ABSTRACT
Except in the southern and coastal portions of the US, where some are resident, most robin populations are migratory. Winter roosts containing thousands of individuals are common in southern states from December to mid February. Northward-migrating flocks may appear as early as mid February at the latitude of New England, but most show up there in mid to late March. The dates of territory establishment and the onset of reproduction vary with latitude and elevation. Breeding male robins begin broadcasting advertising songs from conspicuous perches at least 2 weeks before initiation of the first clutch. Early morning hours provide the longest and most intense periods of song. Territorial singing continues throughout the breeding season, but the morning and evening periods of full song are reduced as the season progresses. Males actively defend a nesting territory, but both members of a pair may forage at some distance in an undefended area.
