Frogs peer up at me, or so it seems, with bulging eyes while basking picturesquely on lily pads, or resting in the mud. And they plop cutely into the water as I walk carefully along the edge of a small livestock pond on East Bay Regional Park District land in remote southeastern Contra Costa County. From below the pond surface, California tiger salamanders stealthily come up to gape for air, creating gentle concentric circles in the water.
“If it’s the tiger salamander, they only just barely break the surface,” explains Mark Gary, a park district volunteer from Livermore, who is showing me how to identify amphibians in a pond he’s been observing for over a decade. “The young metamorph frogs are clumsy. They make a bigger splash.”
I’m on a field trip with amphibian-loving scientists and ecologists—members of the park district’s devoted pond team—to see for myself how water-loving species are doing in livestock ponds, which were built in the mid-20th century by East Bay ranchers to provide their cattle with fresh water. Today as many as 600 artificial watering holes dot district and watershed lands across Alameda and Contra Costa counties, and in an ecological twist of fate, many of them are the centerpieces of essential habitat for at-risk amphibians and reptiles. But the ponds are deteriorating—a process occurring naturally with age, but exacerbated by climate-related extreme weather events. The park district and its partners face a growing backlog in need of restoration, not only to provide water for grazing cattle but also to preserve shrinking amphibian habitat.
“In an ideal world we would provide completely natural habitat for our wildlife,” says Natalie Reeder, park district wildlife biologist. “But the reality is that a lot of the natural wetland and pond habitats have been destroyed either by development or diversion or some other kind of manipulation of the land, so these cattle ponds are really the last refuge for a lot of these species. They are what we have, and what these animals have to survive.”
Listed as threatened in the state, California red-legged frogs (Rana draytonii) and California tiger salamanders (Ambystoma californiense) are doing just fine here, and the pond team is over-the-moon excited. There are more frogs than I can count just in the pond in front of me.
“It looks like a muddy, turbid little watering hole,” says Allison Rofe, a park district rangeland specialist, standing with me at the pond’s edge. “But in reality it’s overflowing with life. There’s so much activity it almost looks like the pond is bubbling.”
Amphibians, cattle, and grassland
Mammoths, ground sloths, horses, and camels roamed the East Bay hills until their extinction around 11,000 years ago, as did the grazers, such as deer, elk, and antelope that live on in California. These large mammals coevolved with amphibians and native perennial grasses and forbs, and Indigenous people lived alongside them, often deploying fire to manage grasslands. After Europeans arrived, California grasslands and oak woodlands became dominated by cattle and invasive, nonnative annual grasses like wild oats and soft chess, and the wetlands that amphibians need to breed and thrive were steadily filled in for urbanization and agriculture.
Many large, private ranches in the hillier areas of the East Bay have become part of the park district over its 90 years, but livestock grazing continues. Today the park district leases about 70 percent (nearly 87,000 of its 126,000 acres) for grazing by 5,000 or so head of cattle, as well as goats and sheep.
When cattle come to the ponds to drink—each one needs on average 10 gallons per day—they unintentionally help the amphibians. Around the ponds, cattle eat and trample down dense thickets of tall grasses that would otherwise shade water at the surface, preventing it from reaching temperatures at which red-legged frog larvae develop. Also, tiger salamanders prefer short or no vegetation around ponds, so they can more easily travel to the upland ground squirrel burrows where they spend most of their time when they’re not breeding.
In past years, state and federal fish and wildlife agencies recommended fencing off ponds on rangelands to keep out grazing cattle, says Matthew Graul, park district chief of stewardship. “We did pioneering research which showed that when you do that, it chokes out the ability of the amphibians to get into the uplands, and populations would at times crash.” Likewise, amphibians prefer cloudy, turbid water kicked up by cattle because it provides cover from predators like great blue herons and egrets.
