The small island in an Oakland marsh is almost entirely covered in cudweed, and that’s not how the California least tern likes it. Though the patches of vegetation are less than a foot high, this native tern is even smaller, the smallest of the North American terns, about the size of a robin. The tiny shorebird has been on the endangered species list since 1970, and for this patch of shale to be attractive for nesting, they need clear sight lines to evade gulls, crows, and other predators.
That’s why more than two dozen volunteers met one Saturday morning in late January at the Martin Luther King Jr. Regional Shoreline, tucked between the Oakland Coliseum and the Oakland Airport, for a day of weeding. Here, as you walk along the shoreline’s paved pathways, you’re apt to see both geese and airplanes take flight.
David Riensche, the wildlife biologist leading this expedition, has been doing his part to save the California least tern for three decades. As a biologist with the East Bay Regional Park District, he’s been publishing research on how much ground cover they like — sparse — and what kind of surface they prefer — crushed oyster shells mixed with sand — then setting up partnerships with Point Reyes oyster farms for donated shells and organizing volunteers like these, by the thousands, to move earth and shells, to document seagull activity, and to weed.
I asked Riensche how the California least tern first caught his eye.
“Maybe it’s the way it hovers delicately in the breeze,” he said. “Maybe because it’s one of the smallest of the terns, the underdog of terns. Least terns are amazing. They look like little angels hovering above the wind and waves.”
More than 25 years ago, he hatched an idea: What if the East Bay’s waterfront parks could contribute to the California least tern’s federal recovery plan — the official roadmap for saving the species? The plan suggests that the breeding population in California needs to grow to at least 1,200 pairs, distributed among a variety of coastal management areas, including in the San Francisco Bay.
At the time the recovery plan was written, more than four decades ago, less than a dozen fledglings were counted each year in all of Alameda County. The species was on the brink.
Riensche, who looks like Sam Elliott in “Tombstone” if Elliott had a tern stuffie tucked into the brim of his hat, is known to his volunteers as Doc Quack, and he has loved birds for as long as he can remember, since he was a kid and wished he could fly himself; since he spent hours whiling away time on the beach, watching sea birds as his dad, a Marine, did his drills. He begins each volunteer work shift with a song that involves his volunteers flapping their arms like wings and making the “pweep, pweep” call of a plover.
The small island the volunteers are weeding today is deep in the shoreline’s marshes, a stopover on the Pacific Flyway, one of North America’s major north-south migration routes, which runs from Alaska to Patagonia. To get there, volunteers pull on life jackets and get hauled over in a rowboat, four or five at a time.
One volunteer I spoke with, Young Whan Choi, an Oakland educator, came with his 13-year-old son, an avid birder. “He got our family into birding,” Choi said, “and now we all love it.” The pair showed up at 9 o’clock on a Saturday morning because they wanted to do their part to protect the habitat of threatened shore birds, Choi said, and because Doc Quack, whom they met at a plover count last fall, “brings so much joy to this.”
Jaimie Goralnick, an Oakland physician, also came because of her son, a 14-year-old who hosts his own zoology podcast and wants to be an ornithologist. Her son, a pair of binoculars around his neck, said he’s been fascinated by birds since the fourth grade.
Though it was the first time out with Doc Quack for Jaimie and her son, another volunteer, Maggie Clark of Lafayette, said she’d been joining Riensche in his preservation efforts for 25 years. She’s painted decoys and shelters to attract terns, participated in bat counts and plover counts, and she’s spent endless hours documenting the presence of seagulls and other predators near tern and plover nesting habitats.
“I love being outdoors,” she said. “My friend and I bring our chairs and our tea and we talk.”
Preparing bird habitats to withstand rising seas
Many of the marshes along the eastern edges of the San Francisco Bay were diked for use as commercial salt ponds by the 1850s. Restoration of one stretch, the Hayward Marsh, just about 10 miles down the shore from the MLK Shoreline, began in the early 1980s, around the time that Riensche started his research as a graduate student.
“They’d fill with water in the winter and get brinier and brinier until they became salt flats,” Riensche told The Oaklandside. Getting tidal water flowing again, and turning those salt flats back into mud flats and then into tidal marsh, took 30 or 40 years, he said. He remembers when pickleweed, a cornerstone species in marsh restoration, first started sprouting in the mud flats, early in his career. “Now,” he said, “the wildlife are fully using the site.”
In December, the East Bay Regional Park District, which has been managing the Hayward Marsh, acquired 77 new acres of shoreline property to expand these restoration efforts.
The small island of oyster shells at MLK Shoreline is still in the experimental stages; Riensche said a few terns tried nesting there last season, but crows and ravens raided their nests. It turns out there’s another island, in the Hayward Marsh, that is much farther along.
Riensche took me and photographer Jungho Kim out one day in January to show us the spot once called Island Five, which Riensche and his battalion of volunteers began building in 2001. He said it took 8,200 wildlife volunteers and 50,000 hours of volunteer time over three or four years to build the island by hand, heading into the marsh on small boats with three-gallon buckets of sand mixed with crushed oyster shells. They then installed what he called “social attractions” — recordings of tern calls and painted decoys — to lure the endangered birds there, and put up scarecrows to chase off predators. Eventually, in 2003, six pairs of California least terns came. And then, in 2006, successful hatchlings.
Now the colony is growing far faster than the only other significant Bay Area breeding ground, at the old Naval Air Station in Alameda. In some recent years the nest count has topped a hundred. The island has a new name: Tern Town USA. And Riensche has started to imagine that the California least tern, like the bald eagle, could someday be delisted as an endangered species.
Tern Town now attracts Western snowy plovers, a threatened species that also loves oyster shells, as well as Black Skimmers and Black oyster catchers, both California species of special concern. They find a sense of safety together, Riensche said, as they all collaborate to protect one another from predators. Another attraction, he said: “The abundance of the fishery; with topsmelt and grunion, they don’t have to fly far to feed. It’s also a heavily managed site; we’re doing a lot to keep the vegetation down, and the site is watched for predators seven days a week.”
The levee we’re walking on is closed to the public, because it’s so close to the nesting area, but Riensche says the East Bay Regional Park District is planning raised trails and observation spots that will be close enough to see the birds but far away enough not to disturb them. “You can actually see the island now from the San Francisco Bay Trail,” he said, “and there’s an interpretive panel about the Cogswell Marsh about 300 meters from the island.”
His latest adventure is to protect all of the precarious birds he studies — the California least tern, the Western snowy plover, the Black skimmer, and the Black oyster catcher — from the threat of climate change.
Rising sea levels, extreme heat, and changing offshore currents could all threaten Tern Town, the colony he has devoted his life to cultivating and sustaining. So as soon as March, a plan will reach the park district board of directors to build two islands further inland that can withstand significant sea level rise. The permits are all in place, he said, and he hopes he’ll be approved to start construction this fall.
Meanwhile, levee improvements are underway in Hayward Marsh and along the San Francisco Bay Trail to protect against shoreline erosion and flooding and to allow the marsh to migrate as sea levels rise.
“It’s a long game,” Riensche says of his efforts to save one small species of tern. “It outlives the life of a wildlife professional.”
Register to join one of Doc Quack’s volunteer crews at the East Bay Regional Park District.
