Long Distance Migration

—Mary Gillick, Program Director

Red knot, Calidris canutus rufa. Photo: audubon.org

All school-children learn that birds fly south in autumn and return in spring. It sounds mysterious to earthbound creatures. How do they find their way? How far and how fast do they travel?

Scientists have developed a way to tag many species with identification bracelets to learn the extent of their migration patterns. The project depends on bird watchers around the world to report their sightings and aid in gathering information.

One species of shorebird called the red knot or Calidris canutus rufa has been well researched since the mid-1990s. The yearly roundtrip migration route encompasses 18,000 miles.

In early September, the birds leave their nesting homes around Hudson Bay, Canada and travel to the east coast of Quebec. Within a week or so, they brave their first long leg of their southward journey travelling at 40 miles per hour for four days to the mouth of the Amazon River in Brazil.

They fly non-stop over the Atlantic Ocean for over 3,500 miles to land on the shore and refuel on clams and mussels. They spend a couple of weeks more resting before heading to the coast of Argentina in Patagonia another 3,700 miles farther!

The red knots eat young soft mussels called spat from October through February before their inner clock tells them it is time to head back north for the breeding season. They head to southern Brazil in April and prepare for the long flight back to make it in time for a special spring event on the eastern coast of Delaware.

This can be the longest leg in their roundtrip circuit as they fly close to 5,000 miles in six days! When they land they refuel in the Chesapeake region on tiny green eggs that were deposited on the beach during the May high tides by the ancient looking horseshoe crabs.

LEARN MORE ABOUT RED KNOTS

To learn about the flight of a particular red knot, numbered B95, check out Moonbird by Phillip Hoose.

Visit the Audubon Society for more information on red knots and read the article in the latest issue of Audubon magazine.