The shorebird with a rufa subspecies that migrates between the Arctic and Tierra del Fuego is the red knot. Its scientific name is Calidris canutus, and the long-distance migrant belongs to the sandpiper family.
The rufa subspecies, Calidris canutus rufa, breeds in the Canadian low Arctic and winters along the Atlantic coast of South America. Some individuals travel more than 9,000 miles between the Arctic and the southern tip of the continent, then repeat the journey northward. The route includes critical coastal stopovers where birds refuel.
Red knots change diets with the seasons. On Arctic breeding grounds they eat insects and other arthropods, while at coastal staging and wintering sites they consume hard-shelled molluscs and other invertebrates. Delaware Bay is especially important to many migrating rufa knots because horseshoe crab eggs provide a concentrated spring food source.
The species is divided into six recognised subspecies with different breeding and wintering routes. That diversity can cause confusion: not every red knot follows the Arctic–Tierra del Fuego route, but the rufa population is the famous intercontinental traveller described in the question.