During the breeding season the eagles will establish a territory, typically one to two square miles, and defend it from other eagles that dare to trespass.
During the winter months however, many eagles migrate to places where there is open water. They congregate at these spots because the open water provides them access to fish, one of their primary food sources. It is possible to find eagles not near open water during the winter as long as there is enough food for them to survive, typically this would consist of road kill deer.
While they are all grouped together, during the winter, they are much more tolerant of each other, although there seems to be very little cooperation between the individual birds. Once in a while though an altercation does take place.
Most displays like this one are actually part of the bald eagles courtship ritual. Bald eagles who are courting will often fly up very high where they will lock talons fall spinning towards the earth. Just before they hit the ground they will release and soar back up into the sky. This behavior is called cartwheeling. Coarting pairs will also sometimes chase each other, rolling and flying upside down, through the air.
It is doubtful that this pair, that I photographed in Redwing, MN back in February of last year, was courting. Eagles typically do not begin courting until they reach maturity, at around five years of age. You can tell that these birds are still pretty far from being mature because they have not yet begun to get the white head and tail that are pretty much the indication of a mature eagle. Plus since these birds appear to be about the same size that would indicate that most likely they are probably both the same sex, as with most of the raptor world females are typically bigger then males. It is most likely this was some minor aerial combat over some reason that we will never know.