Possible Clues:

• Father's little bird is too old for it now
• Daddy's 20 across is too old for the job
• No longer in one's prime
• Unable to function any more, perhaps due to age
• No longer able, too old or decrepit
• Informally too old to function
• That little bird of Father's is really too old
• The thing about father's little bird is that she is too old
• Too old for anything
• No longer capable of baking pittas