Researchers noted in a 2014 article in the journal Rangelands that “a major factor contributing to the conservation of [California tiger salamander and California red-legged frog] in rangelands is the use of stock ponds for their breeding. Additionally, by reducing the aboveground biomass accumulated by annual grasses, cattle grazing can facilitate [their] movement and dispersal.” (While cattle are welcome in and around livestock ponds, people and dogs should steer clear to protect amphibians and other aquatic life.)
Rancher Ron Batteate has been grazing around 250 head of cattle in this parkland (which shall remain unnamed, to protect endangered species) for the past 30 years. “The frogs and the salamanders have been there for tens of thousands of years. They need that interaction with the livestock—if not cattle, then elk, deer, whatever—and they all get along just fine.”
Park district ecologist Tammy Lim wholeheartedly agrees. “It seems weird that cows are helping us save or manage habitat for California red-legged frogs and California tiger salamanders, but they are.”
Pond #9 gets a makeover
It’s one of those sparkling clear and cool Bay Area fall days, as we ramble along the trail to explore ponds. Framed by a backdrop of golden oak woodlands, dragonflies dance above the surface of pond #9. Black phoebes flit back and forth from snags, turkey vultures make lazy circles overhead, and California ground squirrels patrol the uplands. The pond team points out a western fence lizard (Sceloporus occidentalis) at the edge of a ground squirrel burrow, a garter snake harassing a young red-legged frog, and an adorable teeny Pacific chorus frog (Pseudacris sierra).
Smaller than a lake, bigger than a puddle, deeper than a vernal pool, and not exactly a marsh, ponds are depressions in the landscape that hold water from surface flows, seeps, or springs. On park district lands, ponds average one-fifth of an acre (about 8,500 square feet) and are usually shallow, just three or four feet deep, like pond #9. A pond will be an attractive place for amphibians to breed if it holds water for six to nine months of the year, the time frame called its hydroperiod.
Ranchers likely dug out these ponds in places where water was already collecting to make them larger and deeper, along with building berms or small dams. “Before permits, ranchers would go around and excavate areas that were already somewhat ponded, or wetlands, and make them deeper so they would hold water for longer,” Lim says.
The lifespan of a constructed livestock pond is about 20 years, and ponds need regular upkeep. When they fill with sediment, they dry up more quickly, reducing the hydroperiod and the window of time during which amphibians have to breed, and wear and tear on pond infrastructure can cause ponds to fail. When a berm or dam breaks, the pond erodes and can just wash out down the hill, and any animals in their aquatic stage, whether they were eggs or larvae or tadpoles, will not survive.
Which is exactly what happened with pond #9. The berm had been eroding since before Batteate began grazing his cattle here in the 1990s. Water seeped into ground squirrel burrows, which facilitated years of erosion, and the embankment ultimately collapsed during the rainy season of 2014–15, landing pond #9 on the park district’s restoration list.
Options for restoring ponds as amphibian habitat include removing excess sedimentation to extend the hydroperiod; rebuilding berms, dams, and culverts; and draining them to try and eliminate nonnative fish and bullfrogs that like to dine on smaller amphibians at all of their development stages.
At a cost of $50,000 to $150,000 each, pond restoration is limited by available funds from a variety of sources including the park district, Natural Resources Conservation Service, local conservation districts, state drought-related funds, ranchers, and other grants. Given the 20-year lifespan of a typical pond, the pond team estimates that it would need to restore 25 ponds every year to keep up with the backlog.
“Over the past 10 years the pond team has restored about 60 ponds in 20 parks, and we have identified 16 failed ponds to prioritize for restoration over the next five years,” says Edward Culver, a park district fisheries biologist.
Pond #9 received its makeover in 2017, during the two-month window in late summer when ponds are driest, minimizing the risk to sensitive species, and when the park district is permitted to make repairs without being penalized by regulators for accidentally harming endangered species.
It took years, but the park district has created a framework with the myriad regulatory agencies that allows the district and its partners to undertake pond restoration and enhancement in areas where California red-legged frogs and California tiger salamanders may be present, because the work would improve endangered species habitat and provide climate resiliency.
