Not exactly funny, but I remember one barn that had several overfed cats who had no interest in mousing…and I’d often go into the warm tack room to find ENORMOUS rodents sitting and eating the cat foot laid out in dishes. Completely unaware of the irony.
I’m a complete PIA, so I take my treats to the barn and back home with me every time. Unfortunately, it sounds like your barn mate is the type of person who passively aggressively digs in and refuses to clean as a point of principle. I’m not sure the tin will really help.
It’s weird, sometimes, the different attitudes people have about the appropriate way to keep food…I’ve been at barns in which people keep their tack in immaculate condition, but they’ll leave obviously slimy, rotting carrots and apples still in the plastic bag in their lockers or trunks and never throw them out.
I agree that the barn owner/manager has to address the issue. Even though what you’re requesting is 100% reasonable (that all treats must be in secure rodent-proof containers), just like with any common area etiquette–like keeping the wash stall clean or picking the arena after they use it–unless it’s official policy, there are some people who won’t do it otherwise, even though it’s basic courtesy. I also agree that while an uncovered treat buffet is definitely not helping the mouse problem, it’s likely not the sole source, and the management will probably need to take other steps.