06/25/2007

Record-Eagle/Douglas Tesner
Turtles bask on a log in the Boardman River, south of Traverse City. A study by herpetologist Leslie Mertz indicates that turtle populations in northern Michigan are declining at a rate that concerns biologists.

Turtle species are on the decline

Half of species found in area are of special concern

BY EMMY PARSONS

eparsons@record-eagle.com

TRAVERSE CITY — Leslie Mertz's first foray into the study of northern Michigan reptiles and amphibians 15 years ago included a population survey that had not been conducted since 1912.

What she discovered was a surprise.

"We found that there was a large decrease in the turtles,” Mertz said. "They had found turtles everywhere, and we found virtually no turtles.”

In fact, four of the eight turtle species found in northern Michigan currently are listed as species of special concern by the state Department of Natural Resources.

"Usually when they are on the species of special concern list, it means that unless we make a concerted effort to help those species, they're headed down the road toward extinction in that state,” Mertz said.

The Blanding's, Wood, Eastern Box and Spotted turtles all have been on the list since the 1990s, and their futures do not look good.

The Spotted turtle's status has been downgraded to threatened, one step closer to endangered, and the four species not on the list appear to be declining, as well.

"There are quite a few turtles that are endangered around the world, or species of special concern in different areas of the world, and it's becoming increasingly common,” Mertz said.

Several factors contribute to the decline of turtle populations. In Michigan, the main cause is sprawl and development, Mertz said.

When new development moves in, the turtle population can be forced out.

"Some of the turtles actually live on land ... so any time we lose habitat that's a big concern,” Mertz said.

Land development also helps predators like raccoons and opossums find turtle breeding grounds because large blocks of forest are separated. Mertz estimates that in recent years turtle egg kill rates have jumped from around 50 percent to 90 percent and above.

"If there's more edge in a forest, it's easier for a raccoon to search that smaller area, and the chances of finding turtle nests are higher,” said Eric Ellis, program manager for the Conservation Resource Alliance's Wildlink Program.

In an effort to preserve turtles and other local species, Wildlink works with developers and property owners of more than 40 acres. If developers can be encouraged to design their properties with the environment in mind, Ellis said, and to avoid areas like wetlands and streams where up to 75 percent of an area's wildlife congregate, development can continue and area species can be preserved.

"It's not an either-or,” Ellis said. "It's not: we can have woods or we can have houses. It's how they're put on the land and then how the surrounding area is managed.”

The loss of any turtle species will have consequences reaching far beyond an interruption in the ecosystem, Mertz said.

"No species other than human beings are stewards of the earth, and every time we fail with just one species and it becomes extinct, a part of our collective human spirit is extinguished too,” Mertz said. "So right here in Michigan, right now, we have this amazing opportunity to step up to our job as stewards of the earth and preserve these four species, not to mention the countless others that are interconnected with them in nature.”