The red knot is the largest of the beach sandpipers, averaging 10.5" in length with a 20-21" wingspan. Its straight, dark, sturdy bill is reminiscent of other sandpiper and shorebird species. Ashen gray and white during the fall and early winter, the knot's true colors emerge with the beginning of the northward migration to their arctic breeding grounds. By the time the flocks reach the Delaware Bay's shores in late April, the edges of their head, neck underside, and underparts are a distinctive reddish-brown and the red band over the eye is particularly evident. The knot's upper body is a darker brown mottled with streaks of reddish-brown, tan and black.
From October to February, a majority of the red knot winter along the coasts of Patagonia and Tierra del Fuego at the southern most tip of South America. The summer breeding season finds the red knot far to the north in the tundra of the low Canadian arctic. The 10,000 mile journey from wintering grounds to breeding sites is one of the natural world's most impressive feats of endurance.
Over the winter season and during migration, red knot rely on shoreline habitat for feeding and resting. The birds forage in intertidal flats. These mud, sand, and sod zones emerge at low tides brimming with life, providing a bouillabaisse of bivalves (mollusks) and crustaceans upon which red knot can feast. In the midst of the breeding season, red knot are found in the low Arctic Tundra. Ground nests are pulled together from lichen, moss, and willow leaves, and are typically found near small tundra wetlands. While the tundra may seem an inhospitable place, the brief summer season provides the knots with an abundance of spiders, insects, and larvae on which to feed and prepare for the voyage south.
While scientists have no firm understanding why the red knot migrate each year, they do know that this species depends on marine worms, clams, mussels, and small crustaceans found along the broad intertidal flats in Patagonia and Tierra del Fuego. This source of food peaks each November through January, while similar food sources along the northeastern United States peak each July and August. Longer daylight hours during these peaks allow the birds greater time to forage. In his comprehensive book, Flight of the Red Knot, author and ornithologist Brian Harrington states that "the single most startling discovery to emerge from my systematic observations of the red knot is the small number of migration-staging areas where feeding, or "refueling" takes place." These staging areas provide rich and dependable sources of food necessary for completing the next leg of the migratory cycle.
Researchers at the Manomet Observatory have used field surveys, aerial overflights, and sophisticated mathematical algorithms to estimate the worldwide red knot population at 250,000±100,000. While pure numbers alone may suggest that the red knot is secure, the picture is far from clear. Brian Harrington explains "customarily, we think of a species as endangered when its population has already been drastically reduced to only a few individuals...for birds like the red knot, however, the scenario for serious trouble follows a different script. The challenge is not to preserve a dwindling number of survivors, but to protect those few pinpoints on the earth that are crucial to the continued existence of hundreds of thousands of birds, perhaps entire populations." Research indicates that the Delaware Bay is one of those "few pinpoints".
Market hunting decimated shorebird populations, including the red knot, in the nineteenth and early twentieth centuries. Today, threats to this and other shorebird species are of a more direct nature. Habitat loss and degradation in key staging areas are primary concerns. Beachfront development, off-road-vehicles and other heavy recreational use of beach areas, conversion and loss of coastal marshlands, and water pollution impact many of the knot's migratory stopover sites. In the Delaware Bay, the looming risk of a major oil spill is particularly threatening. The quality and integrity of the Bayshores as a staging area may also be impacted by declining horseshoe crab populations. Horseshoe crabs, whose eggs provide the bulk of nutrition required to replinish knots during their arduous journey, are thought by many scientists to be in decline, though solid proof has been elusive.
Scientific research has shown the vital importance of migratory staging areas for the conservation of red knot and many other shorebirds. With rich and dependable food resources, the Delaware Bay and a few additional sites provide crucial feeding and resting stopovers, allowing the the shorebirds to refuel sufficiently to complete the next leg of their long migratory journey. TNC's Delaware and New Jersey Chapters are engaged in shorebird protection initiatives on several fronts, including land acquisition (our traditional strength), habitat restoration, public outreach and education, and oil spill response planning. The Delaware Field Office's Milford Neck Nature Preserve provides beachfront and marsh habitat for the migrating red knots that descend upon our state each spring and fall.
Did you know?
In contrast to humans, knots have no need to shuck or shell their catch because their digestive system is able to grind up and process whole shellfish, shell included! Red Knots delight observers with their amazing synchronous flight formations. It is not unusual to see hundreds of feeding knots suddenly take off, rising almost in unison from the beach and maneuvering in undulating waves over land and water before coming to a stop in a new place.
If necessary, a red knot with a fat-free weight of 120 grams can gain as much as 130 grams in a month of feeding, more than doubling its weight.
Red knots renew both their flight and body feathers through the process of molting. Body feathers are replaced twice a year, while flight feathers are renewed once a year during the winter foraging period.May 29, 2013