Possible Clues:

• National bird of the US, now common only in Alaska
• Great Seal image
• Flier showing lad badly bitten by dog
• National symbol
• Sacagawea flip side
• Bird a lord fed to dog
• Common name for the national emblem of USA
• Bird on the presidential seal
• Bird on the Great Seal of the United States
• US flier sailed regularly aboard Darwin's ship