Abstract: A one way door animal excluder includes an elongated enclosure to support a door within. The door pivots between an open and a closed position wherein an animal can push the door open from only one side. A top plate is fitted atop the enclosure and crimped at flanges of the top plate, with at least one flange also crimped around a hinge wire of the door to form a pivotal attachment of the door to the enclosure. The top plate includes an opening with tabs extending therein to form a spring mandrel to support a torsion spring. The torsion spring biases the door to close. The spring includes a loosely wound coil that may be temporarily compressed to install upon the tabs. An upward extending hump of the top plate is positioned adjacent to the spring coil to protect the spring coil structure.