Migratory Birds Return As Salt Ponds Heal: Documenting a Damaged World in Transition

Once the groundwork has been laid according to a specific pond’s fate — levees raised or lowered, earth graded to the desired slope, flood channels added or gated — volunteers from Save the Bay work with project biologists for what Donna Ball, a San Francisco Estuary Institute The biologist and lead scientist on the SBSPRP, says is one of the most important parts of restoring the ecosystem: replanting vegetation. “Putting plants in is really the habitat piece,” Ball says. “It’s really the meat of trying to think about each species and what they might need.”

To date, around 3,000 acres have been restored to tidal wetlands and 700 acres of ponds have been enhanced. Just as the first plants 3,000 years ago provided the foundation for the wetlands — and all the biodiversity they support — these initial plantings are bringing life back to the landscape.

In 2014, just eight years after breaching the first ponds, Ridgway’s rails were discovered meaningdering through the marsh. A year later, researchers found salt marsh harvest mice (Reithrodontomys raviventris), an endangered species endemic to the Bay Area, scampering around dense carpets of pickleweed. Even threatened longfin smelt (Spirinchus thaleichthys) and other local fishes were visiting the surrounding waters in greater numbers than before.

The wetlands were returning much faster than anyone had anticipated. “We had thought that it would take longer,” Ball says. “It’s great to know that we’re having a positive effect.”

Importantly, even with the number of artificial salt ponds shrinking, improvements to those that remain has actually increased migratory water bird numbers. A study from the US Geological Survey found that between 2002 and 2014, the number of overwintering water birds (both waterfowl and shorebirds) that stopped over in the project area more than doubled. By comparison, in nearby ponds still owned by Cargill for salt production, there was virtually no change in water bird visitation over roughly the same period.

Though many of the South Bay’s salt ponds are being converted to tidal marsh, some will be left intact to support ground-nesting birds. (joSon/bioGraphic)

And though they haven’t experienced a similar surge, western snowy plover populations have held steady thanks to habitat enhancements, including spreading oyster shells on dried salt ponds for improved camouflage and removing nearby perches used by predatory raptors.

The SBSPRP was restoring balance to the South Bay wetlands. But has, the weight of climate change been threatening to tip scales back out of whack. To ensure their progress would not be undone, the project leaders had to start planning not only for what the wetlands needed today, but for what they will need in the near future.

‘A fighting chance’ as bay waters rise

As I stand on one of the easternmost levees of Ravenswood, an open space preserve along the shore of the South Bay and one of three main restoration sites for the SBSPRP, it’s easy to grasp the Bay Area’s vulnerability to climate change. Within a 7-mile radius of me, over largely flat terrain, lies Redwood City, Palo Alto, and Menlo Park, with a combined population of nearly 200,000 people. Water from the bay practically laps at my feet.

According to a recent report from the National Oceanic and Atmospheric Administration, by 2050 sea levels along the West Coast are expected to rise between 4 and 8 inches. At the same time, flooding is expected to become more frequent and severe, with major flood events occurring five times as often.

Dark orange salt pond water in the upper left corner meets a pale gold curve of levee.  On the other side of the levee are the pale and dark brown wetlands, with dark green riparian areas twisting through.
Both levees and wetlands can protect surrounding communities from sea level rise. (joSon/bioGraphic)

While climate change had long been considered by the SBSPRP, Ball says the dire predictions about when the Bay Area could feel its effects — and how severe those impacts could be on people and wildlife — has ramped up the project’s urgency, healthy wetlands can serve as a natural barrier to flooding and storm surges.

The key word, however, is healthy. Even under ideal conditions, it takes time for restored wetlands to go from sparse and fragile vegetation to lush and robust. And rising seas and storms are not ideal circumstances for adolescent wetlands, inundating or robbing the young upstarts of the sediment they need to develop and thrive. The sooner ponds can be breached and restoration started, the more likely it is that the wetlands will be able to mature into a resilient ecosystem. Indeed, a 2019 study from Point Blue Conservation Science, a key partner in the restoration project, showed that if tidal fluctuations weren’t restored to certain parts of the project area by mid-century, they might never accrete enough sediment to survive.

Even mature wetlands will eventually succumb to seas if rates of rising erosion and inundation outpace sedimentation. That is, unless they have somewhere to run.

While plants might appear immobile, over long periods of time plant populations can move in response to their environment. For wetland flora such as salt marsh gumplant (Grindelia stricta) or alkali heath (Frankenia salina), both of which love salty soil but prefer drier conditions, this means extending their roots upland as water levels rise.

