Sooty-headed Shovelers:
Olive-backed Phoebe:
American Crow and Ring-billed Gull sized equal:
Finally pics of a Sharp-shinned Hawk: (adult) 
squared-off tail; little head projection; eye centered on head: 

Earlier reported 5 Surf Scoters: One is subtly different.
Female can show paler wing coverts:

HY Forster's Tern is easy to distinguish from adult Frosty (Forster's) Tern:

Bill Rudden
St. Louis
The Audubon Society of Missouri's Wild Bird Discussion Forum
ASM Fall Meeting: September 25-27 at Lake of the Ozarks State Park