Most of our robins spend the entire year in the same general area. There is some migration, but usually not far. And robins that might move a little south from here might well be replaced by robins who arrive here from more northern areas to spend the winter. When the weather starts getting cold, In the spring and summer, when we see robins on our lawns, worms and larger crawling insects are a large part of the robins' diet. However, when the earthy creatures that are the robins' summertime fare begin to disappear, the robins change their dining habits.
Robins are omnivores.
Even in summer they love fresh fruits and berries. So when the worms dive deep, the robins fly up to the shrubs and trees and dine on berries. Thus, during the cold months, robins live in and about the open woods, and especially in wetlands and swamps, where they are most apt to find the kinds of hard, wild berries that last through the cold season. The robins do this in sizable flocks and spend the nights in roosts of many birds. This social behavior is unlike the way we're used to seeing robins.