Pelican.
One possible three-letter word for "bill" would be "IOU." Another might be "neb," which is a bird's bill.
ROCS
Avocet
Avocet
Goose Egret
try storks. it has the smae sound ending 5 letter bird with plural.
Ibis?
The "bill" is the bird's beak, or mouth.
albatross.
A six letter word for a bird of prey starting with the letter R is "raptor."
word
a bird's mouth is his beak