Red knots are medium-sized shorebirds that breed in the Arctic and migrate long distances to wintering grounds across the Americas, Europe, Africa, and Australasia. Understanding where red knots live throughout their annual cycle provides important insights into their ecology and conservation.
Breeding Range
Red knots breed in the high Arctic tundra during the summer months of June and July. Their breeding range extends from northern Canada across Greenland, Svalbard, and northern Russia.
In North America, key breeding areas for red knots include:
- Northern Canadian territories like Nunavut, Northwest Territories, and Yukon
- Coastal regions of Hudson Bay
- Arctic islands like Ellesmere Island and Banks Island
Nesting typically occurs near lakes or ponds in flat, treeless tundra. The birds nest right on the ground in shallow depressions lined with grasses, moss, and lichens. Ideal breeding habitat has good visibility, access to fresh water, and an abundance of insects to feed on during the short Arctic summer.
Wintering Range
During the non-breeding season from August to April, red knots undertake some of the longest distance migrations known in the animal kingdom. Different populations winter in coastal and inland habitats across 4 continents:
- Northeastern South America – Northern coasts of Brazil, French Guiana, Suriname
- Southeast United States – Florida, Georgia, South Carolina, Texas
- Northwest Europe – UK, Netherlands, France, Germany
- West Africa – Mauritania to Namibia
- Southern Africa – South Africa and Mozambique
- Middle East – Saudi Arabia, Bahrain, Qatar, Iran, Iraq
- South Asia – India, Sri Lanka, Bangladesh
- Southeast Asia and Australasia – Thailand, China, Korea, Japan, Northwest Australia
Wintering red knots utilize a variety of coastal wetland habitats including estuaries, mudflats, sandy beaches, salt marshes, and mangrove swamps. Inland lakes, rivers, and agricultural fields are also important. Good foraging areas provide abundant small mollusks, crustaceans, marine worms, and other invertebrate prey.
Migration Stopover Sites
Red knots depend on key staging and stopover sites to rest and feed during their migratory journeys up to 18,000 miles long. Some vital migration hotspots include:
Delaware Bay, New Jersey and Delaware
Delaware Bay serves as the most important spring migration stopover site for red knots in the Western Hemisphere. Each May, the birds stop to feast on nutrient-rich horseshoe crab eggs to refuel for their arduous journey to the Arctic breeding grounds. Annual surveys indicate around half the entire red knot population concentrates here during peak migration.
Yellow Sea, China and Korea
The Yellow Sea provides indispensable fueling grounds for red knots migrating north from Australia and New Zealand in the East Asian-Australasian Flyway. Dramatic habitat loss due to land reclamation has diminished food supplies, resulting in population declines.
Banc d’Arguin, Mauritania
Banc d’Arguin National Park provides critical wintering area for the Afro-Siberian red knot population that migrates from Arctic breeding areas to coastal West Africa. The park provides shelter and abundant food on mudflats, sandflats, and beaches.
Northwest Australia
Extensive mudflats along the coasts of north and northwest Australia contain some of the largest concentrations of red knots outside of the breeding grounds. Roebuck Bay near Broome sees especially high numbers during migrations between New Zealand and Siberia.
Population Status and Threats
Many red knot populations have experienced sharp declines due to threats on their breeding grounds and migration routes. The RV-rufa population that migrates from Tierra del Fuego to the Canadian Arctic crashed by around 75% since the 1980s. Conservation groups petitioned for it to be listed as an endangered species but this has not yet happened.
Major threats to red knots include:
- Habitat destruction – especially of key migration stopover feeding grounds
- Overharvest of horseshoe crabs, an essential food source, particularly in Delaware Bay
- Disturbance from human recreation activities
- Oil spills and pollution
- Climate change effects on tundra breeding habitat
Protecting crucial coastal wetland habitats and limiting horseshoe crab harvests are vital steps needed to stabilize remaining populations. Public education, regulations on shoreline development, responsible ecotourism, and restricting access to sensitive sites during migration can also help safeguard red knots into the future.
Conclusion
Red knots are highly migratory shorebirds that breed in the high Arctic and utilize coastal habitats across hemispheres during the non-breeding season. Key sites for conserving the species include breeding grounds in northern Canada, Russia, and Greenland as well as critical migration stopovers like Delaware Bay, the Yellow Sea, Banc d’Arguin, and northwest Australia. Habitat loss on wintering areas and migration routes driven by human disturbance and development poses the biggest threat to red knot survival.
