I wish I had a pic of the other to show you, but they're too fast and anytime I get near them with the camera I'm lucky to get even one shot, I was lucky to get 2 today. The other is as thin as a twig, os it's not like they're both fat and well fed. I wondered if it was food (if it was mroe aggressive about getting it) but it wasn't like that for all the time we've had it, I just noticed. It isn't cancer, it didn't look like a growth or anything. Not a sickness, either, the other wasn't affected by it. I'll ask my dad about it, he'd know better than me.