I probably knew some time ago, but I have honestly always looked at the Bald Eagle as the National Bird, not just a symbol of America. I have been somewhat consumed by the Esdras Eagle prophecy and, I believe America is the three-headed eagle that he saw, which is also the fourth beast Daniel saw.
It is a bit of an irony because so many people have believed the prophecy was referring to Rome. But I have never heard of the eagle or bald eagle being associated with Rome. If you consider the feathers matching the presidents and now the eagle officially representing America, it is harder and harder not to align the prophecy with the United States of America.
In due time, we will have a more certain understanding.