Zoo crafts a home for turtles

Bogs: Soggy habitats disappearing in wild mean shrinking population of small reptiles and fewer filters for bay waters.

July 18, 1999|By Joel McCord | Joel McCord,SUN STAFF

To the layman, these little brown turtles with the bright orange flares at the backs of their heads don't seem like much, but they rank up there with Siberian tigers and black rhinos -- and many of them are in Maryland.

One-third of the world's population of bog turtles live in soggy meadows where springs seep out of the ground across the northern halves of Carroll, Baltimore, Harford and Cecil counties. The rest are scattered through Pennsylvania, New Jersey, New York, New England and isolated spots in the Appalachian Mountains in Virginia and North Carolina, says Anthony Wisnieski, reptile curator at the Baltimore Zoo.

Nearly half of Maryland's population disappeared in the last 20 years, as their meadows fell victim to developers and farmers trying to squeeze a little more out of their land and poachers captured them for the exotic pet trade.

The dwindling number of bog turtles does not bode well for the rest of the ecosystem because they are an "indicator species," Wisnieski says.

"If the habitat is no longer suitable for the turtles, that's a big red flag. If the bog is unhealthy, then everything down- stream is unhealthy. And downstream is the Chesapeake Bay."

Bog turtles (Clemmys muhlenbergi) are among the most popular turtles for collectors because of the sculptured motif on their shells and the orange spot on the backs of their heads.

They are protected under state and federal laws, and the Convention on International Trade in Endangered Species forbids commercial trade in them, meaning they are on the same list as Asian and African elephants, pandas, rhinos, sea turtles and whales.

"There are people out there who want to own one of every small thing in the world," says Scott Smith, regional heritage ecologist for Maryland's Department of Natural Resources.

The loss of bog turtles led Wisnieski and others at the zoo and in the DNR and Department of Environment to create an exhibit to explain the importance of the turtle and its habitat, emphasizing the connection to the Chesapeake Bay.

Disappearing habitat

Bogs serve much the same purpose as the marshes of Dorchester County, filtering pollutants from the water. They also slow floodwaters. And the water that seeps from the ground at a cool 55 degrees Fahrenheit is perfect for fish, frogs and other wildlife.

The turtles, which grow to about 4 inches in length, were discovered in Maryland in 1941. At the time, there were 210 freshwater wetlands with bog turtle populations. Now, there are 98.

The wetlands frequently were turned into farm ponds, which get too warm for bog turtles and attract geese and other creatures that eat the vegetation. Other bogs were destroyed when the water table fell as more wells were dug to serve new homes.

Smith describes the turtles in many of the remaining wetlands as "the living dead" because they are reproducing in only 33 of the 98 sites where they have been found. As the size of their habitat is reduced, it becomes more likely that their nests will be disturbed and the number of predators will increase, he says.

Smaller habitats become "predator sponges" that attract the kinds of animals that eat bog turtle eggs, Smith says.

Exhibit with a mission

Zoo officials say they hope to make the bog turtle exhibit, which opens later this summer, a study site as well as a platform from which to preach a save-the-bay message. They plan to put small transmitters on the turtles' shells to track their movements and record temperature data and use DNA testing to study how they reproduce.

The exhibit, the first one in the zoo's Maryland Wilderness section, was created from a pond that a century or so earlier had been a bog.

Two years ago, the pond was covered with parrot feather, a plant native to Brazil, and the acre or so around it was so overgrown no one could see the water.

Zoo staff and volunteers cleared away the non-native vegetation. They added dirt to restore the mucky characteristics of a bog and planted the area with native vegetation.

DNR provided a list of plants that should be around a bog, and the zoo ordered them from a nursery in Pennsylvania that specializes in such things, says Theresa Vetick, a zoo horticulturist.

They planted tussock sedge grass, cardinal flag, mint, swamp azalea, monkey flower and marsh fern.

"We also planted native trees, such as dogwood and swamp magnolia," Vetick says.

David Lee, a bog turtle expert at the North Carolina State Museum of Natural Sciences, provided turtles he had captured nine years ago in Carroll County. Zoo staff trapped meadow voles and other bog mammals to add to the exhibit.

Then they let the whole thing sit.

Now, a neon green scum known as duckweed covers the water. The plants have taken hold and, on close inspection, you can pick out some of the wildlife.

Maintenance crews had to weed out some leftover parrot feather, cattails and Johnson grass early this spring. "But over time, that will take care of itself as the native vegetation gets stronger," Vetick says.

The water trickles downhill, under a bridge and into a tiny stream fed by other springs on the zoo grounds. The stream flows into the Jones Falls, which flows into the Patapsco River. And the Patapsco flows into the Chesapeake Bay.

Pub Date: 7/18/99

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