The last call of the rail in California?


Light-footed Ridgway’s Rail (Rallus obsoletus levipes) perched on artificial nesting platform in tidal wetlands at Seal Beach Wildlife Refuge during fall high tide event. Photo credit: Kirk Gilligan – USFWS

When I tell people that I study the vulnerability of salt marshes to sea-level rise in California, the typical responses are “What’s a salt marsh?” or “We have those in California?”. Because most of California’s salt marshes are small, and isolated by development and topography, these questions don’t surprise me. Instead, these questions serve as motivation because it worries me that future generations may only hear the clappering call of my favorite salt marsh bird, the endangered Ridgway’s Rail (Photo 2), in a zoo or as a recording.

Photo 2. California Ridgway’s Rail (Rallus obsoletus obsoletus) hopping out of cordgrass habitat at Arrowhead salt marsh near Oakland, California. Photo Credit: Marcia Grefsrud -CDFW

I encourage fellow Californians as they drive along the coast to stop and notice how the pickleweed shrubs poke out above the high tides at Upper Newport Bay, or how the tidal creeks at Corte Madera marsh, wander through green swaths of cordgrass (Figure 1). 

Figure 1.Location of salt marshes mentioned in the blog.

These roadside salt marshes may seem humble because they don’t awe you like the redwood forests of California, or impress you like the waves of the Pacific Ocean. Still, these Pacific coast salt marshes protect secretive birds and mammals that live at the intersection of land and sea. Compared to the vast monocultures of cordgrass that dominate on the Atlantic and Gulf Coasts of North America, salt marshes of California have a shrub-dominated marsh plain containing interesting native plants, such as alkali heath, fleshy jaumea, and pickleweed, with cordgrass found near the edges of tidal creeks (Photo 3).

Photo 3. Light-footed Ridgway’s Rails at Bolsa Chica. Photo Credit: Steve Smith – HB

Before I began my master’s work in 2010, I admit I also tended to overlook these marsh ecosystems. However, a chance to engage in salt marsh field work as a graduate student changed my perspective. My first visits to Mugu Lagoon and Seal Beach wetlands in California were welcomed escapes from classes at UCLA, but after a few years of research, I also started to understand more fully the characteristics that made these ecosystems unique and highly vulnerable to the effects of climate change and sea-level rise. During a visit in October 2015, a USGS field technician and I were collecting water samples to monitor sea-level rise vulnerability and assess potential impacts of a sea-level rise adaptation strategy. Interestingly, the tides were 6 inches to 1 foot higher than predicted due to El Nino effects, and the temperatures were expected to break 100 degrees – conditions that could be the norm if temperatures track regional climate change and sea-level rise projections. I too began to contribute to the detailed scientific understanding of the sedimentary dynamics of the salt marsh system through my research on sediment fluxes at Seal Beach and Mugu Lagoon.

Photo 4. Light-footed Ridgway’s Rails at Bolsa Chica Salt Marsh – Steve Smith – HB.

As wetland scientists, we are simultaneously trying to understand the effects of climate change and sea-level rise on salt marshes, and also trying to the make them more resilient to such forces. Salt marshes could be the first coastal ecosystems to perish in the wake of climate change and sea-level rise, or they can be a success story of adaptation. In the field, we monitor current and historic accretion rates using soil cores and surface elevation tables to understand how salt marshes respond vertically to sea-level rise changes. We also estimate current elevations with centimeter level accuracy, allowing us to downscale marsh elevation scenarios that are more relevant for individual Rails, and track sediment fluxes (Photo 4) to determine how the salt marshes and tide channels might evolve.