“We’ve removed permitting as the primary obstacle,” says Becky Tuden, the park district’s environmental services manager. “Our staff and the park district did a great job weaving that path so that we could improve the pace and scale of our pond restoration programs.” To build pond #9’s berm back up, the park district borrowed topsoil from a nearby location without taking any sediment out of the pond and added a rock-armored spillway, which now channels overflow from pond #9 to pond #10 below. When we wandered by pond #10 earlier, six western pond turtles (Actinemys marmorata), a California native freshwater turtle and a candidate for the federal endangered species list, lazed on a redwood plank that Culver had placed just for them.
I crouch at the edge of pond #9 next to Gary, the pond team’s beloved community scientist, admiring the young California red-legged frogs. Gary saw pond #9 through its restoration, and he’s delighted to see it hopping with metamorphs in early fall. “I’ve never seen so many in one place before,” he gushes.
Gary and I continue walking up the trail from pond #9, across a meadow, and through a cattle gate and to pond #25, where, the pond team excitedly tells me, a remarkable resurrection occurred.
Pond #25 restores itself
Not long ago, restoring amphibian habitat at pond #25 seemed like a lost cause. Larger than pond #9 and quite deep at 20 feet, pond #25 is a perennial pond that earlier ranchers had stocked with fish. While fishing has never been allowed in this park, pond #25 definitely saw its share of anglers over the years. “My grandkids fished in there from when they were little-bitty guys,” says Batteate, recalling a four-pound bass that his grandson caught and released.
A June 2020 park district survey found no amphibians in pond #25. “Because of the fish, there was nothing else in the pond,” Culver says.
Competitors not native to California that take up residence in ponds—often unwanted pet bullfrogs, fish, or turtles released by people into the parks—wreak havoc on amphibian populations. Nonnative fish stocked in perennial ponds like #25 also eat amphibian eggs and larva. About 60 ponds in the park district have fish or bullfrogs in them. American bullfrogs (Lithobates catesbeianus), which also may be escapees from the food trade, are at least twice the size of California red-legged frogs; voracious eaters, they can quickly clear a pond of virtually all other amphibians. Likewise, red-eared sliders (Trachemys scripta elegans), a common pet turtle, outcompete western pond turtles for food, egg-laying sites, and places to bask.
Climate change is hitting livestock ponds on two fronts. Extreme rain events, like the onslaught of atmospheric rivers that drenched the West Coast during the 2023–24 rainy season, caused about 30 East Bay ponds to fail. Extreme heat and droughts like the one in 2020–21 cause ponds to dry up faster, shortening hydroperiods and reducing amphibian breeding success.
That drought dried up the very deep pond #25, killing all the nonnative stock fish; then the pond quickly filled up during the subsequent wet winters. The pond team was overjoyed to see #25 bursting with young amphibians, which likely arrived here from ponds #9 and #10 to breed. On the day of our field trip, the team estimated that #25 contained around 1,000 California red-legged frog metamorphs and seven adults. “I don’t think we’ve ever seen that many right after a pond went fishless,” says Lim, the park district ecologist.
“This pond is in the ‘If you build it they will come’ model of restoration,” says a beaming Ben Weise of Contra Costa Resource Conservation District, which partners with East Bay ranchers and the park district to restore ponds. “It makes me so happy.”
Regardless of the obvious benefits for amphibians in pond #25, time and extreme weather events wrought by climate change will continue to stress the East Bay’s livestock ponds, the amphibians that rely on them, and the pond team, which struggles mightily to keep up with the backlog of failing ponds.
“You might go to our parks and think, ‘Wow, the frogs and salamanders are thriving here. Is this really an endangered species?’” Graul says. “But the range of these species has been significantly reduced, and there aren’t many in other areas where they used to be. That’s why our ponds are so critical to the success and persistence of these species. We have some of the last remaining intact populations.”
This article has been read and paid for by the East Bay Regional Park District.
