Bay Nature magazineSpring 2010


Native Son

April 1, 2010

In 1929, an unremarkable gentleman set out to explore an unnamed creek in an undisclosed corner of California. Wading through the creek that day, scrabbling along its cobbled banks, this “Nature-curious” fellow counted 108 western pond turtles in three miles of running water.

Before Europeans settled the Bay Area, the western pond turtle thrived in large numbers throughout California’s hundreds of rills and rivers. Still, this unremarkable gentleman’s foray, later chronicled in the American Nature Association’s Nature Magazine, remains important for two reasons: His observations were made at the close of more than a century of commercial turtle hunting, and such numbers of turtle were rare then and are even rarer today.

As a Bay Area biologist specializing in the western pond turtle, I have focused over the years on understanding California’s turtle fishery and the effects of this fishery on pond turtles. So I wondered if this unremarkable gentleman’s experience could be re-created 80 years later: If I visited a few creeks and lakes that hadn’t been riprapped, undergrounded, or polluted, would I find western pond turtles in anything like their historical abundance?

In 1841, about 80 years before our unremarkable gentleman’s adventures, Russian naturalist Il’ia Gavrilovich Wosnessenskyi came to Northern California to explore “Russian America,” centered on Fort Ross, near the mouth of the Russian River. Visiting Bodega Bay and the Sacramento River, he collected five western pond turtles, possibly the first pond turtles taken by a scientist in California. They were little different from those found today: up to nine inches long with shells and skin marked with inconspicuous but intricate marbling and stippling in earthy browns, greens, and yellows.

Baby Pond Turtle
Pond turtle hatchlings are about the size of an Oreo cookie. Photo by Matthew Bettelheim.

As years passed, naturalists came to realize that this modest pond turtle (Clemmys marmorata)–ranging from British Columbia south to northern Baja–was the Pacific Coast’s only native freshwater turtle. Compared to more than 20 turtle species on the Atlantic coast, the humble western pond turtle is a remarkably successful and wide-ranging species. And it’s been that way since the dawn of the Pliocene epoch five million years ago when changes in climate and tectonic and volcanic activity displaced its ancestor from the Great Basin into the turtle’s current range.

Despite its success over that vast range, the western pond turtle had grown increasingly scarce by 1992. That year, three herpetologists petitioned the U.S. Fish and Wildlife Service to list it as threatened or endangered. Among the key threats the petition cited were habitat degradation and loss, the spread of exotic predators, and epidemic disease. The petition stated that the western pond turtle was in a “general state of decline through most of its range” and that its future could not be assured. The federal government rejected the petition, explaining that its substantiating information was largely anecdotal.

Red-eared slider faces off with western pond turtle
A red-eared slider, likely an abandoned pet, faces off with a western pond turtle (on right), the West Coast’s only native turtle. Sliders reproduce more quickly and are often more aggressive. Photo by Sarah Anne Bettelheim.

Even now, we lack understanding of threats to the species, population status, and elementary natural history. But with the loss of over 90 percent of California’s historical wetlands–critical turtle habitat–there’s little doubt that western pond turtles face some risk of endangerment.

The pond turtle has been protected to a lesser degree under the California Department of Fish and Game’s purview as a species of special concern. In 2008, Fish and Game contracted a team led by biologists Hartwell Welsh Jr. and Don Ashton of the U.S. Forest Service to develop a pond turtle conservation strategy aimed at preventing further decline. The strategy (due out this summer) will provide resource managers, researchers, and landowners with an encyclopedic review of the western pond turtle: an updated natural history, new survey and monitoring guidelines, an evaluation of threats, and a census of pond turtle populations.

Last year, I set out to go turtling in three locations representative of typical pond turtle habitats: intermittent Kellogg Creek on the northern fringe of the Diablo Range, perennial Alameda Creek in the Sunol-Ohlone Regional Wilderness, and Stow Lake in Golden Gate Park. While my survey wasn’t comprehensive, it did prove to be an apt barometer of what the state’s researchers have been finding.

Late one August morning, from atop Kellogg Creek’s incised banks, I was greeted by deep summer pools crowded with cattails, bulrushes, and scads of California red-legged frogs. Heading upstream, I flushed a coyote, sending him loping into the distance, and then a bobcat that darted for cover.

Turtle specimens, 1862
These illustrations were made from turtles taken in Central California by a Russian naturalist in 1841, likely the first western pond turtles collected by a scientist. 1862 illustration, courtesy Richard Wahlgren.

