Shorebirds in Decline: The Tale of the Least Sandpiper and Semipalmated Sandpiper
By Joe Reynolds, Exc Director of Save Coastal Wildlife
It’s a warm evening in May. I am standing along the edge of the ocean at the Sandy Hook Unit of Gateway National Recreation Area in New Jersey. It’s an approximately seven mile-long and one-mile wide (at its widest point) narrow spit of land at the southern entrance to New York Harbor. A slender sandy peninsula that forms a natural boundary between the deep waters of the Atlantic Ocean and shallow estuarine waters of Sandy Hook Bay.
This narrow piece of land that early Dutch settlers in the1600s called “Sant Hoek,” meaning a sandy corner, angle, or fishhook, is like no other! In view of towering skyscrapers and the Verrazano Bridge of New York City, Sandy Hook contains some of the last remaining coastal characteristic ecosystems around New York Harbor, including maritime forests, freshwater coastal ponds, tidal flats, broad sandy beaches, and saltwater wetlands. They exist all together like an oasis amid one of the most urban-suburban coastlines in America.
Decades of poorly planned development have left much of the coast with few natural areas, not just in New Jersey, but also over much of New York and the highly populated northeast and mid-Atlantic. Ian L. McHarg, the eminent landscape architect and writer, described in his admired 1969 ecological planning book entitled, Design with Nature, the plight of people to not sustain nature within or around modern urban and suburban areas as a source of life is foolish. He writes, “I need not look far for we have seen them – the hot dog stands, the neon shill, the ticky-tacky houses, dysgenic city and mined landscapes. This is the image of the anthropomorphic, anthropocentric man; he seeks not unity with nature but conquest.” Words that were true 50 years ago are still true today. Many people endeavor to subjugate nature to the will of a single species, the human species. “Refine they may,” McHarg asserts, “but refined they are not.”
Fortunately all is not lost. A surprising number of extensive parks and wildlife preserves have been established over the years thanks in large part to the hard work of countless leaders in government and business; and from the hard work of nonprofits and volunteers. Sandy Hook, Jamaica Bay, Fire Island, Island Beach State Park, and a grand assortment of others protected natural places are able to extend a shielded location from the reach of people trying to convert land for short-term needs. These and other parks and preserves provide critical habitat to maintain ancient systems and activities that have taken place over thousands of years for a diversity of coastal wild plants and animals to feed, grow, rest or raise a family.
Yet, even among these protected urban wilds or sanctuaries near subways, roadways and parking lots, it’s not flawless or picture perfect. Water and air pollution still exist, solid waste management is an ever-growing problem, lowered biodiversity from access roads and recreation continues, and the effects of global climate change seem to be linked to all of these troubles. It’s a tough life for coastal plants and animals to thrive, let along survive. Even more so now as many plants and animals have to compete for space and resources with a human population that is multiplying quickly along or near the coast. Over 50 million people live in the Northeast megalopolis between the cities of Boston and Washington D.C. It’s the most heavily urbanized agglomeration in the United States.
Birds often provide the most conspicuous and sometimes the most numerous sight of wild nature for people in urban and suburban areas. With springtime migration providing a particularly wonderful time for bird watching. Everything seems on the move. Epic journeys take place over several weeks, as migratory birds are anxious to reach their breeding grounds, begin mating and raise young.
For migratory shorebirds, their springtime journey is possibly the most dramatic of all bird migration stories. Shorebirds are some of the world’s greatest travelers, undertaking spectacular long-distance migrations. Several species of shorebirds will fly countless miles each year from their nesting grounds in the Arctic to winter in Central or South America, and then return to the Arctic the following spring. Some fly at altitudes exceeding 10,000 feet, and fly over 9,000 miles during migration and achieve cruising speeds approaching 50 mph.
Two migratory shorebirds that seem to be having a particularly hard time surviving in the modern world are the Least Sandpipers (Calidris minutilla) and the Semipalmated Sandpipers (Calidris pusilla). Both bird populations are decreasing.
The International Union of Conservation of Nature and Natural Resources (IUCN) has listed the Least Sandpiper as a species of “Least Concern,” but with a population trend that is decreasing. The news is even worse for the Semipalmated Sandpiper. The IUCN lists this bird as “Near Threatened,” with a population trend that is also decreasing.
The Least Sandpiper is the smallest member of the sandpiper family, no larger than a sparrow. These petite birds make a rather long journey of thousands of miles from as far away as northern South America mostly over the open ocean to reach meadows and bogs of the tundra in eastern Canada. People living along the east coast of the United States often see Least Sandpipers in small flocks, resting and feeding inland alongside small bodies of water, including ponds, puddles, and even along the edge of sewage treatment pools to feed on small crustaceans (amphipods and isopods), insects, and snails.
The Semipalmated Sandpiper is likewise a small sandpiper, a little bit larger than a sparrow, with a short neck and a small head. The word “semipalmated” refers to slim webbing between their toes, which is only visible at extremely close range. The bird migrates in flocks and makes a long flight of 2,000 miles or more from the coast of South or Central America or the Caribbean to low Arctic tundra in eastern Canada or Alaska. They stop along the way at Delaware Bay or other coastal/estuarine sites to feed on horseshoe crab eggs and on tiny aquatic insects, worms, and crustaceans.
