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Will Red Knots Soon Be 'Endangered'?

The lives of two unlikely creatures – an ancient "living fossil" called the Horseshoe Crab and a delicate shorebird called the Red Knot – are intimately intertwined. So are their futures, and the future doesn't look good.

Lawrence Niles, Ph.D., chief of the Endangered and Nongame Species Program of the New Jersey Division of Fish and Wildlife, told a Delaware audience that the Red Knot is likely to be listed as "endangered" in the near future.

Image:  Red Knot shorebird, photo © by Frederick W. Fallon
Red Knot
Photo by Frederick W. Fallon
His remarks came at a Horseshoe Crab Workshop sponsored by the Delaware Department of Natural Resources and Environmental Control (DNREC) in Dover on February 5, 2003.

A recent Red Knot study by major shorebird experts from around the world examined the Red Knot population in the entire Delaware Bay, including Delaware and New Jersey. Projections from the study suggest that the Red Knot could become extinct as early as 2010, according to Dr. Niles.

Why is the Red Knot so threatened?

It all starts in the Delaware Bay, the largest spawning area in the world for the ancient Horseshoe Crab. Every May, the Horseshoe Crabs come to Delaware Bay beaches to lay their eggs. At the same time, shorebirds – including the Red Knot – use the Delaware Bay beaches as a food stop on their annual migration from South America to the Arctic.

According to DNREC's Stew Michels several studies have shown declining Horseshoe Crab populations. Although he said the studies "are not definitive," they show a big population drop in the 1990s and fairly stable population numbers for the past four years. He added that "no surveys indicate increasing populations."

Even more important, according to Dr. Niles, there are significant declines in horseshoe crab eggs on the New Jersey beaches.

Delaware Bay is the last stop for the Red Knots en route from their winter home in Brazil to their summer home in the Arctic. The birds arrive at the Delaware Bay beaches at very low weights, he said, lower than at any other stopover. "They have to double their body weight," Dr. Niles said, "and the only nutrient they can use is Horseshoe Crab eggs."

His studies have shown a decline in the birds ability to gain the necessary weight. He said this could be due to later arrivals or to decline in the Horseshoe Crab eggs. He added that the best studies seem to indicate the decline in eggs is the major problem. This results in lower productivity among the birds, and more deaths during the migration. The Red Knot now has a 56% survival rate.

"The number of Red Knots in South America has fallen in half," said Dr. Niles, "and most of the decline has occurred in the past four years." He estimated the current population at between 40,000 and 50,000 birds.

Adding support to his argument, he pointed out that the population of Hudsonian Gotwits, another shorebird that migrates to South America, has remained constant. The Hudsonian Gotwit does not go through Delaware and does not rely on Horseshoe Crab eggs.

David B. Carter, environmental program manager for DNREC's Coastal Programs and a member of the Delaware Shorebird Monitoring Team, presented some preliminary results of Delaware studies on shorebirds. He said their studies show Red Knot populations in Delaware dropping from about 80,000 in 1998 to about 30,000 in 2002.

Mr. Carter added that the largest groups of Red Knots in Delaware now congregate at Bowers Beach and Mispillion Harbor. Because of a proposed marina at Mispillion Harber, he said "We [DNREC] want to make sure we're careful there." He said the DNREC team no longer sees Red Knots using Port Mahon for feeding, possibly because there are too many people too close.

The Horseshoe Crab Workshop was attended by about 75 people, including researchers, academics, students, environmentalists and watermen. The purpose of the workshop was educational. Although comments were allowed at the end, it was not a public hearing.

DNREC officials said they "are considering further restrictions in Delaware this summer" on Horseshoe Crab harvesting.

Several environmental groups, including Delaware Audubon, have recommended a moratorium on the harvesting of Horseshoe Crabs. On March 7, they were joined by the Wilmington News Journal, which editorialized that "There is unrefutable proof that moratoriums on marine harvesting can bring a species back to manageable numbers. ... The annual tweak of harvesting limits has not worked. A moratorium would."

— Report by Fred Breukelman
Delaware Audubon Internet Communications Chair

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This page was last updated on November 20, 2003.