I have 4 RIRs that were born at the end of April, 2015. One of them is a boy. He's started crowing quite loudly and we had to put a no-crow collar on him to keep him for as long as possible. Question is: how much will he grow between now and, say, the end of the year? Sure don't want to strangle him as the collar fits nicely now but will get tight if he grows fast. Would love to have any advice!