Oakland Zoo head-start program nurtures turtles

Oakland Tribune, Sep 29, 2008 by Angela Hill

OAKLAND -- Smaller than a quarter at birth, slower than frozen molasses, unable to fend off nonnative predators and competitors to save their lives, they're Western pond turtles -- California's only native aquatic turtle species -- and their numbers are dwindling by the day.

Once thriving in the millions from Mexico to Canada, they are now extinct in British Columbia, critically endangered in Washington state and considered a "species of special concern" by the California Department of Fish and Game, researchers say.

So the sight of six wee baby pond turtles paddling around on Thursday in three shallow, water-filled plastic tubs in a back workroom at the Oakland Zoo is a beacon of hope to scientists. It's the early result of a new captive-breeding program -- the first of its kind for the species -- developed by a professor at Sonoma State University in conjunction with the Oakland and San Francisco zoos to give the little guys a head start in life and rebuild their population.

"We decided we needed to do something before it was too late," said Margaret Rousser, lead keeper of Oakland's children's zoo, where the six turtles are being raised. More will arrive in the next week or so as they continue to hatch in a lab at Sonoma State's Rohnert Park campus.

The pond turtles, which grow to about 12 inches long and can live up to 60 years, have suffered because of man's encroachment on their habitat in marshy, boggy areas and the introduction of several nonnative species to their environment.

"For instance, people get Eastern bullfrogs as pets, and then when the frogs get too big to manage, they let them go in the wild," Rousser said. "But those frogs are native to the Midwest and they're voracious predators of the pond turtle, eating the young ones up in one bite. Or they get to the eggs before they even hatch, so the turtles never get a chance.

"Also, the red-eared slider turtles are a problem," she said. "They are also nonnative, and a very common turtle pet. Again, when they get big, people let them loose in a local stream where they compete for resources with the pond turtle.

"And the Sliders have been winning," she said.

Championing the cause of the pond turtle, Nick Geist, a biology professor at Sonoma State -- with help from his graduate students and Oakland Zoo staffers -- spent the summer monitoring a Lake County site for mother turtles, following them to their nests and collecting eggs. Geist then placed 57 viable eggs in five incubators in his lab, and the first six hatched about a week ago. They were delivered to Oakland, and the next group will go to San Francisco. They'll be cared for at the zoos for about a year, until large enough to be released back where the eggs were originally found.

"After raising them under optimal conditions for nine or 10 months, they can get to the size they would grow in the wild in maybe three or four years," Geist said. "At that point, their shell has hardened and they are virtually immune to predators. But as babies, they're tender morsels. The bullfrogs chow down on them like they're popcorn."