Crows at the North Alabama course we often played had grown accustomed to raiding food from golf carts that pick up snacks at the turn. When the golfers would step over to the tees or the greens, the crows would swoop in and lift a snack, packaging and all! One of my golfing buddies had a smart boxer dog he would bring along to the course, that sat dutifully in the cart throughout an entire round, except when led to the trees to potty. The crows made quick work of the 'guard dog' though ... one brave crow would swoop down at the dog from the side of the cart and draw the animal away from the cart while the others would clean out the snacks!
If 3 walk into the field and 2 walk out, supposedly the crows can't count that high (they get "1" and "many").
If this seems far fetched, the concept of zero was reportedly missing from many "advanced" cultures.