The pilot reported that the purpose of the flight was to maneuver at low altitude and chase birds away from designated fields. The pilot further reported that he had previously completed about 8 to 10 turns over the target field and during a steep "reversal turn" to the left the airplane impacted terrain. The pilot had no other recollection of the accident. According to a private pilot witness located about 700 feet from the accident airplane, he observed the accident airplane enter a "steep turn" to the left about 50 to 75 feet above the ground. The witness further reported that the airplane "stalled and spun into the ground", and that the engine noise became louder seconds before impact. The fuselage and both wings were substantially damaged. The Federal Aviation Administration Pilot's Handbook of Aeronautical Knowledge in part states: an airplane will "stall at a higher indicated airspeed when excessive maneuvering loads are imposed by steep turns, pull-ups, or other abrupt changes in its flight path." Stalls entered from such flight situations are called "accelerated maneuver stalls," a term, which has no reference to the airspeeds involved. Stalls which result from abrupt maneuvers tend to be more rapid, or severe, than the unaccelerated stalls, and because they occur at higher-than-normal airspeeds, and/or may occur at lower than anticipated pitch attitudes, they may be unexpected by an inexperienced pilot. Failure to take immediate steps toward recovery when an accelerated stall occurs may result in a complete loss of flight control, notably, power-on spins. The pilot did not report any mechanical malfunctions or failures with the airplane that would have precluded normal operation.