Species → Red Knot
Red Knot
Calidris canutus
What if it disappeared?
Impact HighThe harvest of horseshoe crabs for bait increased 10-fold during the 1990s, causing a more than 90% drop in the availability of their eggs on Delaware Bay beaches — the red knot population stopping there in spring declined by more than 75% between 1997 and 2007.
DocumentedDetail
Niles, L.J. et al. (2009). Effects of Horseshoe Crab Harvest in Delaware Bay on Red Knots: Are Harvest Restrictions Working? BioScience, 59(2), 153–164.
Delaware Bay hosts between 50 and 80% of the entire rufa subspecies each spring, where the birds stop to rebuild, in just a few weeks, the fat reserves needed for the final leg of their migration to the Arctic — a dietary link so tightly bound to a single resource, in a single place, at a single moment of the year, that its partial disappearance was enough to collapse the whole population.
The Tierra del Fuego wintering population fell from 51,000 to 27,000 individuals in just two years, with adult annual survival dropping 37% in a single season and the number of young recruited into wintering flocks falling 47%.
DocumentedDetail
Baker, A.J. et al. (2004). Rapid population decline in red knots: fitness consequences of decreased refuelling rates and late arrival in Delaware Bay. Proceedings of the Royal Society B, 271(1541), 875–882.
By tracking bird weights at departure from Delaware Bay, the authors show that a growing proportion of birds no longer reached the 180 to 200 g threshold weight needed to complete the flight to the Arctic without difficulty — directly linking, step by step, an egg shortage on a single North American beach to a measured population collapse wintering at the opposite end of the continent.
The red knot is presented as an umbrella species whose protection would benefit all the shorebirds sharing its migratory stopovers — but no study measures what would specifically be lost, for those other species, if the red knot itself were to disappear.
InsufficientDocumentation
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IUCN Red List — Calidris canutus, statut de conservation
Accessed August 14, 2026
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Niles et al. (2009) — Effects of Horseshoe Crab Harvest in Delaware Bay on Red Knots: Are Harvest Restrictions Working?, BioScience
Accessed August 14, 2026
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Baker et al. (2004) — Rapid population decline in red knots: fitness consequences of decreased refuelling rates and late arrival in Delaware Bay, Proceedings of the Royal Society B
Accessed August 14, 2026
Last verified: August 14, 2026