Oakland Zoo in partnership with the San Francisco Zoo and Sonoma State University has begun the first Western Pond Turtle head starting program in California. As the only native freshwater aquatic turtle that resides in California, Dr. Nick Geist, professor at Sonoma State Univeristy recognized a dearth of information on the species and set out to correct it. He immediately enlisted the help of Oakland Zoo and San Francisco Zoo who were eager to assist. Dr. Geist oversees research along with his graduate students that has allowed us to expand our knowledge of the Western Pond Turtles' diets, home range nesting grounds, nest fidelity, egg incubation conditions and temperature dependent sex determination.
Each nesting season, Oakland Zoo, San Francisco Zoo and Sonoma State students spend a month tracking, marking and monitoring gravid female turtles. Nests are then either protected with exclusion devices to prevent predators from digging them up or the eggs are collected and incubated in the lab at SSU. Hatchlings are raised in optimal conditions for 1 year at the zoos before being released back into the wild, strong enough to thrive. As of 2011, more than 100 turtles have successfully been released back into the wild.
Western Pond Turtles were once plentiful and ranged from as far south as Baja California to as far north as British Columbia. For many years their habitat range has been shrinking and they are currently only found in parts of California and Oregon along with two small populations in the state of Washington. Their shrinking populations are credited to habitat loss, non-native predators and crowding by non-native turtle species. Our current efforts at reintroduction are focused on a few pristine lakes where non-native turtles have not yet made an incursion.
American bullfrogs are native to the East coast states in the US. Early settlers had a taste for frogs and nearly wiped out the California red legged frog for their dinner plates. To keep up with demands in 1890's American bullfrogs were imported from the east coast. The large and aggressive frogs eat other frogs, and hatchling turtles. Largemouth bass are often stocked in local lakes during fishing season for the benefit of sport fishing. Unfortunately as their name implies, a hatchling turtle is easily bite sized for them.
Many species of turtles are very commonly sold in the pet trade. Turtles however are long lived and require very specific conditions to thrive. Many well-meaning, but misinformed pet owners have released their pet turtles into the "wild" thinking that they were doing their pet a favor. Unfortunately, the most common of these is the red-eared slider who is very gregarious and naturally "pushy." These turtles easily out compete our own shy Western Pond Turtle who misses out on food resources and is pushed out of basking spots.
Research: Learn about the biology and behavior of the Western Pond Turtle as we can, before it is too late.
Release young, healthy turtles back to the wild: Identify additional sites for turtle release. Monitor these sites long term to determine their viability in the future.
Outreach and education: Get the word out about our only native aquatic turtle and inspire a sense of pride in the community towards the Western Pond Turtle. Educate the public about the hazards of introducing non-native species into their local environment.
Research: Through the research being done at Sonoma State University and Oakland Zoo and San Francisco Zoo, we have amassed a large body of knowledge about the behavior and biology of Western Pond Turtles. We know that their nesting sites are often very far from their ponds and we can accurately predict the sex of the turtles based on the temperature of the nest site. This means that conserving their habitat is even more important than we previously knew.
On site help for turtles: Oakland Zoo is also "head starting" the turtles which means that by raising the hatchlings in optimal conditions for their first year they are too large to be easily swallowed by the American bullfrog or largemouth bass. By reaching the size of a three to four year old turtle in a single year, they are less likely to be targeted by other predators and are more prepared to survive the winter.
Outreach and education: Zookeepers and educators at both zoos attend local festivals and meet with local conservation groups to get the word about the plight of our Western Pond Turtle.
Expertise in the field: Zookeepers and Researchers work together during the field season using telemetry to track gravid females, using GPS to mark nesting sites, placing predator exclusion devices over recently laid nests and tracking the presence of predators in the area.
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Western Pond Turtle