the following mods are currently active.
more pets, more leather, adv mode reactions, silk eggs, mythical beast, the wild hunt, plump helmets, bogeymen, -mancers, artic additions creatures, artic additions plants, prefstrings, engravings, all of stal'a armory pack, all of the historic arms and armors.
the active civs
are dwarves, elves, humans, orcs, succubi and kobolds
the error log had this to say.
*** Error(s) found in the file "raw/objects/creature_random_myth_beast_standard_mdf.txt"
SEAL_ANIMAL_WEEVIL BP Add Type GELDABLE Was Not Used
I somehow doubt its responsible but what do I know?