data will eventually be used to estimate the number of turtles that call this section of stream home and then to ascertain whether or not the population is stable over time. As with all turtles, these are challenging objectives to accomplish because of the long-lived nature of the animals, but this population was first studied almost 10 years ago now. A promising beginning to any turtle research project.

Good calipers are key tools for any turtle biologist – Houston Chandler

Ideal weather — clear skies with temperatures in the 60s — meant we were unlikely to have a poor survey. Over the course of a few hours we managed to find 13 Wood Turtles. These individuals were a combination of turtles that had been previously caught and a handful of turtles that were brand new to the study. It is always exciting to catch new adult females! For each individual that we captured, we recorded whether or not it had been previously captured, collected some routine measurements (length, weight, etc.), noted any abnormalities on the shell, and added a notch identifier to the marginal scutes, if needed. All individuals were then released at their point of capture to carry on with their lives.

I am generally amazed when conducting mark-recapture surveys how individuals can go ‘missing’ for several years only to turn up in more or less the same locations where they were originally marked. One of the turtles that we encountered was originally marked almost 10 years ago and had not been encountered since then, despite many visits to this same stretch of stream. Other highlights from the day’s survey included a sub-adult turtle, indicating relatively recent recruitment into the population, and some absolutely stunning examples of what makes Wood Turtles so visually spectacular. The skin behind the legs is strikingly orange in the right light.

Injuries are relatively common in many freshwater turtle populations. This large male was missing one of his front feet but appeared to be mostly unaffected. – Houston Chandler

Ultimately, the data collected on this and other similar surveys will be used to benefit the conservation of these incredible animals. The data will be combined with other survey data to conduct regional analyses of Wood Turtle populations as part of a long-term strategic objective of the Northeast Wood Turtle Working Group. These efforts are critical to ensuring that threats from habitat loss, collection, and road mortality do not continue to push Wood Turtles towards extinction.

The author processing a captured Wood Turtle – Jordan Gray