I learned the hard way, it was really funny! Purchased one white and one blue silkie (supposedly pullets). The white one grew the fluffy cotton ball head but the blue one did not. Duh, I didn't even get a clue when it started growing a comb with tufts of blue feathers coming out behind the comb. I thought, being a novice with chickens, that it was just a genetic thing! I also noticed the tail feathers displayed themselves differently. Then one day, I thought I heard a "cat" in the enclosure.............well, you can imagine my surprise when I saw HIM flapping his little blue wings and squeaking out his first crows! Now, with everything explained, he really is quite attractive and being the only "Roo" among 9 large ladies and the one little white silkie, he really takes his position seriously and struts around taking care of everyone! It is hilarious!