An old pinto, eh?  Anything can cut through that tin can.  A bird talon dagger?  A dime a dozen at your local D&D Fantasy Game Shop.  If it happened in a parking lot, the bird feathers could be decorating someone's front grill.  Burn marks on the asphalt?  Take to higher ground and see if there is a pattern connecting them.  I suspect witchcraft and a sacrificial rite at the very least.