The Migration of Storks

White storks are considered a sign of prosperity.

While several species of stork are found on every continent except Antarctica, the black stork and white stork have the most studied and dramatic migrations. The white stork is a special favorite in Europe, where their presence nesting near chimneys in springtime gave rise to the popular myth that they deliver babies. They are still considered a sign of prosperity to many, and their beauty, size and large flocks make migration a stunning sight.

Black Storks

The black stork, an endangered species, migrates in small groups. Unlike some types of storks, which breed in colonies, the black stork prefers nesting solo. It breeds over an extensive range, including central and eastern Europe, parts of southern Africa, and south and southeast Asia. Black storks winter in the Iberian Peninsula, Africa, the Middle East, and parts of Asia.

White Stork Migration Routes

European white storks fall into one of two groups: an eastern population and a western. The eastern population includes storks dwelling in eastern Europe and the Middle East. The western population lives in western Europe and northern Africa. The two groups each have their own migration route. The western birds migrate southwest through Gibraltar and winter in west Africa. The eastern birds transit through the Middle East to winter in east Africa. Sometimes birds from the two populations meet up in Chad and Niger.

Migration Studies

The study of white stork migration routes began early in the 20th century with the ringing of nestlings. Rings were attached in the breeding areas, and information was collected through subsequent recoveries of the birds. Researchers marked 31,626 storks between 1964 and 1993. During these years, they reconnected with these birds 6,107 times. More recently, the Max Planck Society, a bird research society in Germany, began using satellite telemetry to track storks.

White Stork Migration Pattern

Flocks of storks take advantage of a group dynamic in riding the winds.

On a long migration, storks must conserve their energy. Keeping their wings rigid while soaring in thermal winds saves a lot of flapping. Depending on the wind conditions, they may find it more economical to choose a higher altitude. Forming larger flocks also improves their glide ratio, compared to flying individually. But the flocks are not very organized, and the birds do not seem to pair bond outside of the breeding season.

Nesting

Of course, breeding and nesting are integral parts of the migration. Storks can be divided into two nesting personalities: colony nesters and solitary nesters. A nesting colony can be anywhere from a few breeding pairs up to several thousand. In Africa, several types of storks, such as yellow-billed, marabou and Abdim's storks, may all nest together. Herons, egrets and pelicans might join them as well. Solitary nesters like Jabirus and Storm's storks seem to form more enduring pair bonds, and may return to the same nest over and over. Most storks nest in trees, but some build in cliffside hollows or on the ground.

References

• Convention on Migratory Species: Adebar Reveals His Secrets
• BFN : Eastern European White Stork Populations
• Arkive: Black Stork
• San Diego Zoo: Birds--Stork