Why don't you grab a flashlight stick your head down in there and see what it is?
You'll gain man points for your bravery. Rabies shots aren't nearly as bad as they used to be. They cost a couple of thousand dollars or more depending on your insurance and you don't have to get them in the stomach any more.
You'll need to figure out how it got in there and properly fix the hole to keep it and its cousins from coming back.
Last winter I had a bat in my attack and a raccoon trying to tear the siding off of my house at 4:30 every morning. Mammals are a pain the ass. Be happy that it isn't a human.