Untitled 5 Untitled 1



History

Riverine Habitat

The wood turtle was listed as a threatened species in 1975. Wood turtles are semi-terrestrial animals (live on land and in water) that are primarily associated with moderate to fast flowing rivers that typically have sand, gravel or coble (rocky) substrates. Their range encompasses all the northern counties in Wisconsin and the southern edge of their range roughly follows a wavering line from Green Bay to Prairie du Chien. The decline in their population is more evident in the southern counties where agriculture and other land uses have degraded water quality in the rivers they occupy or once occupied. They strongly prefer clear (non-turbid) water, which is often stained by tannins (black water), especially in rivers in or that start in northern Wisconsin.

Gestation habitat for wood turtles

Wood turtles are associated with warm, cool and cold water streams. Their terrestrial habitats include lowland hardwood forests, riparian shrub communities (e.g. alder thickets and willow clones) and open meadows, although they will frequently use upland deciduous forest to forage during the summer months. Open canopy (sunny) habitats close to the water are favored by females that are gestating eggs. Wood turtles prefer to nest in sandy soils where vegetation is sparse or non-existent. In the northern half of their range in Wisconsin, especially above Highway 8, most of the riverine habitats flow through forested habitats, limiting the availability of nesting sites.

Conservation

Wood Turtle laying eggs on road shoulder

Until recent years, little work has been done to address the conservation and recovery of this turtle. As a result, many of the nesting areas that were once available to the turtles have become overgrown by brush and trees. While it is not known how many of these nesting sites were originally created by human disturbances, such as from early farming and extensive forest clearing, the fact remains that nesting sites have become far too scarce. This has resulted in wood turtles becoming highly dependent on nesting at bridge crossings, where road corridors afford a narrow but often semi-suitable area of open sunny habitat where females can deposit their eggs, usually in road shoulder sand and gravel. A major consequence of relying on bridge crossings for nesting is significant adult female road mortality. The same can be said about roads that parallel streams and that are close to the water (usually within 200 feet). Sunny roadsides are magnets for nesting turtles, and over time the results can be disastrous from a population perspective, especially for wood turtles. Wood turtles can take 12-15 years to reach maturity. Species that are slow to mature and that are long lived cannot withstand high adult mortality, especially of reproductive females. Some wood turtle populations have been experiencing excessive and detrimental road mortality for decades.

As mentioned in the Introduction Section, wood turtles have also suffered at the hands of humans from over-collecting. A now defunct biological supply business in Oshkosh reported that they once collected hundreds of wood turtles every year, for many years, from Wisconsin’s rivers. Collecting of wood turtles was made illegal when this species was listed as a threatened species in 1975. We know that some poaching of this turtle has occurred even after its protection as a threatened species, and today’s online trading makes poaching more difficult to control.

Nest predation was identified earlier as a serious threat to turtle populations. Of the rare Wisconsin turtles, wood turtles are especially vulnerable to significant nest predation because they are a communal nesting species, meaning that females will congregate at nesting sites, sometime in large numbers. Michigan’s leading wood turtle expert, Dr. James Harding, quoted in 2010, stated,

“Twenty years ago only one of the five nesting sites I monitor annually had predation problems. Today, all five sites experience heavy predation rates, at or approaching 100%. I have not seen a juvenile wood turtle on the rivers I monitor for fifteen years.”

Nest predation is likely amplified by the fact that so many wood turtles nest along roads, making nest detection by predators especially easy.

To help address the issues of adult female road mortality and nest predation, a program was initiated in 2011 to restore overgrown nest sites and create new nesting sites. These restored and created sites are located away from roads. The goal is to draw female turtles away from roads and provide them with larger sites where at least some nesting success can be expected. Some of the newly restored and created nesting sites are equipped with predator excluders to help improve nesting success. There is a huge need to get landowners who own land along occupied wood turtle rivers and streams involved in nest site creation and/or turtle nest protection. Serious landowners are encouraged to contact the director of this organization for free information on this subject at racs@tds.net.

You can also help with this species conservation by providing Turtles For Tomorrow with your observations of rare turtles and their nesting sites.

Untitled 2
Home | Governing Board | Current Projects | Donate | Highlights | Featured Species | Resources | Contact Us