The Vince Bauldry bird trap uses a 4 x 2 inch piece of 1" x 1/2" 14 gauge welded mesh which is held in an open or "set" position by the top edge of the wire loop when the loop is made to engage one of the protruding cross rods of the welded mesh. The twisted "tail" made when forming the wire loop engages the inside front panel of the box just below the entrance hole.

(from Wisconsin Bluebird, March 1989)