Possible Clues:

• Old fogeys
• Extinct Mauritius birds
• Some old birds in a couple of parties begin to swoon
• Boneheads
• Two parties with schemes to start with -- but they were never going to fly!
• Manage to sleep soundly? They never got up
• So odd but sadly they're no more
• Utter fools
• Noodleheads
• Rattlebrains