Nesting time for Wisconsin turtles

Photo courtesy of Ben Vincent/UW-Madison CALS

Jamie Nack, UW-Extension senior wildlife outreach specialist
Department of Forest and Wildlife Ecology
College of Agricultural and Life Sciences

Total time – 3:08

0:14 – Why are there so many turtles on roadways?
1:06 – What is the state of turtle populations?
1:30 – Threats to turtles
2:05 – How to help turtles
2:57 – Lead out


Lorre Kolb: Turtles in Wisconsin. We’re visiting today with Jamie Nack, Extension Senior Wildlife Outreach Specialist, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison/Extension, in the College of Agricultural and Life Sciences, and I’m Lorre Kolb. Jamie, we’ve been seeing some turtles on the road in the past couple weeks, what’s going on?

Jamie Nack: Well, we are just coming to the end of turtle nesting season, and what you’ve been seeing are female turtles traveling great distances to find the perfect site to dig a nest and lay their eggs. Nest making usually occurs around or after dusk. And our smaller turtle species lay about three to five eggs and our larger turtles, like the snapping turtles, will lay anywhere from 30 to 80 eggs. Once those eggs are laid, the female turtles will leave and they will actually hatch on their own unattended by the adults. And a very interesting tidbit about turtles is that their incubation temperature of the eggs will determine the sex of the turtles for most of our Wisconsin species. So that nests with higher incubation temperatures will produce more females and nests with lower temperatures will produce more males. And in our state, eggs incubate any were from 60 to 90 days, depending on the species of turtle.

Lorre Kolb: How are turtle populations doing in our state?

Jamie Nack: Most of the species are doing ok, however, 4 of our 11 turtle species are listed as endangered, threatened or species of special concern. Turtles in general are really slow to mature so it takes a long time for them to rebuild their populations. Blanding turtles, for example, they have to live 17 to 20 years before they reach maturity and can start to breed and replace themselves.

Lorre Kolb: What are some of the threats to Wisconsin turtles?

Jamie Nack: Well, habitat loss and degradation is one of the biggest threats to our turtles. We’ve lost over half of our wetlands since European settlement. We also have urban sprawl and shoreline development that’s permanently removed habitat leaving fewer places for the turtles to nest. At this time of year, automobiles pose a real threat to turtles as they try to cross roads. And another threat is that there’s an increasing number of medium-sized predators that eat turtle eggs. So anything from free roaming cats or dogs, raccoons, skunks, crows, coyotes. In some areas turtle nest predation rates range from 90 to 100 percent.

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