Study dials up western pond turtles – Herp Digest

SF Gate.com, Carolyn Jones, 7/31/13

Turtle No. 13 is pretty much like western pond turtles everywhere. The greenish, speckled reptile likes to wallow in the mud, bask on old logs and munch on dragonfly larvae.

But then there's the 8-inch antenna on her back.

She and each of her 23 cohorts in a secluded Mount Diablo pond are affixed with radio transmitters on their shells so scientists can track their every poky, mud-filled move.

The turtles are oblivious to their high-tech accessory, but the information they provide has given biologists a glimpse into one of the most rare, and mysterious, reptiles.

"This is the holy grail for turtles," said David "Doc Quack" Riensche, an East Bay Regional Park District biologist who's been conducting the study for three years.

"How far do they go? Where do they winter? What kind of vegetation do they like? We're trying to find these answers so we can learn what's the best way to save these guys."

Western pond turtles, the state's only native turtle, are a "species of special concern," according to the California Department of Fish and Wildlife, and are declining rapidly throughout the West. Once common in creeks and ponds in the Bay Area, the distinctive reptile is now fighting for survival.

The main culprits, aside from habitat loss, are nonnative bullfrogs, which eat the turtle eggs, and invasive red-eared slider turtles, which carry diseases and outcompete the western pond turtle for food and shelter.

The result is that few sizable colonies of pond turtles exist. When embarking on his study, Riensche scoured Alameda and Contra Costa counties for the elusive turtle and found almost none.

Then he stumbled across a 1-acre, spring-fed cattle pond in the eastern foothills of Mount Diablo outside Clayton.

There, he found more than 75 western pond turtles frolicking in the muck.

"It was like the Fertile Crescent," he said. "I was ecstatic."

During breeding season, Riensche and a crew of volunteers - including, sometimes, his wife and kids - trek to the pond daily to check on their subjects.

They catch a few turtles to weigh, measure and inspect for raccoon attacks, then they circle the pond with a wire antenna that resembles TV rabbit ears.

The antenna is affixed to a radio frequency tuner, which volunteers can adjust to locate individual turtles. It beeps when it receives a signal.

Fortunately, turtles don't go very far. Most are lounging in the mud or snoozing on a log. But when laying eggs, females can wander 100 yards or so from the pond - a migration that's critical to understanding how the turtle successfully breeds.

With the help of the antennas, scientists have learned the preferred nesting sites are sunny areas with grass about 1 1/2 feet high covering about 85 percent of the ground. There, the female turtle digs a small hole, deposits her eggs, buries them and lets them incubate in the warmth for two months or so.

Scientists also learned that turtles hibernate underwater for several months in the winter, clustered in the shallow end of the pond.

The information Riensche and his crew gather is sent to state Fish and Wildlife scientists, who use it to create a conservation plan.

Turtle tracking is not for the impatient. Volunteers spend many long hours by the pond with the antenna, waiting for one of nature's more relaxed creatures to do something interesting.

Maggie Clark, a bookkeeper from Lafayette, said she doesn't mind. In fact, it's sort of soothing, she said.

"Any little part I can do," she said. "This is a huge metropolitan area, and I think it's important we try to save as much as we can."

Richard Kaufmann of Oakland, a retired Lake Merritt naturalist, said he considers turtle tracking "payback."

"If you look at all the resources people have taken from the planet - wildlife has had to adapt. Some have, and some are having a harder time," he said. "I see this as a little return for what we've taken."

Turtle study

To volunteer on the western pond turtle study, e-mail David Riensche at docquack@ebparks or call (510) 544-2319. For more information, go to www.ebparks.org/getinvolved/volunteer/quack#how.