This happened about 15 years ago... give or take.
I kept my drums in the 'shop', which is often left open and happens to be surrounded by a few million acres of wilderness, where I live. Anyway, I hadn't played in a few months when i got a call to do a 'fill in' that evening at a resort on a lake. After arriving, I unloaded the drums and set the cases up on stage. The bass drum case was resting on it's flat bottom, and when opening it I suddenly noticed a strange odor emanating from somewhere within the cases darkened confines.
Without a warning, out from the case sprang about a dozen small mice, scampering about the stage and dance floor while those present jumped as if Olympians up onto their chairs and tables to escape the wrath of the paniking beasts. LOL, That was embarrassing!!
Because the bd had no resonator, I took the drum outside and dumped out I'd say about a shovel load of smelly ol' mice droppings, and then with damp rag in hand, wiped the shell 'clean' while guests and band members pointed my way laughing at you know who's expense. The mice? Well, this happened right at the stages open back door and most of em' fleed into the 'yard', where a family of cats that lived under the outdoor deck responded with glee to the unexpected frolic and feast. It was a real scene for those that saw it. True story!!!