Possible Clues:

• Might its song make the little one sick?
• Be in a hurry at last to get a bird sickness
• Mouth fungus or songbird
• The sort of complaint that Mavis might have
• Singing bird or mouth-troat infection
• 'Song' bird
• Incomplete article on career gets the bird
• American's finished off quiet songbird
• No end to the haste to locate songbird
• Common songbird or throat infection