The rufa red knot is truly a master of long-distance aviation. On wingspans of 20 inches, some knots fly more than 9,300 miles from south to north every spring and repeat the trip in reverse every autumn, making this bird one of the longest-distance migrants in the animal kingdom. Surveys of wintering knots along the coasts of southern Chile and Argentina and during spring migration in Delaware Bay on the U.S. coast indicate that a serious population decline occurred in the 2000s.
The knot’s unique and impressive life history depends on suitable habitat, food and weather conditions at far-flung sites across the Western Hemisphere, from the extreme south of Tierra del Fuego to the far north of the central Canadian Arctic. Knots need to encounter these favorable habitat, food and weather conditions within narrow seasonal windows as the birds hopscotch along migration stopovers between wintering and breeding areas. For example, the knot population decline that occurred in the 2000s was caused primarily by reduced food availability from increased harvests of horseshoe crabs, exacerbated by small changes in the timing that knots arrived at the Delaware Bay. Horseshoe crab harvests are now managed with explicit goals to stabilize and recover knot populations.
Knots may be particularly vulnerable to climate change, which is likely to affect:
- the arctic tundra ecosystem where the knots breed;
- coastal habitats due to rising sea levels;
- food resources throughout the bird’s range; and
- storm and weather patterns.
Knot numbers appear to have stabilized in the past few years, but they remain at low levels relative to earlier decades. Biologists from the U.S. Fish and Wildlife Service, state natural resource agencies, and non-profit organizations all share a concern for this race of red knot and are pooling efforts to identify what needs to be done to prevent further losses. Together with these partners, the U.S. Fish and Wildlife Service is dedicated to working to cons/erve this extraordinary bird.
UPDATE, SEPT. 27, 2013: Rufa red knot proposed for "threatened" status under Endangered Species Act
News release (PDF)
Questions and answers
Resources: Maps, migration infographic, multimedia timeline, video and photos
Red knot information
Bandedbirds.org, for shorebirds with colored bands/lettered flags
Ebird.org, for bird sightings
See Ebird map for all red knot subspecies