Around 4:30 pm Saturday 8/07 at Jug Bay, we saw a peregrine falcon standing on the nesting platform at the end of railroad bed trail , a little to the south on the same side.  We saw a pair of Osprey and a bluebird from the viewing blind area.
 
After looking at pictures of numerous avocet, cormorant and other large black /white water birds, none fit what I saw on 8/6 near River Terrace Park given that this possible frigatebird was as large as a great blue heron at 3-4 feet in length with long legs.
 
Dorothy Paugh
Bowie, MD