American Robins live year round in my area. A pair or two will overwinter with the greater number migrating back into the watershed in early spring. Large flocks gather, at the beginning of each year, throughout the top of one of the taller trees in the canopy above the creek as if to assess their number. They descend en masse to forage in the lawn or empty the birdbath with their overcrowded and vigorous splashing. They soon disperse with several pair remaining in the neighborhood throughout the summer.