Ok, Short Eared Owl maybe. I hate to take a big shit on your quest here, but there is the question of who the sign was meant for, if it is a sign. It seems to be in a pretty public place. Maybe it was never meant for you, but someone else instead.

Dead animals don't bode well anyway so be happy if it isn't for you. True story, when I was kid my 14 year old brother found a cow skull. He decided it would a neat prank to place it on the neighbor's front porch. What we didn't know at the time was that our neighbors were the one of biggest Italian mafia families in the province. My parents never told us, they thought it was best if we never knew. My brother "hung himself" two days later. That's what you get for pulling a stunt like that with the mob.

The whole cow skull thing never even meant anything to me at the time it happened. It wasn't until years later that I put it all together. I still haven't told my parents about the cow skull.