DuPage using DNA testing to save Blanding's turtles

Genetic testing is being used to help the DuPage County Forest Preserve District save an endangered species of turtles.

The district has been pursuing a Blanding's turtle recovery program since 1996 to try to rebuild the reptile's numbers in DuPage that includes providing a safe place for turtle eggs to hatch.

In recent years, officials have been collecting DNA samples from hatchlings to measure the success of the recovery program and determine where the Blanding's turtle population is heading in DuPage's forest preserves.

"When you are talking about an endangered population with smaller numbers, you are concerned about the genetic health of that population," said Dan Thompson, a district ecologist. "How diverse is it? Have we lost a lot of genetic diversity? This is what we're trying to monitor."

Blanding's turtles are an endangered species in Illinois because of disappearing wetland habitats. People also illegally collect the animals, which are known for their vibrant yellow markings.

The turtles, which can live more than 70 years, don't start breeding until they are in their teens.

In the 1990s, district ecologists noticed they were mostly finding mature Blanding's turtles and weren't seeing many young ones.

"For some reason, the next generation was not being produced to carry on," Thompson said.

When they discovered that predators were raiding turtle nests and snatching the eggs, district naturalists decided to intervene.

They began tracking turtle births in 1996 and eventually started attaching transmitters to females.

Now when female turtles are ready to start laying eggs, usually in June, naturalists take those turtles to Willowbrook Wildlife Center so they can nest at the Glen Ellyn facility.

Once a turtle lays her eggs, she's released and her eggs are placed in an incubator.

"We're bypassing the predation rate by bringing the eggs in before the females nest," Thompson said. "Because we know if we let them nest (in the wild), it's almost a guarantee those eggs are going to be eaten, and there won't be any offspring successfully hatching to start rebuilding these populations."

This year, there were 239 hatchlings.

About half of the hatchlings were released during the fall. The rest will be reared for up to two years at Willowbrook and other sites, including Wheaton Park District's Cosley Zoo and Hickory Knolls Discovery Center in St. Charles.

"We have a strong partnership with a number of local agencies," Thompson said. "To bring a species back from the brink takes a lot of effort. This is something that would be very challenging for us to do on our own."

While there's no estimate as to how many Blanding's turtles there are in DuPage, officials are seeing positive signs that the population is starting to build.

For example, there was offspring this year from three female turtles that were hatched years ago as part of the program.

"That's telling us we are making a difference," Thompson said.

Meanwhile, the DNA testing will help officials determine where the turtle population is heading.

Thompson said genetic diversity is critical for the turtle population to survive emerging diseases and other changes.

"The more diverse you are, the more likely you are going to have resistant individuals who can withstand some of those changes," he said.

Officials still are in the process of collecting the data. They don't yet know if there's anything in the genetic makeup of the turtles that leaves them vulnerable.

Once the information is gathered and analyzed, it will be valuable in developing a strategy to make the population more genetically diverse, he said.