A Semi-Annual Publication of Manomet

WETLANDS: Holding Ground for Shorebirds
By: Haley Jordan

The Semipalmated Sandpiper (Calidris pusilla) is a small shorebird that migrates up to 10,000 miles in the course of a single year. Remarkably, it is small enough to fit in your hand and weighs about as much as a slice of bread.

Semipalmated Sandpipers, like most other shorebirds, depend on wetland areas throughout their lives. They breed in Arctic wet sedge or heath tundra, make stopovers at coastal and inland wetlands, and spend their winters along sandy beaches, intertidal flats and salt marshes in Central and South America.

Red Knots on migration. Photo: Brad Winn

A Semipalmated Sandpiper may stop at just three or four sites to rest and refuel on its marathons to and from its ancestral Arctic breeding grounds. Most travel very specific migration routes, making pit stops at food-rich spots such as Delaware Bay and the Bay of Fundy in eastern Canada. The birds arrive at these migratory staging areas thoroughly depleted and spend weeks foraging to build the fat reserves necessary to complete their migrations and breed successfully.


A Semipalmated Sandpiper with its chick on its Arctic breeding grounds. Photo: Brad Winn

While the wetland habitats that Semipalmated Sandpipers and other shorebirds utilize come in many forms—like marshes, wet meadows, prairie potholes, rice farms, beaches, and bogs—they are all transitional zones between aquatic and terrestrial habitats where water is present at least some of the time. They have unique soils, support vegetation that is specially adapted to wet conditions, and often experience a seasonal flooding cycle.

"Shorebirds are wetland specialists," said Brad Winn, Manomet's director of shorebird habitat management. "They have narrow habitat and food requirements, with most foraging shorebirds preferring to feed on invertebrates like worms, snails, clams, crabs, and shrimp on wet sand, in mud, or in shallow water up to a few inches deep. This limits them to just a small number of highly productive migratory stopover sites that they tend to return to year after year. Shorebirds' dependence on relatively few areas for their reproductive success and survival make them highly vulnerable to habitat loss and degradation at those sites."

While we now know that wetlands play a crucial role in supporting shorebirds and many other species, in the not-so-distant past, these habitats were disregarded or destroyed wholesale. Less than half of North America's original wetlands now remain, and with this dramatic loss of habitats, populations of many shorebird species have declined severely. Some shorebirds —including Semipalmated Sandpipers wintering on the northern coast of South America and the rufa Red Knot—have declined by as much as 80 percent in the past three decades.

Conservation and restoration efforts have slowed rates of wetland loss in recent years, but wetlands continue to be lost and degraded at an alarming rate.

American Oystercatchers rely on coastal wetlands with rich food resources throughout the year.
Photo: Brad Winn.

Found on every continent except Antarctica, wetlands are among the most productive ecosystems on the planet and are highly valuable for the ecological services they provide. However, recognition of this has only come recently.

"Wetlands were historically seen as swampy areas which were only good for their potential conversion to 'usable' land," Winn said. "Wetlands around North America were rapidly drained and filled. Coastal wetlands were widely developed, and interior wetlands were drained primarily for agricultural uses."

According to the U.S. Geological Survey, approximately 53 percent of the original wetlands in North America were lost between 1780 and 1980. Twenty-two states have lost at least 50 percent of their original wetlands, and California and Iowa have lost nearly 99 percent. Globally, over half of all wetlands have been lost since 1900.

When wetlands are destroyed, the benefits they offer to wildlife and people disappear. In addition to providing valuable wildlife habitat, wetlands help regulate natural water levels, provide flood control, and filter excess nutrients and pollutants. Some types of coastal wetlands also sequester and store large amounts of carbon. According to the EPA, wetlands provide an essential link in the life cycle of 75 percent of commercially harvested fish and shellfish and up to 90 percent of the commercial fish catch.

It was not until the 1970s that the vital role of wetlands started to gain recognition. International concern about wetland loss led to an intergovernmental treaty called the Ramsar Convention on Wetlands of International Importance. Signed in 1971, the Convention provides a global framework for the conservation and wise use of wetlands.


Manomet Scientist Brian Harrington first launched the International Shorebird Survey (ISS) in partnership with the
Canadian Wildlife Service in the 1970s.
Photo: Dave Twichell

A few years later, Manomet Scientist Brian Harrington and the Canadian Wildlife Service launched a pioneering citizen science research effort called the International Shorebird Survey (ISS), which led to important discoveries about shorebirds and their dependence on specific wetland habitats.

The ISS was launched in 1974 as a network of volunteers across the Western Hemisphere from Alaska to Patagonia to gather information on shorebirds. Data gathered by ISS volunteers identified critical stopover and wintering sites for shorebirds, and combined with several other research efforts, showed that about half of all shorebird species found in North America have experienced population declines since the early 1970s.