A landscape of marsh plants in peach, yellow, cream and brown falls from the upper left to the lower right, meeting a narrow triangle of gray-blue water.  Long, narrow rivers run down the wetland to the bay.
Given time, marsh plants will move upslope or downslope to more suitable soil. (joSon/bioGraphic)

Historically, there was plenty of space for Bay Area marshes to migrate. Gradually sloped transition zones, or ecotones, hundreds to thousands of feet wide, bordered much of the wetlands, providing a spectrum of overlapping habitats from subtidal to salt marsh to upland meadows. Today, development has encroached on 90% of those areas, reducing them in most places to just a handful of feet.

To give the South Bay’s nascent wetlands a fighting chance in the face of climate change, the SBSPRP is adding ecotones to many of their tidal marsh restoration sites during the latest phase of construction. Ecotones aren’t possible everywhere, but they have wide-ranging benefits. In addition to restoring habitat and tempering floods, they can preserve the beauty and accessibility of the wetlands for the region’s human inhabitants.

A pale tan creek winds from the bottom of the image to the upper left corner, through lush green wetlands.  The vegetation on either side of the creek is yellow-green, dark green and brown.
A small creek winds through restored wetlands in San Francisco’s South Bay. (joSon/bioGraphic)

Rather than protecting the Bay Area from floods by building a levee that would turn San Francisco Bay into a giant bathtub, Ball says, ecotones and other nature-based solutions can help “maintain this habitat — even for people.”

A continual cycle of rebirth

On a sunny early afternoon in spring, I visit Eden Landing Ecological Reserve, another of the main project sites for the SBSPRP. At the entrance, a briefly nods to the complicated history of the landscape, no doubt preparing visitors who might soon be confused by the presence of levees, flood control gates, and managed ponds in an ecological reserve. Moments into my walk, however, I feel no confusion: This land is undoubtedly wild.

As I head toward the trail loop, marsh wrens (Cistothorus palustris) burst from the grasses lining both sides of the path, chittering in alarm at my presence before sinking back into the tangle. To my right, a raft of American avocets, heads golden-brown, beaks slightly upturned, bob lazily in a shallow pond. To my left, a long-billed curlew (Numenius americanus) slinks through the tidal mudflats foraging for invertebrates.

Further down the trail, I find myself face-to-face with the full scope of the restoration project. I pass a half dozen ponds of various water levels and shades of yellow, hinting at their differences in salinity. In most, an artificial island emerges a foot or so above the surface. I walk atop levees for most of the journey, occasionally crossing over a floodgate separating pond from pond, or pond from bay. At one of the outermost points from the trailhead I come upon a dried salt bed, a parched moonscape shattered at the edges and scattered with oyster shells.

And at each turn I find signs of life. Goldfinches, yellowthroats and song sparrows flitting through the tall upland grasses. Ducks, herons and egrets along the channels bordering the tidal marshes. Sandpipers, willets, and stilts on the islands of the managed ponds. I even come across an unattended egg nestled atop a patch of clover on the bank of the levee.

I feel grateful for this space, a stone’s throw from busy metropolises and yet a world away. But strangely, I also find myself feeling thankful for the salt ponds — not only those that have been restored and enhanced, but also their human-made predecessors. Almost all of the restorable land along the shores of the South Bay exists because the industrial salt ponds unintentionally preserved this place. If not for the salt ponds, the area would have almost certainly been developed.

The tension between what I know of the land’s tumultuous history and the peace I find there makes me think of joSon. Drawing on his past as a Buddhist monk, the photographer considers the restoration project a form of rebirth, a way of healing the wetlands while reconciling the land’s past traumas.

“The concept of rebirth defines how we grow and redefine ourselves by simultaneously shedding and embracing our painful past,” he says. For him, the arc of the salt ponds’ history offers a way of thinking about how individuals, cultures and places can “adapt and move on.”

Near the end of the trail, I come across the relics of a former salt harvesting operation, retained for posterity. Beyond, wooden pilings worn smooth by tides and time emerging from mudflats and murky ponds, supporting ghost structures no longer present. As the wetlands devour the scars of industry, a semblance of what this landscape once was — and has always been to the Ohlone, who continue to hold ceremonies at shellmound sites — is remerging: a sacred place for plants, animals and people, a wetland in a constant cycle of being reborn.

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