Purcell suggests a few tricks for spotting the younger birds among the masses. Pigeons have grayish-brown eyes for the first six months of their life, after which they turn orange or red. And the bit of flesh above a pigeon's beak, the cere, is gray when the bird is younger, instead of white. You can also identify juveniles by their behavior, Purcell says—although it's hard to tell which birds are acting immature when all of them are pooping on statues.