Half-shell habitat at Shollenberger

A handful of humble logs have become the latest tools for education and conservation at Petaluma’s Shollenberger Park, installed in a river channel by the Petaluma Wetlands Alliance as new habitat for an imperiled turtle species.

The logs create new space for the park’s population of western pond turtles to bask in the sun - a required activity for the health of the cold-blooded reptile. Previous debris at the location had recently washed away, reducing the availability of optimal basking locations in the channel and making for fewer sightings of the species, said Bob Dyer, a senior docent with the alliance.

“There used to be lots of basking logs out there. Apparently, over the years, they got lost in the detritus,” he said.

Installed in June, the logs are part of an ongoing effort by the wetlands alliance to enhance and restore the park’s natural habitat. Schollenberger is home to hundreds of species, and some, like the California tiger salamander and the snowy plover, are endangered or under strain, Dyer said.

While the current population of western pond turtles in the wetlands areas around Petaluma is unknown, the long-term survival of the species as a whole has been the subject of heightened concern in recent years. The U.S. Fish and Wildlife Service launched a one-year study in April to determine whether to grant the species heightened federal protection status, following a petition by the nonprofit Center for Biological Diversity that cited population declines of up to 99 percent in some areas.

“They were market-hunted for their meat during the Gold Rush days, and a lot of their wetland habitat was reclaimed for agriculture in the Central Valley, particularly. The rivers and streams were degraded by dams and mining activities, and still are to some extent today,” said Laura Patterson, a biologist with the California Department of Fish and Wildlife, who is studying the species.

The unknown impact of the current drought has created even more uncertainty around the long-term prospects of the species, she said.

If Shollenberger’s native turtle population was lost due to degraded habitat or other pressures, it is unknown when or if the species would return. Current federal and state protections make it illegal to relocate the animals, meaning that the park’s population is largely on its own, Dyer said.

The turtles themselves are the only native freshwater turtle still alive in California, with olive brown or gray hues and a shell that can reach a size of nearly six inches. Human development has eliminated 90 percent of the western pond turtle’s natural habitat across the western United States, according to a recent report by the wildlife service.

“There used to be millions of them,” Dyer said.

The basking logs are located less than one quarter-mile along the right fork of a V-shaped channel that forks close to the park entrance, Dyer said. Their installation in June had rapid results.

“Within two or three days, a couple turtles started showing up on the logs,” he said. “They’re reptiles, so they’re cold blooded. They need to warm up in the sun.”

Creating an opportunity to actually see the turtles in their natural habitat was considered an important goal on its own, Dyer said. Shollenberger Park has hosted thousands of Petaluma third-grade students over the years, part of a Wetlands Alliance-led program to help spark interest in biology and the outdoors.

“We want to give them an appreciation of what’s out there,” he said. “Plus, the kids love turtles.”

Dyer said his group estimates that as many as 15,000 people walk the trails of Shollenberger Park every year.

“Now the public can see these turtles,” Dyer said.

The Petaluma Wetlands Alliance formed in the 1990s to advocate for inclusion of a wetlands component to the then-unbuilt Ellis Creek Water Recycling Facility, which would serve as a discharge area for highly purified wastewater from the plant. Now a committee of the Sonoma County-based Madrone Audubon Society, the group partners with the city to embark on conservation-related studies and work in the Shollenberger, Ellis Creek and Alman Marsh wetlands.

(Contact Eric Gneckow at eric.gneckow@arguscourier.com. On Twitter @Eric_Reports.)