Photo 5. Seal Beach Wetlands. Note that Seal Beach has an extensive amount of cordgrass cover because of low elevations that make it vulnerable to sea-level rise. Photo Credit: UCLA -Amanda Wagner

Recent habitat suitability projections for 14 individual salt marsh sites in the San Francisco Bay Area and Southern California show that 90% of the current breeding habitat for two coastal Ridgway’s Rail sub-species could be lost by 2110 under a sea-level rise rate of 1.66m/100yr. While salt marshes like Laumeister in the South Bay of San Francisco Bay Area may have adequate sediment supply and elevation capital to keep pace with local sea-level projections, low elevation salt marshes with urbanized watersheds like Seal Beach wetlands may be on the brink of collapse. Conservation of breeding season habitat for salt marsh obligate species, like Ridgway’s Rails, in the face of sea-level rise may involve short-term strategies, such as deploying nesting platforms, and long term measures, such as adding sediment to the marsh plain. While we expect the loss of breeding habitat to have catastrophic effects on the species in the long term, loss of high tide refuge habitat in the near term, due to coastal squeeze, may only speed up these predicted extirpations. Thus, if we want future generations to be able to hear the call of the rail in the wild, the time to plan adapt is now!

Photo 6. The author collecting a water sample at sediment augmentation site to estimate suspended sediments at Seal Beach Wetlands. Photo Credit: Amanda Wagner – UCLA
Photo 7. Light-footed Ridgway’s Rail (Rallus obsoletus levipes) inartificial nesting platform in tidal wetlands at Seal Beach Wildlife Refuge during fall high tide event. Photo credit: Kirk Gilligan – USFWS

Jordan Rosencranz is a Southwest CSC Fellow and further affiliated with the Environmental Science and Engineering Program at UCLA as well as the USGS Western Ecological Research Center at the San Fransisco Bay Estuary Field Station. His research interests include monitoring the vulnerability coastal wildlife species and habitats to climate change and sea-level rise, and understanding the effectiveness of different sea-level rise and climate change adaptation strategies.

Additional Resources:

Casazza ML, et al. 2016. Endangered species management and ecosystem restoration: finding the common ground. Ecology and Society 21:19.

National Resource Council 2012. Sea-Level Rise for the Coasts of California, Oregon, and Washington: Past, Present, and Future. The National Academies Press, Washington D.C.

Overton C, Casazza M, Takekawa J, Strong D, Holyoak M. 2014. Tidal and seasonal effects on survival rates of the endangered California clapper rail: does invasive Spartina facilitate greater survival in a dynamic environment? Biological Invasions 16:1897-1914.

Rosencranz J, Ganju N, Ambrose R, Brosnahan S, Dickhudt P, Guntenspergen G, MacDonald G, Takekawa J, Thorne K. 2016. Balanced Sediment Fluxes in Southern California’s Mediterranean-Climate Zone Salt Marshes. Estuaries and Coasts 39:1035-1049.

Rosencranz J, Thorne K, Buffington K, Overton C, Takekawa J, Casazza M, McBroom J, Wood J, Nur N, Zembal R, MacDonald G, Ambrose R. Availability of breeding season habitat for two coastal California Ridgway’s Rail (Rallus obsoletus) sub-species under potential sea-level rise scenarios. In preparation.

Swanson K, Drexler J, Schoellhamer D, Thorne K, Casazza M, Overton C, Callaway J, Takekawa J. 2013. Wetland Accretion Rate Model of Ecosystem Resilience (WARMER) and its Application to Habitat Sustainability for Endangered Species in the San Francisco Estuary. Estuaries and Coasts 37:476-492.

Takekawa JY, Thorne KM, Buffington KJ, Spragens KA, Swanson KM, J.Z. D, Schoellhamer DH, Overton CT, Casazza ML. 2013. U.S. Geological Survey Open-File Report: Final report for sea-level rise response modeling for San Francisco Bay estuary tidal marshes.

Thorne KM, Takekawa JY, Elliott-Fisk DL. 2012. Ecological Effects of Climate Change on Salt Marsh Wildlife: A Case Study from a Highly Urbanized Estuary. Journal of Coastal Research 28:1477-1487.

Veloz SD, Nur N, Salas L, Jongsomjit D, Wood J, Stralberg D, Ballard G. 2013. Modeling climate change impacts on tidal marsh birds: Restoration and conservation planning in the face of uncertainty. Ecosphere 4:1-25.

Zhang H, Gorelick SM. 2014. Coupled impacts of sea-level rise and tidal marsh restoration on endangered California clapper rail. Biological Conservation 172:89-100.

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