"Through ISS data, we were able to identify important migratory staging sites and determine which species concentrated the most at stopovers," Harrington said. "That information showed us that conservation efforts needed to focus on these key sites to protect shorebird habitats and reverse population declines. About 70 percent of the shorebirds counted by ISS volunteers were at wetlands."


Manomet's Brad Winn with land managers and wildlife professionals during a shorebird habitat
management workshop in South Texas.
Photo: Brian Harrington

The ISS and other related research efforts led to the formation of the Western Hemisphere Shorebird Reserve Network (WHSRN), an international strategy to protect shorebirds and the areas important to their survival along their migratory paths. WHSRN now has 89 sites in 13 countries from Alaska to the southern tip of South America, conserving more than 32 million acres of shorebird habitat.

Federal conservation and restoration efforts have also helped stem wetland loss in the United States. The North American Wetlands Conservation Act provides matching grants to organizations and individuals carrying out wetlands conservation projects for the benefit of wetlands-associated migratory birds and other wildlife. The projects have affected 27.5 million acres of wetland migratory bird habitat in the U.S., Canada, and Mexico.

"These grants are critical to maintaining the health and vitality of America's wetlands and the abundance and variety of wildlife they support," said Fish and Wildlife Service Director Dan Ashe in a recent news release. "Wetlands are particularly crucial to migratory birds all along their flyways."

These efforts have led to significant wetland conservation gains but have not yet reversed the trend. Between 2004 and 2009, coastal wetlands in the continental U.S. were lost at an average rate of about 80,000 acres per year, according to the U.S. Fish and Wildlife Service's most recent report to Congress on the status of wetlands.

"Wetlands are at a tipping point," said former Secretary of the Interior Ken Salazar in a news release following the release of the most recent USFWS report. "While we have made great strides in conserving and restoring wetlands since the 1950s when we were losing an area equal to half the size of Rhode Island each year, we remain on a downward trend that is alarming."

On North America's coastlines, natural wetland ecosystems are scarce and development pressures heavy. According to NOAA, in 2010, over 123 million people (or 39 percent of the nation's population) lived in counties directly along the shoreline, a population which is expected to increase by 8 percent by 2020.

Global sea levels are projected to rise by about two feet by 2100, and the increased frequency and intensity of coastal storms predicted to occur with climate change will increase risks of flooding and property damage.

A growing coastal population also places increasing pressure on shorebirds and their habitats.

"On the coast, shorebirds are particularly tied to natural inlets with shoals that are exposed to the air at low tide," said Winn. "These wet sands provide the food the birds depend on. About 60 percent of the U.S. Atlantic shoreline has been stabilized or otherwise altered, often to the detriment of shorebird habitat."

Inland wetlands continue to face different pressures. Competition for water resources can be fierce in drought-prone agricultural areas, leading to groundwater withdrawal for irrigation, diversions that reduce water flow, and alteration of vegetation. These changes can make it much more difficult for both resident birds and those migrating through to find suitable places to forage and rest. California's Central Valley, which supports 60 percent of the ducks and geese and 30 percent of the shorebirds on the entire Pacific Flyway, is experiencing one of the worst droughts in its history this year.

In the face of these challenges, Manomet scientists are working to relieve the impacts of wetland loss on shorebirds by creating suitable habitat conditions on public and privately managed wetlands through the Shorebird Habitats Project.

"Management of most publicly-owned wetlands in the U.S. can be modified to meet the habitat needs of shorebirds," Winn said. "We are helping land managers make more effective use of land resources by providing them with the tools to make additional habitat available to shorebirds in the right places at the right times during their migrations."

Launched in 2013, the project provides training and technical services to managers of public and privately owned wetlands in the U.S. that are important to shorebirds. These efforts build on a series of Manomet-led shorebird habitat management workshops held in the late 1980s and early 1990s.


Winn and Harrington pose with workshop participants in Texas. Photo: Alberto Martinez

"We hold four-day workshops which cover shorebird identification and ecology, conservation, threats, field censusing methods and management techniques," said Winn. "This program differs from past efforts to incorporate shorebird needs into management protocols because we are establishing on-going relationships to help land managers refine techniques used on the wetlands they manage."

In four years, 500,000 new acres of North American wetlands will be managed for shorebird conservation as a result of the Shorebird Habitats Project.

"Populations of some shorebird species are approaching precariously low numbers," Winn said. "As wetlands in the U.S. and around the world continue to be lost and degraded, efforts to conserve, restore, and more effectively manage wetland habitats can help recover populations of these declining birds."

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