Migration Info The first arrival of the Swainson's Thrush in the United States is easy to miss, because it doesn't sing during migration and remains relatively silent (uttering only its brief call notes) for as long as two weeks after reaching its breeding areas. Only after nest initiation, will one begin to hear the haunting flutelike melody. During spring migration, Swainson's Thrushes prefer to remain hidden in dense vegetation; one must learn to identify their unique call note to track their movements and arrival. Western populations tend to migrate up the Pacific coast before moving inland to breeding areas in the Northwest and upper Rockies. Birds from central and eastern Canada pass through the eastern and central states on a broad front. The passage of this species is relatively rapid, because the birds seldom lay over for an extra day en route; one day's feeding appears to be sufficient to fuel a night of migration. As a result, Swainson's Thrushes require specific well-distributed stopover sites with appropriate food sources. Habitat destruction in the southern states has probably had a profound effect on the migratory patterns of this species.