My school pal shot a grouse in the UK illegally on an estates land with a .410 no less back in 1967 when he was 17. He took it home and his mother who had no idea what to do, got a cookbook from the library and it said to first hang it for five days before cooking in the oven. That she did but the book never mentioned dressing the bird out first.
They could not go into the kitchen for two days afterwards as the stink was so strong, it always makes me laugh to think back.