Ginormous hitboxes seems to be Frontier's specialty, at least in regards to this particular game. It's (unfortunately) clear that the adult animals do not need to have such large hitboxes, both because the juveniles don't, and because a mod adjusts that by script, not by wrestling with the engine. I think many of the static items don't either - though in this case, it may be triggering the platform animations so I don't know what 'size' they need to sort that out.