The creek zagged across a landscape of gentle foothills stubbled in nonnative grasses and weeds, near Los Vaqueros Reservoir. This dry backdrop is surprisingly important to western pond turtles, since females nest in such barren grasslands. Wandering in a seemingly aimless fashion, they scrape false nests to test the ground for rocks or other obstructions. Then, they dig a pear-shaped nest chamber using their hind legs. Inside, they carefully arrange up to 13 porcelain-white eggs before plugging the chamber with hard-packed soil.

The turtles are particularly vulnerable while nesting, exposed to foxes, skunks, raccoons, and other predators. Nests are also prime targets: I’ve seen a meadow littered with eggshells and nest plugs, leaving me to wonder if any of that year’s brood survived. Those that do survive may overwinter in the chamber, or dig their way out in the fall and head for the nearest water. Even then, hatchlings struggle–they are about the size of an Oreo cookie, and about as delectable to many predators.

I continued along the creek, but it was some time before the first western pond turtles betrayed themselves, basking on a log in a man-made pond. Well before I drew near, they scrambled for the water’s safety–kersplunk. A little ways on, I got a glimpse of another lone turtle basking on a root-wad in a languid stretch of creek. But as I stepped out from behind the tree line–kersplunk. Western pond turtles are notoriously skittish: Dropping into the water is their first line of defense against potential predators. In the first of the next three ponds to follow, I could see only the upturned periscope snouts of another five turtles. And in the last two ponds, kersplunk-kersplunk-kersplunk-kersplunk-kersplunk. All told, I counted 16 pond turtles.

Western pond turtles at Sunol
Western pond turtles thrive in some areas, like this pond at Sunol Regional Wilderness in Alameda County. Photo by Karl Gohl.

Alameda Creek was next on my list. Here, at the foot of a steep canyon, alders and grassy tussocks erupted from cracks between the streambed’s exposed bedrock. Earlier that summer, my three-year-old son had pointed out a western pond turtle foraging in the shallows downstream. Moments later, he and I had found several more basking on a nearby snag.

So this time, I gave the shady stretches of creek short shrift. Pond turtles are cold-blooded reptiles that need sunshine to fuel their metabolisms. But in the sun-draped reaches where I’d expect to find turtles basking or foraging, I saw nothing. Continuing upstream, I initiated a relay race with a great egret, repeatedly flushing him until he abandoned his fishing for more undisturbed waters. As noon drew near, the creek’s quiet enchantment was again broken by thumb-size foothill yellow-legged frogs flinging themselves free of my boot-steps.

With not so much as a kersplunk to suggest that turtles inhabited these waters, I was growing disheartened. It seemed early for the turtles to have already retired to their upland winter haunts. River-dwelling pond turtles risk getting flushed downstream during scouring winter rains. One survival strategy is to retreat upland to bury themselves in leaf litter or a protective copse of poison oak. This terrestrial tactic, or hunkering down in the mud-beds of ponds and creeks, also works during summer droughts.

It was time for plan B. Veering off course, I left the creek behind and blazed a trail uphill, climbing for several hours to a little-known pond off the beaten track. I approached the shoreline with caution, wary of flushing my quarry. But there were so many western pond turtles in this tiny pond, flushing a handful would only redistribute them to the sea of snouts eyeing me from the open water. I could actually hear the hollow thump of shells knocking shells as turtles jockeyed for a safe vantage. I was at a loss to figure out what so many turtles were eating in this small pond. Of their omnivorous diet–aquatic insects, tule and cattail roots, carrion–the only thing likely to be available here is algae. And given the number of turtles, even that must have been in short supply.

Turtle net in Sacramento
Fyke nets or “terrapin nets” like this were staked to river bottoms and baited to attract turtles. This fyke, shown in the Sacramento River, had to be checked often to prevent the catch from drowning. 1884 illustration from Fisheries and Fishery Industries of the United States, courtesy Matthew Bettelheim.

This unnatural abundance of turtles in a small, man-made pond is hard to explain. But an early pioneer account once described pond turtles basking in Central Valley wetlands in such abundance that, when flushed, “they popped into the water in a solid mass, making a roar like the surf on a beach.” Indeed, enough pond turtles once inhabited California to drive industrial-scale harvest and rearing of turtles for soups and stews.

Well before European settlers began hunting pond turtles, California Indians practiced their own subsistence harvest. The Clear Lake Pomo “turtled” by startling basking turtles from their tule-clump perches into nets set below the water’s surface. They also dined on turtle eggs, wrapped in grass and baked in ashes.

