I've found this bug a few times. There are pigs (not wildbores), Bunnymen, and bees all in groups, right next to each other! This has happened on land and ocean. Please fix this bug. I have looked at the bug tracker and nobody else reported this. I was using a mod, but i don't think that's the case. It is not a rare bug, because it has happened like three times, but it is not common. I don't know if it happens multiple times on one world. I found this first around December 2015. Keep up the good work!!
Steps to Reproduce
You just have to look around some worlds for it.
This issue has not been confirmed by a developer yet.