San Diego Pond Turtle Population on the Rebound
Most San Diegans will live and die here without ever having seen one.
Shy to an extreme, they are the color of pond mud and shaped not unlike the river stones in the riparian streams they inhabit. As such the Southwestern pond turtle, the only turtle indigenous to our area is an enigma. “Even people who live near pond turtle habitats have never seen one,” says Thomas Owens. “They’re surprised to learn that we have native turtles.” But the pond turtle’s inherent cloak of invisibility is not the problem. The larger issue is that it is perilously close to going extinct in this region. In recent years, a field survey performed by the USGS was able to account for only 120 individuals or so, broken up into small and isolated populations throughout local waterways. But at one time Owens, a senior reptile keeper at the San Diego Zoo believes they were abundant in virtually every stream, lake, and pond in the county. The Western pond turtle, of which the Southwestern pond turtle is a subspecies has an enormous range, from the Baja peninsula north through the states to Washington. It is endangered throughout much of that range and from a variety of maladies: development, habitat destruction, pollution, and the introduction of non native species. In San Diego, says Owens, voracious non natives such as the bullfrog, and turtles that have been turned loose by their owners are out-competing our indigenous pond turtles for food and other resources. “People will release their pet turtle, thinking they are doing the best thing for it.” They are not, Owens says. Pet shop staples such as red ear sliders actually flourish in our waterways and are commonly seen basking on the banks of golf course ponds or swimming in the lower San Diego River in Mission Valley. “They’ve been here so long now,” he says of the red ear sliders, “that people think they’re natural.” Add to the list two other species not native to San Diego waters: large-mouth bass and green sunfish, both introduced for sport fishing. Owens and a team of researchers have been studying our shrinking pond turtle populations in the wild since 2003. In 2009, the USGS, the San Diego Zoo, the California Department of Fish and Game and the San Diego Association of Governments (SANDAG) began a program to save them. Part of the program includes captive-breeding at the Zoo, then releasing head-started juvenile turtles into protected study ponds in San Diego’s back country. So far, so good, says Owens. In August he told the annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles in Orlando, Fla. that wild hatchling turtles had been spotted at the Zoo’s study sites. “If there’s any chance of them rebounding,” he says, “this is it.” Curious as to what our native turtles look like? The San Diego Zoo maintains a dozen or so Southwestern pond turtles on display in outdoor pools near the Reptile House and on the Elephant Mesa. Admittedly, our pond turtle is only a small piece of the whole of San Diego’s ecology, but in a grander scheme of global species significance, that’s enough for Owens. “If we lose these turtles,” he says, “then we’ve lost a chance in our own backyard to make a difference.”