Resident to medium-distance migrant. Green Herons migrate north in late winter and early spring, usually at night and in large flocks. They head back south in late August through October. Eastern breeders migrate via Florida, the Gulf Coast, and the Caribbean, while western breeders head through Mexico. Those breeding in the interior of North America may take either an eastern or a western route. Florida and other southern states also appear to have resident populations. Green Herons tend to wander regionally right after breeding and before migrating, probably in pursuit of food.