California’s only native freshwater turtle species got a “headstart” from a team of federal, state and zoo scientists, who released five juvenile turtles into the Sycuan Peak Ecological Reserve today.
These new arrivals are western pond turtles Emys marmorata, a species once widespread in California, Oregon and Washington but now especially uncommon in southern California due to habitat loss and invasive, nonnative predators like bullfrogs and largemouth bass, which eat up the tiny hatchling turtles that measure no larger than a quarter.
The Sycuan Peak effort is a joint project of the U.S. Geological Survey (USGS), the San Diego Zoo, the California Department of Fish and Wildlife (CDFW) and the San Diego Association of Governments (SANDAG) testing conservation strategies to help western pond turtles and other native species, since many California ecosystems are being impacted by invasive, nonnative species accidentally or intentionally introduced by humans.
“Three years ago, we collected gravid female pond turtles from the Sweetwater River at the Sycuan Peak Ecological Reserve and brought them to the San Diego Zoo to lay their eggs,” said Chris Brown, a reptile ecologist with the USGS Western Ecological Research Center. “We wanted to raise their offspring in captivity until they were large enough to avoid being eaten by predators. In the meantime, we removed nonnative predators from the river within the Ecological Reserve so we could introduce these baby turtles back into a safer, more natural habitat.”
Zoo scientists call this their “headstarting” program for turtles, raising the hatchlings to a size large enough to give them a better chance of surviving in the wild and fending off natural predators.
Researchers had not detected juvenile pond turtles at the Sweetwater River in nearly a decade and suspected nonnative predators were to blame. Only after the restoration efforts and invasive species removal efforts began did they begin to find new juveniles, and researchers have continued to detect them for three years now. The headstarting project will further bolster the local recovery of the western pond turtle.
“We have been studying western pond turtles in Southern California for many years and know that they are struggling, particularly in San Diego County,” said Thomas Owens, senior keeper with the San Diego Zoo’s Department of Herpetology. “We are very happy to partner with the U.S. Geological Survey, the California Department of Fish and Wildlife and SANDAG in this very worthwhile project.”
Now measuring about the size of an iPhone, the turtles are also big enough to wear miniature radio transmitters. Researchers attached these tiny antennae to the baby turtle’s shells so they can regularly check on the turtles’ growth, physical health and behavior.
“Efforts like this are one of the main reasons we maintain a strong state ecological reserve system and acquisition program,” said Terri Stewart, an environmental program manager with the CDFW South Coast Region office. “We are excited for the opportunity to help western pond turtles regain a foothold in their historic habitat, while demonstrating the ecological value of the Sycuan Peak Ecological Reserve and exposing the impacts of nonnative species on native wildlife.”
More baby turtles are currently being reared by the San Diego Zoo, and they will be released into the wild once they reach sufficient size. The mother turtles for all these offspring were returned to the Sweetwater River study site soon after they laid their “eggs of hope” at the Zoo three years ago.
The San Diego Zoo Global Wildlife Conservancy is dedicated to bringing endangered species back from the brink of extinction. The Conservancy makes possible the wildlife conservation efforts (representing both plants and animals) of the San Diego Zoo, San Diego Zoo Safari Park, San Diego Zoo Institute for Conservation Research, and international field programs in more than 35 countries. The important conservation and science work of these entities is supported in part by The Foundation of the Zoological Society of San Diego.
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