The calves are born during the spring migration from April to June.

The birds pair off after arriving at their nesting areas, or possibly even before spring migration.

"As many as a hundred species in a day may be sighted during spring migration."

But peak spring migration starts at the end of April.

During spring migration, each transect will be surveyed five times.

I had first seen it on out Skerries during spring migration.

During the spring migration (March), waterfowl are at their peak abundance.

Health officials had expected wild birds to carry the disease into Europe from Africa in the spring migration.

They generally migrate during the night, but may travel during the day in the spring migration.

Large numbers of migrating songbirds stop in the area to rest during their spring migration.