So far I have four runner ducklings. One of them came out crested, and he's the one I'm worried about. He's extremely listless and doesn't care if the other three move away from him, he just sleeps and doesn't move. He can walk because I put them all on the floor to check them out and he would follow my hand all over the place. Also, his eyes seem about half the size of the other ducklings. Do you think something could be wrong?