Turtle Population Apparently Threatened By Urban Sprawl, Traffic

August 06, 1998

CHAMPAIGN, Ill. -- Yellow and black blotches and a peaceful demeanor make Blanding's turtles (Emydoidea blandingii) easy to identify. Finding them, however, is getting more difficult, especially in two Chicago-area forest preserves, because of shrinking numbers.

Populations, which likely intermingled in the past, have been driven apart by urban sprawl and traffic on suburban roadways that now separate them, says Cory S. Rubin, a doctoral student in the University of Illinois department of natural resources and environmental sciences (NRES).

Rubin has been searching the West Chicago Prairie and Pratts Wayne Woods forest preserves, which are eight miles apart in Du Page County, west of Chicago. He has found just over 50 adult turtles.

He reported his preliminary findings Aug. 6 at the Ecological Society of America annual meeting in Baltimore. The populations are genetically depauperate -- not completing normal development -- when compared with larger populations throughout the turtles' range, potentially leading to inbreeding depression, loss of evolutionary advancement and ultimately threatening their existence.

Rubin captures the turtles, attaches radio transmitters before setting them free, and analyzes blood samples using gene-amplification techniques known as RAPD (randomly amplified polymorphic DNA) and PCR (polymerase chain reaction). So far, he said, he has found a near-100 percent loss of hatchlings as a result of predation and apparent lack of turtle migration between the two reserves.

"Blanding's turtles is a great species for educational purposes," Rubin said. "They don't bite. They are extremely passive. Everyone seems to like turtles, and everyone who sees me looking for them always has a turtle story for me."

The turtles live in vegetation near freshwater lakes, ponds and marshes. They are found in small numbers near the Great Lakes, west to Nebraska, Iowa and northeastern Missouri. Others are found in Maine, Massachusetts, New Hampshire, New York and Nova Scotia. Rubin's findings suggest that the Nova Scotia population, where they are a threatened species, are genetically separate from those in the Midwest, implying special conservation concerns.

"It's the population in Illinois that is showing the most potential for population isolation and loss," Rubin said. "The turtles once were common throughout the northern two-thirds of Illinois, but now their numbers are scarce and restricted to the northernmost region."

Rubin's research -- supported by the Du Page County Forest Preserve, Chicago's Lincoln Park Zoo and NRES -- eventually will result in detailed reports on the turtles' demographics and genetic comparisons with the turtles' cousins in the Sandhill Wildlife Area in Wisconsin, the E.S. George Reserve in Michigan and Kejimkujik National Park in Nova Scotia.

The ultimate conservation question, Rubin said, is which other populations have gene pools that would easily mix with those in Illinois to maintain healthy numbers of the Blanding's turtles.
-end-


University of Illinois at Urbana-Champaign

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