Most immature Bald Eagles migrate, but if adults have nested in an area where water remains open year-round, they are more likely to remain in or near their breeding territories all year, defending their nest site. The risks that migrating pose are not worth it if they can get all the food they need (1/2 – 1 ½ pounds/day) to survive the winter, which they can in much of the Northeast. In the past few decades, the number of overwintering eagles has been increasing in New England to the point where it is not unusual to see adult eagles near and even at their nests any month of the year. (The accompanying photo taken in Vermont on 11-14-20.)
Eagles do make changes in order to adapt to winter conditions. While they continue to feed on fish, they also do a fair amount of scavenging in the winter, feeding on roadkills and animals such as deer that may have wandered onto the ice, fallen and not been able to get back up.
Another behavioral change that occurs is the tendency to gather in large numbers, clustering close together on branches at overnight roost sites. Often stands of white pine provide the birds with some protection from the cold wind, thus allowing them to conserve energy. An additional advantage of this communal life style is that they get cues from each other as to where sources of food may be by watching the direction in which the first birds take flight in the morning (those with a known source of food often are the first to leave the roost).
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