The Red Knot

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The red knot (Calidris canutus), a robin-sized shorebird, is most commonly seen foraging for small clams, mussels and other invertebrates on our south shore beaches during its spring and fall migration. It is one of the last shorebirds to arrive here in spring, with numbers peaking during the last week in May. Its late arrival coincides with two other high Arctic nesters, the sanderling and the ruddy turnstone.The high Arctic’s short summer means that these birds have a small window to mate, build nests, incubate eggs, and fledge chicks. All those tasks are completed by mid-July. Females leave first, passing through here by late July; newly fledged young don’t arrive until late August. Peak numbers of red knots on Long Island during their “fall” migration are recorded while it is still summer, between July 24 and August 26.

The red knot could be considered a poster child for the problems and challenges that wildlife conservationists face. With important wintering areas found as far south as Tierra del Fuego, nesting areas in the high Arctic, and crucial migratory feeding areas found in several locations between the two, long-term conservation of this species requires international cooperation.

Its survival is also closely linked to the protection of the horseshoe crab, whose eggs fuel the last leg of its long-distance migratory flight from Delaware Bay to its high Arctic nesting sites north and west of Hudson Bay, Canada (the first red knot nest was documented in 1909 by members of Admiral Perry’s North Pole expedition).

The subspecies that visits Long Island during the spring and fall migrations is “rufa,” and despite several important conservation initiatives to protect the rufa red knot, the U.S. Fish and Wildlife Service recently announced that it is being considered for federal “threatened” status under the Endangered Species Act.

Ornithologist John Bull, in his classic work “Birds of the New York Area,” published in 1964, writes that red knots were reported on Long Island’s south shore beaches during migration “by the thousands” before 1890. That changed dramatically as a result of unregulated sport and market shooting of the large flocks, with some reports of harvests totaling thousands of birds.

The Migratory Bird Treaty Act, enacted in 1918, put an end to the slaughter of many of our native birds in Mexico, the United States and Canada, and by the 1930s the rufa red knot population had recovered significantly, although it would never reach pre-1890 numbers. And Long Island and Cape Cod never regained the large numbers of spring migrants that had been noted in the 1800s.

The fact that sport and subsistence hunting of shorebirds is still practiced in South America and many Caribbean islands gained much attention in 2011, when two whimbrels, bearing satellite transmitters and a red knot banded in Delaware six years earlier were shot. The island of Guadeloupe in the French West Indies has an estimated 3,000 hunters; some may harvest as many as 500 to 1,000 shorebirds in a single year!

Fortunately, the red knot bearing the leg band “B95” has so far avoided being shot. Banded at its wintering grounds in Argentina in 1995 when it was at least 2 years old, B95 has now logged enough miles to make it to the moon and partway back, earning it the nickname “Moonbird.”

Wildlife biologists studying the red knot in the 1970s through the 1990s provided important data to establish shorebird reserves at key wintering areas in South America, nesting areas in Canada, and important migratory staging areas in the United States. However, these positive steps were undermined by a dramatic increase in commercial harvest of horseshoe crabs for bait (eel and whelk) and the biomedical industry from 1990 to 2000.

Delaware Bay is one of five key migratory stopover sites for New World shorebirds. An estimated 80 percent of the entire North American shorebird population stops at one of these five sites during spring migration. The other four sites are the Bay of Fundy, Cheyenne Bottoms (Kansas), Gray’s Harbor (Washington), and the Copper River delta (Alaska). In 1995, biologists documented the barrier islands on the coast of Virginia as another important stopover area for 30 percent of the rufa red knot population.

Horseshoe crab eggs are an energy-rich and historically super-abundant food for red knots and other shorebirds. Surveys revealed that 1.5 million shorebirds visit Delaware Bay over one month in May en route to their nesting grounds. After two weeks of fattening up on eggs, red knots can make the 2,000-mile flight to the high Arctic without stopping to refuel!

Horseshoe crab harvest reductions were implemented in 2001, and New Jersey established a complete moratorium in 2006, reducing horseshoe crab harvest levels by more than 75 percent. At the same time, red knot surveys at their main migration staging area on Delaware Bay and a key wintering area at Tierra del Fuego over the years 2002 to 2008 revealed that their population plummeted by 75 percent compared to 1980 numbers. It appears that horseshoe crab numbers at Delaware Bay have not rebounded well, leveling off in 2005 after a brief recovery.

Meanwhile, Moonbird is at least 20 years old and flies on. He was sighted in early August 2013 on an island in the St. Lawrence River, Canada, en route south to Tierra del Fuego, having survived another breeding season.

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