The Swallow-Tailed Kite, a bird of prey!
It sure is a big bird with a wing span of 4 ft (120 cm), they eat large insects, small reptiles (such as lizards and snakes) , small birds and eggs, and build their nests in the tallest trees they can find.
The beautiful birds are summer visitors in the southeast United States and migrate to South America for the winter months (where those birds live year round).
Even though it seems to be a rare bird, it is not on the endangered or threatened list. But you can report a sighting on this webpage (the Avian Conservation Center)