Only the mainland population experiences a long-distance migration.
Adults are prone to long-distance migration.
It also conducts long-distance seasonal migrations, generally shifting between shallower and deeper water.
"In this area, with its special difficulties, birds seem to be able to use the sun in long-distance migration," Dr. Alerstam said.
As a result of the improvements in transportation after the Industrial Revolution, long-distance migrations increased in the 19th century.
It is largely resident, apart from dispersion in the wet season, but Chinese birds make long-distance migrations to winter further south.
The long-distance migration of leatherbacks, from the tropics to the high latitudes, is also bound up with their special adaptations.
Of course, in the Southern Hemisphere the directions are reversed, but there is less land area in the far South to support long-distance migration.
Monarch butterflies perform one of the world's most spectacular, annual, long-distance migrations.
In this, it closely resembles the Whinchat, which like S. maurus is adapted to long-distance migrations.