The popularity of the western pond turtle on California pioneers’ menus likely stemmed from East Coast colonists’ insatiable desire for another turtle, the diamondback terrapin. In San Francisco, diamondbacks were deemed “the inevitable stuffing of the ‘upper crust.'” Entrepreneurs like Fish Commissioner Henry F. Emeric (a charter member of the Sierra Club) imported diamondback terrapins to the marshes around San Pablo and Redwood City in attempts to establish populations in San Francisco Bay. But by 1863, California markets had accepted western pond turtles as a substitute. Enterprising market hunters harvested western pond turtles with traps and quarter-mile-long nets. They shipped their catch in barley sacks to supply exclusive clubs, hotels and restaurants, Chinese clientele, and venues like San Francisco’s “entrepot of foods,” the California Market, a “great bazaar of flesh and fowl and game.” By the 1880s, several thousand turtles were taken annually in Central California. In 1899, a record 53,935 western pond turtles were reported in the markets.

From that height, the industry petered out. Prohibition may have been a key driving force, given that terrapin dishes were often baptized with sherry, white wine, Madeira, or brandy. Neatly coinciding with the western pond turtle’s growing scarcity, the market demand for them winked out.

As luck would have it, so too had any populations of introduced diamondback terrapins. Still, individual diamondbacks lingered on. In 1966, a review of reptiles in San Francisco County reported mostly nonnative turtles in Golden Gate Park and the occasional diamondback terrapin–a possible relic of the past commercial market.

Family watching turtles at Stow Lake
A family watches turtles sunning themselves at Stow Lake, one of few places many people are able to encounter wild turtles of any kind. In Golden Gate Park’s highly altered landscape, native turtles vie for space with a bevy of exotic species. Photo by Sarah Anne Bettelheim.

So I began my circuit of the park’s Stow Lake–my last stop–with low expectations. By midmorning, soon after the sun edged out the fog, turtles began clambering onto rocks and logs to bask. Sure enough, western pond turtles didn’t rank among their numbers. Instead, bold red badges and yellow stripes advertised a host of nonnative species–red-eared sliders and western painted turtles–all former pets whose cuteness had expired.

In 1997 alone, Louisiana turtle farms exported more than 8.7 million sliders for the international food and pet markets. These same farms also supply the domestic pet trade, though numbers are hard to come by. While we don’t know the specific effects exotics have on western pond turtles, we do know that sliders grow larger, are more aggressive when basking, lay larger clutches more often, and bring with them exotic pathogens and diseases. Since both species’ niches overlap, sliders are well positioned to outnumber and out-compete western pond turtles.

In the afternoon at Stow, I finally saw my first western pond turtle, sunning on a log occupied earlier that morning by a slider. As he held his ground against an armada of discarded pets angling to bask atop him, I noticed a second pond turtle watching me from the murky waters at my feet. Moving toward the boathouse, I spotted the marbled throats of two more western pond turtles amid another lineup of dime-store discards. If the pond turtles felt threatened by their apparent minority status, they didn’t show it. By day’s end, I’d counted more than 90 turtles, five of them western pond turtles.

Whenever I stopped to observe turtles basking, I attracted a gaggle of human onlookers. “Ooh, look, turtles!” they’d say. A few took pictures before wandering off. Just “turtles.” It’s this lack of awareness that Ashton, Bolster, and biologists like me are working to address–to re-introduce “western pond” back into Californians’ idea of “turtle,” and secure the future of our sole native turtle.

That will take the work of both scientists and citizens. Ashton says there simply aren’t enough researchers studying the species, nor are enough of them publishing their results. The forthcoming conservation strategy will encourage future pond turtle studies across the state, prompting researchers to share and publish existing data sets. Improving existing habitat could also help: Ranchers and land managers can anchor auxiliary basking logs in stock ponds and lakes to give native pond turtles a leg up. Likewise, removing nonnative predators like bullfrogs and bass can help young turtles survive to adulthood. For the wider public, the most important act is simply finding good homes for unwanted pet turtles instead of releasing them in the wild.

As for me? I may not have found western pond turtles in the wild abundance I had hoped for, but those I did find had clearly persevered in the waters left to them. And yet, if ever there were a time the pond turtle needed help from us, it’s now. I’ve run my fingers over aged turtles’ shells marbled with weathered scars, testaments to surviving predators’ piercing teeth and other traumas. But if there’s one thing my work with western pond turtles has taught me, it’s that a turtle’s dogged determination to survive can carry it only so far. A shell protects one turtle at a time. The rest is in our hands.

About the Author

Matthew Bettelheim is a freelance writer and a wildlife biologist with URS Corporation.