Animal

Red knot

Calidris canutus rufa

Also known as: Rufa red knot

A medium-sized shorebird (9–10 inches) that performs one of the longest annual migrations on Earth — from wintering grounds in Tierra del Fuego (Argentina/Chile) to Arctic breeding grounds, a round trip of ~19,000 miles. The rufa subspecies depends critically on Delaware Bay as its principal mid-route fueling station: red knots time their northbound spring arrival to coincide with the May/June Atlantic horseshoe-crab spawn, and double their body weight on horseshoe-crab eggs before continuing to the Arctic. Federally listed as threatened. The bay's protection is the single most-important factor in the subspecies' survival.

Scientific

The red knot (Calidris canutus) is a medium-sized shorebird with a circumpolar breeding distribution. The rufa subspecies breeds in the central Canadian Arctic and winters in southern South America, primarily Tierra del Fuego.

Spring migration is staged: red knots fly from Tierra del Fuego to one or more stopover sites in southern Brazil/Argentina, then to a small number of mid-route sites along the Atlantic coast, and finally to Arctic breeding grounds. The total round-trip migration is approximately 19,000 miles annually — one of the longest documented in any bird.

Delaware Bay dependence

The single most important mid-route stopover for the rufa red knot is [[delaware-bay|Delaware Bay]]. Red knots arrive in mid-May, exactly synchronized with the May/June spawning of the [[atlantic-horseshoe-crab|Atlantic horseshoe crab]]. Crabs come ashore by the hundreds of thousands to lay eggs in the sand; red knots feed on the surface eggs intensively for 2–3 weeks, doubling their body weight from ~120g to ~240g.

Without this fattening, red knots cannot make the final flight to the Arctic and successfully breed. The synchronization is absolute: when the horseshoe-crab population was harvested heavily for bait in the 1990s and early 2000s, red knot populations collapsed. Restrictions on horseshoe-crab harvest since the mid-2000s have stabilized but not yet recovered the rufa population.

Conservation

The rufa red knot was federally listed as threatened in 2014. [[delaware-bay|Delaware Bay]]‘s beaches, the surrounding NWRs ([[bombay-hook-nwr|Bombay Hook]], Prime Hook, Cape May), and the horseshoe-crab harvest restrictions are the principal conservation interventions. Population trends are slowly improving but remain a fraction of historical numbers.

Sources

[[us-fish-and-wildlife-service|U.S. Fish and Wildlife Service]] rufa red knot status documentation
[[harrington-delaware|Delaware]] Division of Fish & Wildlife — Delaware Bay shorebird program
Manomet Center for Conservation Sciences shorebird research

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