They may be slow, but they’re not easy to find: Keeping up with the elusive Western pond turtle

They’re famously slow. They’re also omnivorous, eating everything from insects and aquatic plants to carrion. And they are willing to stick their necks out each and every day, despite a host of dangers that lurk in dark crevices and reeds.

Western pond turtles, California’s only native freshwater turtle species, are trawling the ponds in the Santa Cruz Mountains, sunning on logs and keeping the mosquito population in check. But this most important species and indicator of ecosystem health is also highly vulnerable — listed by the state of California as a “species of special concern.”

The population has been reduced over time because of loss of habitat, predation and competition from non-native species, such as red-eared sliders, said Midpeninsula Regional Open Space District biologist Karine Tokatlian.

Now, a new program launched by the district aims to help these creatures thrive. Last month Tokatlian launched a new turtle-tracking project through the Midpen Biodiversity Index at the online app iNaturalist. The district is asking people to be on the lookout for the turtles. Through the app, people can upload pictures of the turtles they spot and include data such as time of day, where they were found, turtle activity and other measurements that will help scientists understand the turtle populations and the quality of their environments.

Participants can take a short introductory training with Tokatlian or simply report their findings.

Scanning for the turtles with binoculars on Wednesday morning, Tokatlian searched the sunning platform and edges of reeds and grasses of Alpine Pond above Palo Alto where the creatures might be found. Every stick protruding from the water seemed to hold some promise of a head poking up, but the five or so turtles known to live in this pond were no-shows that day.

Western pond turtle “bachelors” are at the district’s newest preserve, Bear Creek Redwoods Open Space Preserve near Los Gatos. Tokatlian estimates that about 300 turtles reside at La Honda Creek preserve and they are present at Windy Hill, Russian Ridge and Sierra Azul open spaces.

They are usually found in aquatic areas such as ponds, lakes, creeks and rivers, but they also leave the water to search for food, other water sources or to lay their eggs in the spring in sunny, grassy areas near streams or ponds.

These dry-area locations are of particular interest to Tokatlian because they indicate possible nests, a sign that the habitat is healthy for the turtles, she said.

“If you see a turtle in these areas, do not disturb them. Contact us so that we can monitor potential nesting sights,” she said.

Western pond turtles don’t breed until they are 8 to 10 years old. Although they have hard shells, as juveniles and hatchlings, the shells are soft, making them easy prey. Pond turtles are about 4 to 8 inches in size and can live for about 14 years. They have smooth, flattish-domed shells that are brown or blackish and are smooth around the edges of the shell. Other turtle species tend to have higher domes, she said.

Red-eared sliders, an invasive species, are distinguishable from pond turtles because they have red markings near their eyes. They also have notches along the edges of their shells. These are the turtles most people have as pets, along with painted turtles. Once they become unwanted pets, people sometimes deposit them in creeks and ponds where they out-compete the pond turtles for food, critical basking locations that regulate body temperature and other habitat.

Red-eared sliders also have larger clutches of eggs — twice as many as pond turtles, which lay two to 11 small, white oval-shaped eggs. Red-eared eggs hatch earlier than pond turtles, so they can take advantage of establishing dominance over resources, she said.

These invasive species can be prolific. During an attempt to trap an invasive snapping turtle at Windy Hill, biologists caught 10 red-eared sliders and painted turtles, another invasive species, and only two Western pond turtles over a two-week period, Tokatlian said.

The pond turtles are an important species that contributes to the overall health of the ecosystem, she said. They take less energy out of the food they consume than do other species and leave behind what remains for other creatures to feed from the pellets they excrete. They eat decaying vegetation and insects.

“We are using them as an indicator of what’s happening around us — to see if they are healthy and abundant — and we are using their behavior to gauge the health of the pond habitat,” she said. With the information they gather, scientists will be able to better manage the pond resources, which will benefit all of the creatures who rely on the water.

To learn about the turtle-tracking project or to sign up for a training session, people can visit openspace.org.

What to do with unwanted pets

Pet lizards, reptiles, frogs and turtles should never be released into the wild. If a pet is no longer wanted, it can be given to the following rescue groups:

* Peninsula Humane Society & SPCA: phs-spca.org/

* Bay Area Turtle and Tortoise Rescue: 510-886-2946

* Bay Area Amphibian & Reptile Society: baars.org

* Joe and Wendy’s Reptile Rescue: 707-557-5213

CORRECTION: A previous version of this story stated there are 300 turtles at Bear Creek Open Space.