Rule 1, it must be edible or able to produce edible stuff to be worth keeping.
My version of this is 'no freeloaders'. Cats must catch vermin; dogs work sheep, catch rats, rabbits, chase foxes and / or guard; pigs must breed or be meat; sheep ditto (unless stupendous fleece for handspinning, I guess), etc. The ponies do not yet comply with this rule, through no fault of their own - so that's my justification for prioritising their training this year!

We do, however, allow flowers which simply feed the spirit.

And I suspect the pigeon pies will be a lucky side benefit of some other things which feed parts other than the alimentary tract..
