Horseshoe Crabs' Decline Further Imperils Shorebirds
Friday, June 10, 2005
SLAUGHTER BEACH, Del. -- As recently as five years ago, this stretch of sand was covered with chirping shorebirds, which depended on Delaware Bay as a critical stopover in their arduous spring migration from Tierra del Fuego to the Arctic. But these days, the beach is almost bare, with just a couple of dozen sanderlings and dunlins digging for the horseshoe crab eggs they need to fuel the trip.
Hundreds of thousands of birds used to stop on Delaware, Maryland and New Jersey beaches for a feast they could not find at other stopovers. Consuming as many as 18,000 pearly blue-green eggs a day, birds such as the tiny, rust-colored red knot doubled in size, from 3.5 ounces to 7 ounces, within two weeks.
Over the past two decades, however, the number of crabs has dwindled as they became attractive to commercial trawlers, who sell the prehistoric creatures as conch and eel bait and for their unique blue blood, which is used medically to detect pathogens. The decrease in spawning crabs, in turn, has contributed to the collapse of bird populations such as that of the tiny rust-colored red knot, which has declined from 100,000 two decades ago to 13,315 last year.
The intertwined fate of Delaware Bay's ancient horseshoe crabs and the red knots is a story of sex, gluttony and death that -- for now -- appears headed for a grim ending. It is also a tale of how quickly an ecosystem can unravel, and how difficult it can be to restore it.
The battle to reverse the trend began in 1998 and will intensify in the coming months as birders seek to place the red knot on the federal endangered species list. Giving it protected status -- the red knot is already considered threatened by New Jersey authorities, but the U.S. Fish and Wildlife Service is still reviewing the case -- could trigger limits on beach access, shoreline development and fishing that could infuriate local commercial interests. Just yesterday, New Jersey officials suspended hand-harvesting of the crabs for two weeks as an emergency measure to try to bolster the birds' food supply.
In an interview, Interior Secretary Gale A. Norton said her deputies are examining whether to take quick action on the red knot, bypassing the department's usual procedures for listing threatened species. It can take 20 years or longer to get a species listed; in this instance federal officials estimate they could make a decision within 18 months.
"We have, on occasion when a species is in a very serious situation, taken some emergency action," Norton said.
New Jersey's and Delaware's top environmental officials said two weeks ago that they plan to ask the administration to list the red knot as an endangered species. John Hughes, who heads Delaware's Department of Environmental Protection, said recent population counts showed "all the evidence of a death spiral" and added: "Without a question, this is a role for the federal government to play, and the sooner the better."
This spring, bird experts from around the globe converged on the bay to try to help save the shorebirds from extinction.
"You don't have international ornithologists coming here because it's the Riviera," said Eric Stiles, vice president for conservation and stewardship at New Jersey Audubon Society. "It's the Riviera of shorebirds -- there's an ecological implosion on this stopover in the Delaware Bay."
Larry Niles, chief biologist for the New Jersey's Department of Environmental Protection's Fish, Game and Wildlife Division, predicts the Western Hemisphere's red knots may go extinct by 2010 if current population trends continue. And other vulnerable species, such as the threatened Atlantic loggerhead turtles that feed on horseshoe crabs during the summer, may also suffer.
All the Delaware Bay shorebird populations are declining, including sanderlings and dunlins, but the red knots are most vulnerable. Unlike other birds, they cannot dig for horseshoe crab eggs, so they need a superabundance to get enough. They also have the longest journey to make each year.