Possible Clues:

• Sounds as if only one such bird is able bo be a brace of them
• This makes it sound as if a brace of birds can yet be only one bird
• One with huge bill wrecking account - hundred short?
• Sounds as it the pair of them is able to get a big bill
• Froot Loops spokesbird
• Sounds as if a couple is able to make it for Big Bill
• Oh, you can't get in there with such a big bill!
• The sort of brace that might be able to give one a big bill, by the sound of it
• Is a couple able to make one for Big Bill?
• Bird a small number are able to identify by sound