Happens a lot where I live in the Highlands, them or a plassy bag with a Salmon in it.
Just learn to live with it as one of the strange country customs. (ask no questions and you'll be told no lies)
It's a message that you are accepted as being part of the local community.
As somebody else said, it's a different message if you're a game-keeper and you keep finding them Nailed to your front door!