Possible Clues:

• Letter carriers in 'Harry Potter'
• Headless chickens -- 22 engaged in 18,4?
• They hoot at night
• Nocturnal birds with big eyes
• Ron's Pigwidgeon and Harry's Hedwig, e.g
• Members of parliaments
• 'Wise' sorts
• Birds with a 'snowy' variety
• You can't say they won't give a hoot!
• 'Legend of the Guardians' birds