A number of large marine fishes, such as the tuna, migrate north and south annually, following temperature variations in the ocean.

The economic advantages of migrant labour have come at a social cost: while some workers migrate annually, other families are divided often for many years.

Seven of nine known species of great whales annually migrate to the Antarctic to feed.

Thence it had been their custom, time out of mind, to migrate annually to some portion of the earth.

Their flight is not powerful, but can continue for long periods, and many species migrate annually.

They may emigrate as a result of food shortages or environmental conditions, but they do not migrate annually.

The flight of those Rallidae able to fly, while not powerful, can be sustained for long periods of time, and many species migrate annually.

In some climates court migrated annually between a summer and a winter capital.

Once, 16 million salmon migrated annually to the Columbia River system.

According to the latest statistics, some 60,000 of them migrate through the area annually.