The air carrier flight was substantially damaged when it impacted geese while being vectored for approach. Night visual meteorological conditions prevailed. The pilots heard a “thump.” They reportedly watched the engine indications and saw nothing unusual. They visually inspected their respective wings and saw no damage. The airplane landed without incident at its destination. Inspection of the airplane revealed damage to the following areas: the vertical stabilizer front lower spare, the vertical stabilizer to the rear lower spare, the dorsal fin right hand skin panels and support structure, flange damage to rudder lower support rib for leading edge panel, and the left hand wing front spare. Probable Cause: The in-flight collision with geese during approach. The contributing factor was the bright night conditions