Skilled aviator Rear Admiral RichardE. Byrd flew over both the North andSouth poles. But what this renownedman accomplished with the help of sleddogs, ships and airplanes, a littleshorebird weighing less than a cup ofcoffee completes every year of its life.The red knot is truly a master of long-distance aviation.

On wingspans of 20 inches, some red knotsfly more than 9,300 miles from south tonorth every spring and repeat the trip inreverse every autumn, making this birdone of the longest-distance migrants in theanimal kingdom. About 9 inches long, redknots are about the size of a robin.Biologists have identified six subspecies,three of them living in the WesternHemisphere: C.c. islandica, C.c. roselaari,and C.c. rufa. This last, the red knotknown as rufa, winters at the tip of SouthAmerica in Tierra del Fuego, in northernBrazil, throughout the Caribbean, andalong the U.S. coasts from Texas to NorthCarolina. The rufa red knot breeds in thetundra of the central Canadian Arcticfrom northern Hudson Bay to thesouthern Queen Elizabeth Islands.

Surveys of wintering knots along thecoasts of southern Chile and Argentinaand during spring migration in DelawareBay on the U.S. coast indicated a seriouspopulation decline during the 2000.Biologists from the U.S. Fish and WildlifeService, state natural resource agencies,

and non-profit organizations all share aconcern for the rufa red knot and arepooling efforts to identify what needs tobe done to prevent further losses.

Strength in numbersRed knots winter and migrate in largeflocks containing hundreds of birds.While we can guess at some of thebenefits of traveling in large flocks, suchas protection from predators, we can alsosee the downside - susceptibility tohabitat change and loss, oil spills, toxins,red tides, diseases, collisions with windturbines, storms, and hunting. Red knotswere heavily hunted in the early 20thcentury, and may have never recoveredin eastern North America. Knots are stillhunted in parts of the Caribbean andSouth America.

Eating like a birdFor much of the year red knots eat smallclams, mussels, snails and otherinvertebrates, swallowing their preywhole – shell and all. Migrating knotscan complete nonstop flights of 1,500miles and more, converging on criticalstopover areas to rest and refuel along

the way. In order to endure their longjourneys, red knots undergo extensivephysical changes. Flight musclesenlarge, while leg muscles shrink.Stomachs and gizzards decrease, whilefat mass increases by more than 50percent. Due to these physical changes,knots arriving from long migrationflights are not able to feed maximallyuntil their digestive systems regenerate,a process that may take several days.Thus, migrating birds require stopoverhabitats rich in easily digested foods –with thin or no shells – in order to gainenough weight to fuel the next flight. Inspring, migrating knots seem to follow anorthward “wave” in quality prey – bytiming their stopovers with the spawningseasons of intertidal invertebrates, knotstake advantage of readily digestible foodresources like juvenile clams andmussels and horseshoe crab eggs. Redknots arrive at stopovers areas very thin,sometimes emaciated. They eatconstantly to gain enough weight tocontinue their journeys, adding up to 10percent of their body weight each dayand nearly doubling their body weightsduring some stopovers.

U.S. Fish & Wildlife Service

Rufa red knotCalidris canutus rufa

A red knot banded in May1987 was seen on DelawareBay in May 2000. Duringthose 13 years, the bird hadflown about 242,350 miles, adistance farther than from

the earth to the moon.

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Requirements for survivalThe red knot’s unique and impressive lifehistory depends on suitable habitat, food,and weather conditions at far-flung sitesacross the Western Hemisphere, fromthe extreme south of Tierra del Fuego tothe far north of the central CanadianArctic. Further, red knots need toencounter these favorable habitat, food,and weather conditions within narrowseasonal windows as the birds hopscotchalong migration stopovers betweenwintering and breeding areas. Forexample, the red knot population declinethat occurred in the 2000s was causedprimarily by reduced food availabilityfrom increased harvests of horseshoecrabs, exacerbated by small changes inthe timing that red knots arrived at theDelaware Bay. Red knots may also beparticularly vulnerable to global climatechange, which is likely to affect the arctictundra ecosystem where the knotsbreed; the quality and quantity of coastalhabitats due to rising sea levels; thequantity and timing of invertebrate foodresources throughout the bird’s range;and the severity, timing, and location ofstorm and weather patterns.

Horseshoe crab harvests are nowmanaged with explicit goals to stabilizeand recover red knot populations; redknot number appear to have stabilized inthe past few years, but at low levelsrelative to earlier decades. Red knotsfascinate biologists, bird watchers andpeople who appreciate the complexbeauty of the natural world. Togetherwith these partners, the U.S. Fish andWildlife Service is dedicated to workingto conserve this extraordinary bird.

Northeast RegionU.S. Fish and Wildlife Service300 Westgate Center DriveHadley, MA 01035413/253 8200http://northeast.fws.gov

Federal Relay Servicefor the deaf and hard-of-hearing1 800/877 8339

U.S. Fish and Wildlife Servicehttp://www.fws.gov1 800/344 WILDSeptember 2013

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