Shoring up Birds: Providing Habitat for Pacific Flyway Migrants
Look, up in the sky — it’s a shorebird!
“I call them ‘superheroes’,” said Matthew Reiter, a scientist with the nonprofit organization Point Blue Conservation Science. “The distance shorebirds travel for their size is fascinating. Research suggests that some species fly more than 6,000 miles without stopping during migration,” he said, adding that some migratory birds travel 12,000 miles every year.
Western sandpipers, for example, migrate in huge flocks along the Pacific Flyway, the north-south sky route for migratory birds that stretches from Alaska to Patagonia. Western sandpipers have a wingspan of 12 inches and weigh only an ounce, and yet every year they fly from Alaska to South America or the Atlantic Coast — and back again. That’s why the website for the Western Hemisphere Shorebird Reserve Network (WHSRN) describes shorebird migrations as the “endurance marathons of the natural world.”
“Super athletes need to get supercharged,” said Reiter, “and the San Francisco Bay hosts more migrating shorebirds than any other coastal site in the United States.”
Even though 85 percent of the wetlands ringing the San Francisco Bay have been filled or developed, more than 900,000 shorebirds use the Bay and its wetlands for a rest stop or as a place to over-winter. The shorebirds’ reliance on the San Francisco Bay raises the importance of restoring wetlands as sea levels rise and inundate the tidal mudflats that are vital for these migrating superheroes.
San Francisco Bay is ranked as a “Site of Hemispheric Importance” within WHSRN, a network that includes 15 countries and 36.9 million acres of shorebird habitat. Scientists started the network in the 1980s as a strategy to conserve habitat across the Americas for hemispheric migrants.
These birds on the fly have only a few estuaries where they can rest, and for the most part those places are highly urbanized, explained Andrea Jones, director of bird conservation at Audubon California, which protects birds and their habitats. As a result, the migrants contend with pollution, shipping traffic, rip rap and wetland hardening, oil spills, and invasive species that impact natural systems.
The birds also face habitat loss along their route, such as when coastal and estuarine land gives way to tourism and industry in coastal Southern Mexico and Peru. “Birds are facing stopover losses in quality and quantity from day to day, and as a result are having to fly farther for rest and fuel. That raises the importance of the San Francisco Bay being able to continue to support birds in large numbers,” said Reiter.
Sea-level rise is another big challenge. A natural tidal system includes transition zones between the open water, intertidal marshes, and dry uplands. Most edges of the San Francisco Bay are hardened with buildings, roads, or rip rap. If the edges were natural, the intertidal zones could shift to the uplands during high tides, episodic storm surges, and gradually rising sea levels brought on by climate change. “There are very few places for that to happen. Mudflats get inundated and there’s no place for the birds to rest and feed,” said Jones.
Jones witnessed firsthand the payoff of providing habitat for shorebirds when she visited the San Pablo Bay National Wildlife Refuge along Sonoma Creek during a king tide last year. She was touring the 400 acres of recently restored tidal marsh habitat, where her organization worked with the Marin-Sonoma Mosquito and Vector Control District and the U.S. Fish and Wildlife Service to dig a network of channels to let the system “breathe” with the tides. Excavators also moved 30,000 cubic yards of soil to build gently sloping marsh transition zones known as living shorelines. These allow vegetation and wildlife to move up at high tides.
Shorebirds took to the area as soon as construction had been completed. “Living shorelines are really important to include in restoration projects so that Mother Nature can absorb sea-level rise,” said Jones, whose organization also enhanced Aramburu Island in Richardson Bay with natural infrastructure. Aramburu Island is a 17-acre manmade wave break that wildlife hadn’t used for years because of its cliff-like shoreline. Drawing on funding from the Cosco Busan oil spill settlement, Audubon California replaced the steep-sided edges with a gentle slope of sand, gravel, and shell substrate to provide habitat for shorebirds and harbor seals, as well as to give wildlife time to transition as sea levels rise.
The challenge of sea-level rise in natural settings is not confined to wildlife. Conservation organizations must deal with the problem, even though the parameters are unknown. A study by the National Research Council predicts that the range of sea-level rise by 2100 could be anywhere between 18 to 66 inches, a difference of four feet.
Point Blue Conservation Science approaches that uncertainty with Climate-Smart Conservation, a concept adapted from the National Wildlife Federation that uses nature-based approaches to reduce greenhouse gasses, enhance natural systems, and improve the abilities of wildlife and people to adapt rapidly.
Climate-Smart Conservation seeks to balance the needs of natural systems, wildlife, and people. As examples, Reiter cited the South Bay Salt Pond Restoration Project, the largest tidal wetland restoration project on the West Coast. Once it has been completed, restored tidal wetlands will contribute to flood management for Silicon Valley and other low-lying urban centers, provide habitat for wildlife, and open recreational opportunities for people to view and enjoy the wildlife.
A bird’s beauty and athleticism can elicit awe and appreciation. Birds also serve another function. “They provide a tangible way to talk about issues that are hard to grasp, like climate change and sea-level rise,” said Jones. “If birds stop showing up somewhere, the bells should go off. They are the canaries in the coalmine.”
Aleta George covers open space for the Monitor.