Ospreys are such a common sight above Chesapeake Bay during the summer months that it’s easy to forget that our “local” birds spend almost half their year in and around the coastal and inland waters of South America. Indeed, ospreys are one of the most wide-ranging birds in the world, with populations on all continents except Antarctica, and on many oceanic islands. The one constant of their distribution is proximity to water.
Ospreys are common warm-weather residents of Chesapeake Bay and other East Coast estuaries as far north as the Canadian Maritime provinces. Local birds arrive in Chesapeake Bay in early March and remain into October, when they begin to migrate south for the winter. Most spend the colder months in South America, ranging from Venezuela to as far south as Paraguay and even Argentina.
During their fall migration, East Coast ospreys move southward in a broad band that stretches from the coast several hundred miles inland. This flyway narrows to the tip of Florida, then continues to Cuba and Hispaniola. Some osprey remain in the Caribbean, but most make a beeline across 500 miles of open water to Venezuela before fanning out further south into the Amazon Basin and the Pantanal, the world's largest freshwater wetland.
Young-of-the-year osprey (those hatched and fledged during the current summer) typically begin their southward migration several weeks later than older juveniles and adults, presumably to further hone their recently learned fishing skills and increase their energy stores. Remarkably, instinct alone then guides them all the way to South America, a journey of from 2,500 (Venezuela) to 5,000 miles (the Pantanal). These young-of-the-year birds then typically spend an entire year and a half in South America before making their return migration.
Ospreys conserve energy during their lengthy spring and fall migrations by alternately using rising air currents (thermals) to soar to great heights, then gliding forward and downward before catching the next thermal. Tagging studies show that they can travel up to 500 miles in a single day, although they typically average around 100 miles.