Related Clues:

• Extinct flock
• They travel in formation
• Wiped-out avians
• Silly ones
• Saps
• Birdbrains
• They fly in skeins
• Dumbbells
• Chowderheads
• Skein members
• Long-gone birds
• Down source
• Boneheads
• Dim bulbs, so to speak
• Parts of a V formation