Sounds like over crowding. My 5 adults seem to be seperating into two pairs and a loner that has become a overseer of my dozen young guineas. I have an agressive pair, a royal and a coral, a docile pair, a royal and a coral, and then the lonely coral trying to get the pearls to like herThe only time I've had probelms with cannabalism it's been a space issue. Were the blues younger or smaller than the rest? I would bring in the other blue and put him with the badly injured one that way they can continue to bond.
They were all the same size and had been raised together since I got them a few days after they hatched. It was definitely overcrowding. I actually did bring the other blue in and put it with the badly injured one. I checked him over today. Nothing looks broken. Just a badly chewed on leg. I cleaned it with betadine, slathered neosporin on it, and wrapped it with gauze and vetwrap. Had eleven out there, but just checked on them tonight, and I'm down to ten. A dang ol' snake tried to swallow one of them. It was too big for him, but he snapped its neck anyway. Normally I let snakes go. It wasn't a normal night. :/