Both birds at one time used to frequently gather in large numbers, sometimes by the hundreds or thousands especially for the semipalmated sandpiper, at numerous stopover points in the northeast during spring migration. Nowadays, populations are decreasing. Extensive habitat loss along the coast has made these shorebirds dependent on just a few key stopover points to rest and feed.
But what happens when there is not enough open spaces or not enough food at these stopover locations to supply the nutrient requirement for the birds to continue their migration? Science provides some answers.
In a March 2012 journal article entitled, “Energetic Condition of Semipalmated and Least Sandpipers during Northbound Migration Staging Periods in Delaware Bay” by David S. Mizahi and others published by Waterbird Society, the authors show that food availability plays a significant role in the health of these birds during migration. While in Delaware Bay during springtime migration between 1995 to 1997 and 2000 to 2008, Semipalmted Sandpipers fed primarily on horseshoe crab eggs, but harvest pressure on horseshoe crabs for bait from 1995–2005 dramatically reduced egg availability. As a result, many birds couldn’t find enough food to continue their northbound migration. Least Sandpipers, on the other hand, were less dependent on horseshoe crab eggs, so they were able to feed and gain enough energy to continue their migration northward.
More than 10 years later, things have not gotten all that much better for the Semipalmated Sandpiper. Population trends by the IUCN suggest the bird has declined significantly since the 1980s, especially populations migrating along the Atlantic Coast to eastern Canadian breeding areas, which could be related, in part, to changes in food availability in Delaware Bay.
Habitat loss along the east coast is also a factor. This idea is backed up by a 2017 scientific paper entitled, “Migratory connectivity of Semipalmated Sandpipers and implications for conservation,” written by Stephen Brown and others, published in The Condor. Brown and his colleges found that the winter Semipalmated Sandpiper population in northeastern South America is decreasing dramatically. Brown states: “The eastern population has plummeted by 80 percent in South America and faces multiple threats throughout its migration and lifecycle. As sandpipers, which each weigh no more than two AA batteries, fly north along the eastern seaboard of the United States, they may feel the severe impact of long-term losses in wetland habitat due to development along the coast.”
For Least Sandpipers, their decline is subtler, but is also in large part due to habitat loss. According to the Cornell Lab of Ornithology, a 2012 study estimates a continental population of 700,000 birds. Although this sandpiper species appears widespread and numerous, populations are slowly in decline especially in eastern North America. The Cornell Lab of Ornithology tells us “between 1974 and 1991, the fall migration count for Least Sandpipers in eastern Canada fell by 3 percent per year. The Maritime Provinces population dropped by 15.8 percent annually from 1974–1998. Because their breeding range is broad and remote, it’s likely the declines are happening at other points in their life cycle, such as from losses of wetland habitat on their migration routes and wintering grounds.”
According to an analysis of data from the International Union for the Conservation of Nature (IUCN), habitat loss is the number-one threat to biodiversity worldwide. In the northeast United States, we have lost a lot of natural coastal habitat, including wetlands, from the development of roads, bridges, homes, and shopping centers. According the USDA Natural Resources Conservation Service, a scientific study tracked wetland changes between 2004 to 2009 in the coastal watersheds of the Pacific, Atlantic, and Gulf of Mexico as well as the Great Lakes. It concluded that more than 80,000 acres of coastal wetlands are being lost on average each year, up from 60,000 acres lost per year during the previous study from 1998-2004. In the Northeast region, urban and suburban development is the primary reason wetlands are drained with the loss of 100,000 acres between 1992 and 2010.
The loss of wetlands in the northeast has had a negative ripple effect on providing places for migratory shorebirds to feed and rest. There are simply not enough wild places for shorebirds to relax and find food during migration.
Writer John Hurdle in a May 12, 2016 article in the New York Times entitled, “The Shorebirds of Delaware Bay Are Going Hungry,” shows us that everything is connected in nature, including how people treat the environment. Take one thing away and other aspects of nature suffer. “Overfishing of horseshoe crabs for commercial fishery bait and the harvesting of the animals for their blood, which contains an extract called L.A.L., used by the biomedical industry to detect certain bacteria” has lead the way to declining shorebird populations. The Red knot (Calidris canutus) “has been listed as a threatened species. Since 2000, Red Knot numbers have plunged as low as 10,000 in some years, around one-ninth of the level in the 1980s. At the moment, the population hovers at about 30,000, still too low to be sustainable.” Life is still not easy for shorebird migration. How much longer can they hang on is anyone’s best guess?
While walking the beach at Sandy Hook, I often like to visualize a future where people plan and produce an increasing, not diminishing number of parks and nature preserves and urban wild areas along the coast. Here people can observe the real wonders of the world not built by the human species, including springtime bird migration.
Over centuries, a priority for many people has been to control, change and destroy the natural world for the short-term. Now we need another goal - to preserve habitat and save wildlife. If we can learn to live with wild animals and respect their habitat then this undoubtly ensures that both animals and humans have a healthier future ahead.
We can lean from others in how to accomplish such a great hope. Take for example Ian L. McHarg one more time. In concluding his book, Design with Nature, he writes, “In the quest for survival, success and fulfillment, the ecological view offers an invaluable insight. It shows the way for the man who would be the enzyme of the biosphere – its steward, enhancing the creative fit of man-environment, realizing man’s design with nature.”